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Active Forums => QB64 Discussion => Topic started by: johnno56 on June 10, 2018, 06:08:54 am

Title: Collision Detection
Post by: johnno56 on June 10, 2018, 06:08:54 am
Simple question that may not have a simple answer.

Some languages have collision detection built in and some do not.

I would like to know what method do users of QB64 prefer to employ for sprite collision detection?

J
Title: Re: Collision Detection
Post by: johnno56 on June 10, 2018, 07:08:02 am
I have whipped up a simple Bounding Box collision test.
I had to use 'help' to try and figure out mouse commands... lol

This would be ideal IF the sprites were either square or rectangular is shape (tiles) but no so much for irregular shaped sprites.

Code: QB64: [Select]
  1. '
  2. '   Collision - Test 1
  3. '
  4. '   Bounding Box
  5. '
  6. SCREEN _NEWIMAGE(640, 480, 32)
  7. _TITLE ("Bounding Box Collision Detection")
  8.  
  9. box1top = 190
  10. box1bottom = 290
  11. box1left = 270
  12. box1right = 370
  13.  
  14. collision = 0
  15.  
  16. DO: k$ = INKEY$
  18.         CLS
  19.         LINE (box1left, box1top)-(box1right, box1bottom), _RGB32(255, 255, 0), B
  20.  
  21.         box2left = _MOUSEX - 50
  22.         box2top = _MOUSEY - 50
  23.         box2right = box2left + 100
  24.         box2bottom = box2top + 100
  25.         LINE (box2left, box2top)-(box2right, box2bottom), _RGB32(255, 128, 0), B
  26.  
  27.         GOSUB collide
  28.  
  29.         IF collision = 1 THEN
  30.             COLOR _RGB32(0, 128, 0)
  31.             _PRINTSTRING (283, 230), "Collision"
  32.         END IF
  33.         _DISPLAY
  34.     LOOP
  35. LOOP UNTIL k$ = CHR$(27)
  36.  
  37. collide:
  38. IF (box1bottom < box2top) OR (box1top > box2bottom) OR (box1left > box2right) OR (box1right < box2left) THEN
  39.     collision = 0
  41.     collision = 1
  44.  

I can patch together a 'circular' system if needs be...

This 'Box' system works ok, but I would appreciate it someone could suggest a better system...

J
Title: Re: Collision Detection
Post by: Petr on June 10, 2018, 07:42:00 am
Hi Johnno56,

For collision detection, I use a method where I write the coordinate of the boundary of an object in the field, and then compare the coordinates, whether or not the penetration has occurred (before plotting). I'll send down the demo here. But first, I'm sending a slightly-repaired sample program from the IDE Help for the CIRCLE command:

Code: QB64: [Select]
  1. 'collision detection    -  mouse in circle
  2.  
  3. SCREEN _NEWIMAGE(800, 600, 256)
  6.     CLS
  7.     IF Circle_Collis(_MOUSEX, _MOUSEY, 60, 400, 300) THEN LOCATE 1, 1: PRINT "   Collision" ELSE LOCATE 1, 1: PRINT "No collision"
  8.     CIRCLE (400, 300), 60
  9.     _DISPLAY
  11.  
  12.  
  13. FUNCTION Circle_Collis (x AS LONG, y AS LONG, r AS LONG, cx AS LONG, cy AS LONG)
  14.     xy& = ((x& - cx&) ^ 2) + ((y& - cy&) ^ 2) 'Pythagorean theorem
  15.     IF r& ^ 2 >= xy& THEN Circle_Collis = 1 ELSE Circle_Collis = 0
  17.  
Title: Re: Collision Detection
Post by: johnno56 on June 10, 2018, 08:23:29 am
Cool. A much smaller version of the 'circle or radius' detection system. Basically checking the distance between the mouse pointer and the radius of the circle. Your listing seems to be more efficient that mine. Cool. Thanks for the assistance. Much appreciated.

J
Title: Re: Collision Detection
Post by: Petr on June 10, 2018, 10:49:57 am
Here is the promised example. Basically, it's all based on the fact that what you see on the screen does not match what you have on memory. For example, the game environment. You make the post on a monochrome background, and then you just watch the penetration of the points on the picture screen in the memory. I think the dinosaur demonstration shows it best:

Code: QB64: [Select]
  1. 'very easy method based on color difference:
  2.  
  3. A& = _NEWIMAGE(100, 50, 256)
  4. _DEST A&: PRINT "Secured"
  5.  
  6. SCREEN _NEWIMAGE(400, 300, 256)
  8.  
  11.     IF white(_MOUSEX, _MOUSEY) THEN LOCATE 1, 30: PRINT "   Collision detected" ELSE LOCATE 1, 30: PRINT "No collision detected"
  12.     LOCATE 13, 1: PRINT "Press ESC for show MEM method"
  14.  
  15.  
  18.     IF MEM_White(_MOUSEX, _MOUSEY, 0) THEN LOCATE 1, 30: PRINT "   Collision detected" ELSE LOCATE 1, 30: PRINT "No collision detected"
  19.     LOCATE 13, 1: PRINT "Press ESC for show virtual screen method"
  21.  
  22.  
  23. 'but in practice objects use more than one color. For show you, hot to create it, use image:
  24. _FREEIMAGE A& ' kill text image from memory
  26. A& = _LOADIMAGE("rex.jpg", 32)
  27. _SETALPHA 0, _RGB32(255, 255, 255) TO _RGB32(200, 200, 200), A& 'set white color as transparent. BUT! Trick is this: IF is used the same resolution for screen as is resolution picture, you need not
  28. REDIM Border(0, 0) AS _BYTE '                                    recalculating coordinates, so you only show to source image (source in memory an on screen are now different)
  30. _PUTIMAGE , _SCREENIMAGE '                                       first draw background image
  31. _PUTIMAGE , A& '                                                 place image with set alpha channel (but A& contains again this colors and you can see to it ALONE using _SOURCE and _DEST)
  32.  
  33.  
  34.  
  37.     IF DetectRex&(_MOUSEX, _MOUSEY, A&) THEN LOCATE 1, 30: PRINT "   Collision detected" ELSE LOCATE 1, 30: PRINT "No collision detected"
  38.     LOCATE 40, 1: PRINT "Press ESC for show VIDEO collision detection"
  40.  
  41.  
  42.  
  43.  
  44. ' last example is video collision detection. Its the same as in rex case, but for more pictures, so as source is on screen area.
  45. LOCATE 1, 30: PRINT STRING$(40, " "): LOCATE 40, 1: PRINT STRING$(50, " ")
  46. Horse& = _LOADIMAGE("horseU.jpg", 32)
  47. TYPE FRAME ' this is coordinates TYPE (struct) for my "videoplayer" it write correct coordinates to array, none images
  48.     Source AS LONG
  49.     X_Start AS INTEGER
  50.     Y_Start AS INTEGER
  51.     X_End AS INTEGER
  52.     Y_End AS INTEGER
  53.     Index AS _UNSIGNED _BYTE
  55.  
  56. REDIM SHARED Horse(0) AS FRAME
  57. VideoLoad Horse(), Horse&, 4, 3, 146, 95, 0, 0
  60.     LINE (10, 10)-(156, 105), _RGB32(0, 0, 0), BF
  61.     VideoPlay Horse(), 10, 10, 1 'video is not zoomed, so is not need recalculating coordinates
  62.     IF DetectHorse&(_MOUSEX, _MOUSEY) THEN LOCATE 1, 30: PRINT "   Mouse on horse" ELSE LOCATE 1, 30: PRINT "No mouse on horse"
  63.     LOCATE 40, 1: PRINT "Press ESC for end."
  64.     _LIMIT 30
  66.  
  67. PRINT "It is all..."
  70. _FREEIMAGE Horse&
  73.  
  74.  
  75.  
  76.  
  77.  
  78.  
  79.  
  80. FUNCTION DetectHorse& (x AS INTEGER, y AS INTEGER)
  81.     x = x + 10: y = y + 10 ' because Videoplay set it to start coordinates 10, 10
  82.     IF x > 10 AND x < 156 AND y > 10 AND y < 105 THEN 'is mouse in video coordinates?
  83.  
  84.         DIM O AS _MEM
  85.         O = _MEMIMAGE(0)
  86.         _MEMGET O, O.OFFSET + IN4&(x, y), value&
  87.         R = _RED32(value&)
  88.         G = _GREEN32(value&)
  89.         B = _BLUE32(value&)
  90.         IF R <= 20 AND G <= 20 AND B <= 20 THEN DetectHorse& = 0 ELSE DetectHorse& = 1 ' > 200 because color > 200 is set as transparent with setalpha and are not visible. Its background rex picture.
  91.         _MEMFREE O
  92.     ELSE DetectHorse& = 0: EXIT FUNCTION
  93.     END IF
  94.  
  96.  
  97.  
  98.  
  99. SUB VideoPlay (array() AS FRAME, X AS INTEGER, Y AS INTEGER, Zoom AS SINGLE)
  100.     '    IF array(0).Index + 1 > UBOUND(array) THEN array(0).Index = 0 ELSE array(0).Index = array(0).Index + 1
  101.     Frame = array(0).Index
  102.     PosXs = array(Frame).X_Start
  103.     PosXe = array(Frame).X_End
  104.     PosYs = array(Frame).Y_Start
  105.     PosYe = array(Frame).Y_End
  106.     ResX = PosXe - PosXs
  107.     ResY = PosYe - PosYs
  108.  
  109.     S& = array(Frame).Source&
  110.     IF array(0).Index + 1 > UBOUND(array) THEN array(0).Index = 0 ELSE array(0).Index = array(0).Index + 1
  111.     _PUTIMAGE (X, Y)-(Zoom * (X + ResX), Zoom * (Y + ResY)), S&, 0, (PosXs, PosYs)-(PosXe, PosYe)
  112.     _DISPLAY
  114.  
  115.  
  116.  
  117. SUB VideoLoad (Array() AS FRAME, Source AS LONG, FramesX AS INTEGER, FramesY AS INTEGER, ResFrameX AS INTEGER, ResFrameY AS INTEGER, CorrX AS _BYTE, CorrY AS _BYTE)
  118.     x = CorrX: y = CorrY
  119.     FOR T = 0 TO FramesX * FramesY - 1
  120.         REDIM _PRESERVE Array(T) AS FRAME
  121.         IF x + ResFrameX + CorrX > _WIDTH(Source&) THEN x = CorrX: y = y + ResFrameY + CorrY
  122.         '  IF Y + ResFrameY + CorrY > _HEIGHT(Source&) THEN EXIT SUB
  123.         Array(T).Source = Source&
  124.         Array(T).X_Start = x + CorrX
  125.         Array(T).Y_Start = y + CorrY
  126.         Array(T).X_End = x + ResFrameX + CorrX
  127.         Array(T).Y_End = y + ResFrameY + CorrY
  128.         x = x + ResFrameX + CorrX: 'IF X > _WIDTH(Source&) THEN X = CorrX: Y = Y + ResFrameY + CorrY
  129.     NEXT T
  131.  
  132. 'for perfect work you need picture with one color in background. Picture is in memory after load, so you can use it as source for collision detection.
  133. 'let say, if you draw picture to background _RGB32(255,255,254), then human see no difference between this and _RGB32(255,255,255). But computer yes.
  134.  
  135. FUNCTION DetectRex& (x AS INTEGER, y AS INTEGER, source AS LONG) 'this function READ NOT SCREEN but loaded image!
  136.     DIM O AS _MEM
  137.     O = _MEMIMAGE(source&)
  138.     _MEMGET O, O.OFFSET + IN4&(x, y), value&
  139.     R = _RED32(value&)
  140.     G = _GREEN32(value&)
  141.     B = _BLUE32(value&)
  142.     IF R >= 200 AND G >= 200 AND B >= 200 THEN DetectRex& = 0 ELSE DetectRex& = 1 ' > 200 because color > 200 is set as transparent with setalpha and are not visible. Its background rex picture.
  143.     _MEMFREE O
  145.  
  146.  
  147.  
  148.  
  149.  
  150.  
  151.  
  152.  
  153.  
  154.  
  155.  
  156.  
  157. 'there are two way how do it: slow, used POINT or fast, used MEM. First demo show you slow method:
  158.  
  160.     IF x < 220 AND y < 75 THEN
  161.         IF POINT(x, y) = 15 THEN white = 15 ELSE white = 0 '1 = true, is collision, zero = false for collision
  162.     END IF
  164.  
  165. FUNCTION MEM_White (x AS INTEGER, y AS INTEGER, source AS LONG)
  166.     DIM M AS _MEM, Value AS _UNSIGNED _BYTE 'FOR 256 colors only! (in 32 bites muss Value be LONG type)
  167.     M = _MEMIMAGE(source)
  168.     _MEMGET M, M.OFFSET + IN&(x, y), Value
  169.     IF Value = 15 THEN MEM_White = 1 ELSE MEM_White = 0
  170.     _MEMFREE M
  172.  
  173. FUNCTION IN& (x AS INTEGER, y AS INTEGER) 'for 256 color only! (in 32 bites you read not ONE, but FOUR BYTES)
  174.     IN& = (y * _WIDTH) + x
  176.  
  177. FUNCTION IN4& (x AS INTEGER, y AS INTEGER) 'for 256 color only! (in 32 bites you read not ONE, but FOUR BYTES)
  178.     IN4& = 4 * ((y * _WIDTH) + x)
  180.  
  181.  
  182.  
Title: Re: Collision Detection
Post by: bplus on June 10, 2018, 11:13:26 am
Collision detection between circles pretty easy and quite useful but allot of images are rectangular and collision detection between two rectangles can be quite useful also.

Of course what Petr has (I think) collision detection of actual image is quite complex whew! nice...

Johnno, I took you excellent collision detection for 2 set rectangles and generalized it for rectangular images using top left x, y and the image width and height for a reusable procedure.

I also added notes where I thought your code might be improved and some Johnno style humor!:
Code: QB64: [Select]
  1. _TITLE "Collision of Rectangular Images started by Johnno mod b+ 2018-06-10"
  2. '^^^^^^^^^^^^^^^^^^^^^^^^ no () needed but must call before SCREEN line around the string title
  3.  
  4. '
  5. '   Collision - Test 1  orig by johnno copied and mod b+ 2018-06-10
  6. '
  7. '   Bounding Box
  8. '
  9. ' 2018-06-10 mod by B+ change for x, y, w, h of images
  10. ' by readjusting all the variables and use STEP for box drawing
  11. ' Generalize the specific gosub routine from this one app so can reuse IN ANY APP using sprites / tiles / images
  12.  
  13. SCREEN _NEWIMAGE(800, 600, 32) '<<< something more standard center is 400, 300
  14.  
  15. ' sprites / tiles / images are typically referred to by their left top corner ie X, Y  and their width and height
  16.  
  17. 'lets do the height and width first
  18. box1Width = 400 '<<< mod add this instead of  calculation of box1Right
  19. box1Height = 100 '<<< mod add this instead of calculation of box1Bottom
  20. 'now center box
  21. box1Left = 400 - box1Width / 2 'same as box1X
  22. 'box1Right = 370 '100 width
  23. box1Top = 300 - box1Height / 2 'same as box1Y
  24. ' box1Bottom = 290 '100 height
  25.  
  26. mouseboxWidth = 50 '<<< mod add these constants
  27. mouseboxHeight = 40 '<<< mod add these constants
  28.  
  29. f& = _RGB32(255, 255, 255)
  30. b& = _RGB32(0, 0, 0)
  31.  
  32. DIM hey$(10) 'hey if boxes could talk....
  33. hey$(0) = "Hey!"
  34. hey$(1) = "I beg your pardon."
  35. hey$(2) = "Bang!"
  36. hey$(3) = "Yikes!"
  37. hey$(4) = "Ouch!"
  38. hey$(5) = "Watch where you are going."
  39.  
  41.     k$ = INKEY$
  42.     WHILE _MOUSEINPUT: WEND '<<< this is all the loop needed for mouse input
  43.     CLS
  44.     LINE (box1Left, box1Top)-STEP(box1Width, box1Height), _RGB32(255, 255, 255), BF
  45.  
  46.     'box2left = _MOUSEX - 50
  47.     'box2top = _MOUSEY - 50
  48.     'box2right = box2left + 100
  49.     'box2bottom = box2top + 100
  50.  
  51.     mouseboxX = _MOUSEX - mouseboxWidth / 2
  52.     mouseboxY = _MOUSEY - mouseboxHeight / 2
  53.     LINE (mouseboxX, mouseboxY)-STEP(mouseboxWidth, mouseboxHeight), _RGB32(255, 128, 0), BF '<<< use step with width and height
  54.  
  55.     'GOSUB collide   <<< generalize this to a call to a reuseable routine
  56.  
  57.     IF collision%(box1Left, box1Top, box1Width, box1Height, mouseboxX, mouseboxY, mouseboxWidth, mouseboxHeight) = 1 THEN
  58.         COLOR _RGB32(130, 0, 85), _RGB32(255, 255, 255)
  59.         r$ = hey$(INT(RND * 6))
  60.         _PRINTSTRING (box1Left + (box1Width - LEN(r$) * 8) / 2, 292), r$
  61.         COLOR f&, b&
  62.         lim = 1
  63.     ELSE
  64.         lim = 50
  65.     END IF
  66.     _DISPLAY
  67.     _LIMIT lim '<<< save the fan
  68. LOOP UNTIL k$ = CHR$(27)
  69.  
  70. 'collide:
  71. 'IF (box1bottom < box2top) OR (box1top > box2bottom) OR (box1left > box2right) OR (box1right < box2left) THEN
  72. '    collision = 0
  73. 'ELSE
  74. '    collision = 1
  75. 'END IF
  76. 'RETURN
  77.  
  78. FUNCTION collision% (b1x, b1y, b1w, b1h, b2x, b2y, b2w, b2h)
  79.     ' yes a type smaller than integer might be used
  80.     ' x, y represent the box left most x and top most y
  81.     ' w, h represent the box width and height which is the usual way sprites / tiles / images are described
  82.     ' such that boxbottom = by + bh
  83.     '        and boxright = bx + bw
  84.     'so the specific gosub above is gerealized to a function procedure here!
  85.     IF (b1y + b1h < b2y) OR (b1y > b2y + b2h) OR (b1x > b2x + b2w) OR (b1x + b1w < b2x) THEN
  86.         collision% = 0
  87.     ELSE
  88.         collision% = 1
  89.     END IF
  91.  
  92.  
Title: Re: Collision Detection
Post by: johnno56 on June 10, 2018, 06:44:43 pm
The coding looks some-what familiar... lol but I like your sense of humour... A little whacky but leaning towards absolute bug-nuts...

Quick question: You used "&" in a few of the variables, what are the advantages/disadvantages, of using or not using the ampersand?

ps: I kind of like using the "if" instead of branching off to a routine. I suppose the difference would be a slight improvement in efficiency. The routine is being access 'all the time' as the "If" is conditional. Cool

Nice example.

I would be curious to find out how to do a 'pixel perfect' collision system (or even polygon) and compare the performance effects... Do you know of such a system?

J

ps: Today (June 11th), for we in 'The Colonies', are enjoying a Public Holiday. Queen's Birthday. Even though her birthday was in April... lol.. Feet up; Relaxing; Coding as we speak... Bliss.

pps: "Save the fan"? Looks like a reference to "Skyhigh" to me... lol
Title: Re: Collision Detection
Post by: bplus on June 10, 2018, 08:59:13 pm
Hi Johnno,

The & is for long integer type best used with _RGB32 color variables, use && if want alpha too ie _RBGA32().

I don't know if the collision function is more efficient than a gosub but it is easier to reuse in other apps. So now we have it ready to go with this fun code tester.

Pixel perfect collision??? maybe from what Petr has brought here today? I have to look into that.

Happy holidays or tell the queen happy birthday for me. ;D

"Save the fan", I meant don't over heat the CPU. Use a _LIMIT after _DISPLAY in loops to control the maximum number of loops to run per second.
Title: Re: Collision Detection
Post by: johnno56 on June 11, 2018, 12:25:46 am
Cool. Thanks for the clarification.

I too will keep researching pixel perfect. Looking into Box2D but uncertain that any part of it can be coded for QB64. I think Box2D is written in C++. But some of those libraries could be handy... *sigh* A nice simple physics engine would be cool...

In regards to the Queen: Our families are not on speaking terms ever since our ancestors left the UK in 1852...

Concentration on coding is shot to pieces at the moment... Grandkids are visiting... Say no more...

J

Title: Re: Collision Detection
Post by: Petr on June 11, 2018, 03:39:44 pm
I write today program which demonstrate better collision detection. After start it show you picture, press any key. Then it show you detected borders after then is running snow demo, that use this collision detection. No such any physics in. Source is commented.

Code: QB64: [Select]
  1.  
  2. TYPE Borders '                                          this is "struct" for array Borders. This array conatains borders between image and background. It is my first vesion for collision detection.
  3.     X AS INTEGER
  4.     Y AS INTEGER
  5.     Clr AS LONG
  6.     maxX AS INTEGER
  7.     minX AS INTEGER
  8.     MaxY AS INTEGER
  9.     MinY AS INTEGER
  11.  
  12. imag& = _LOADIMAGE("z.jpg", 32) '                       load example picture (downloaded from google)
  13. image& = filter&(imag&, 150, 150, 150, 255, 255, 255) ' this is exemplary function. Downgrade background colors in set range to set RGB32 value: First 3* 255 are RGB inputs, next 3*230 are RGB outputs
  14. SCREEN image&: SLEEP '                                  'It depends a lot on the correct setting of this function if the source image does not contain clear boundaries for proper border detection.
  15.  
  16. REDIM S(0) AS Borders
  17. _SOURCE image&
  18.  
  19. Border S(), image&, _RGB32(255, 255, 255) '            function based on ONE color in background. Write image borders to array, writed for 256 colors and or truecolor, but tested for truecolor only
  20. '                                                      parameter in function is background color in source image
  21. B_Output& = _NEWIMAGE(800, 600, 32)
  22. SCREEN B_Output&
  23. LOCATE 1, 30: PRINT "This is Border SUB output:" '    program show you detected and to array writed borders
  24. FOR T = LBOUND(s) TO UBOUND(s)
  25.     PSET (S(T).X, S(T).Y)
  27. LOCATE 22, 1: PRINT "press key"
  29. PRINT "This is picture, for which are border created:"
  30. _SETALPHA 0, _RGB32(255, 255, 255) TO _RGB32(240, 240, 240), image& 'set white as transparent, but as you can see, here is problem, if area in picture use the same color as tranpsarent
  31. _PUTIMAGE (0, 0), image&
  32. LOCATE 22, 1: PRINT "now you can see borders and image. It is not perfect, because picture contains not just"
  33. LOCATE 23, 1: PRINT "_RGB32(255,255,255) White color but some different. Press key for test collision detect"
  35. CLS '                                                                      and here is time to try it in program :-D
  36.  
  37. TYPE par '                                                                 struct for snow: X = axis X
  38.     x AS INTEGER '                                                                          Y = axis Y
  39.     y AS INTEGER '                                                                          MY is speed to get down
  40.     mY AS _UNSIGNED _BYTE '                                                                 S is size
  41.     S AS SINGLE '                                                                           Time = delay to restart particle
  42.     time AS DOUBLE
  44. CONST part = 100 '                                                       total particles for snow in use is 100
  45. DIM SHARED particles(part) AS par
  46.  
  47. _PUTIMAGE (300, 200), image& '                                           set transparent picture to screen
  50. O = _MEMIMAGE(0) '                                                       O is pointer to memory area, where current screen (0) placed
  51. wht& = _RGB32(255, 255, 255) '                                           white color
  52. blk& = _RGB32(0, 0, 0) '                                                 black color
  54.  
  55.     FOR a = 1 TO part '                                                  do for all snow particles
  56.         IF particles(a).y < 1 OR particles(a).y > 580 THEN '             conditions prevents particles to go out from screen
  57.             particles(a).x = 800 * RND + 1
  58.             particles(a).y = 20 * RND + 1
  59.             particles(a).mY = 1 + RND * 15
  60.         END IF
  61.         particles(a).S = particles(a).y / 60
  62.         IF particles(a).y < 550 AND particles(a).y > 30 AND particles(a).x > 50 AND particles(a).x < 750 THEN 'conditions prevents MEMORY REGION OUT OF RANGE, because is _MEM used for better speed
  63.             IF particles(a).mY > 0 THEN M_Circle particles(a).x, particles(a).y, particles(a).S, _RGB32(0, 0, 0), _RGB32(0, 0, 0), _DEST 'Circles created using _MEM
  64.         END IF
  65.  
  66.         particles(a).y = particles(a).y + particles(a).mY
  67.         IF Collis_Detect(particles(a).x, particles(a).y, S(), 300, 200) THEN particles(a).mY = 0 '                                                  if is collision detected, particle stay on place
  68.  
  69.         FOR T = 0 TO part
  70.             IF ABS(particles(a).x - particles(T).x) < 10 AND ABS(particles(a).y - particles(T).y) < 10 AND particles(T).mY = 0 THEN
  71.                 particles(a).mY = 0
  72.             END IF
  73.         NEXT T
  74.         IF particles(a).time > 0 AND particles(a).time < TIMER THEN
  75.             M_Circle particles(a).x, particles(a).y, particles(a).S, _RGB32(255, 255, 255), _RGB32(255, 255, 255), _DEST 'place after paticle draw black
  76.             particles(a).x = RND * 750: particles(a).y = RND * 20: particles(a).time = 0: particles(a).mY = 1 + RND * 15 'after random time limit restart particle
  77.         END IF
  78.         IF particles(a).y < 550 AND particles(a).y > 30 AND particles(a).x > 50 AND particles(a).x < 750 THEN 'if is particle on screen position usable for MEM,
  79.             IF particles(a).mY > 0 THEN M_Circle particles(a).x, particles(a).y, particles(a).S, _RGB32(128, 128, 128), _RGB32(255, 255, 255), _DEST ELSE M_Circle particles(a).x, particles(a).y, particles(a).S, _RGB32(255, 255, 255), _RGB32(255, 255, 255), _DEST: IF particles(a).time = 0 THEN particles(a).time = CDBL(TIMER + 1 + RND * 5) ' set time limit for restart particle
  80.             particlesLong = UBOUND(particles) '                                                                so if is collision, My is set to zero, so particle is stoped and particle border then is white draw
  81.         END IF
  82.         _DISPLAY
  83.     NEXT
  85.  
  86.  
  87. FUNCTION Collis_Detect (Ex AS INTEGER, Ey AS INTEGER, s() AS Borders, x AS INTEGER, y AS INTEGER)
  88.     SHARED particles() AS par
  89.     'Ex and Ey are enemy coordinates, s is array contains picture border, x and y is who is picture placed / left uppon corner
  90.     minX = s(0).minX 'can be used for quadric standard collision detection, this four values return picture X start, X end, Y start and Y end
  91.     maxX = s(0).maxX
  92.     minY = s(0).MinY
  93.     maxY = s(0).MaxY
  94.  
  95.     FOR CD = LBOUND(s) TO UBOUND(s)
  96.         i = i + 1
  97.         IF i > part THEN i = 1
  98.         '            IF s(CD).X + Ex = s(CD).X + x OR s(CD).Y + Ey = s(CD).Y + y THEN Collis_Detect = 1 ELSE Collis_Detect = 0
  99.         IF ABS((s(CD).X + x) - Ex) < particles(i).S AND ABS((s(CD).Y + y) - Ey) < particles(i).S THEN Collis_Detect = 1: EXIT FUNCTION ELSE Collis_Detect = 0 'Here it read radius from particles.s
  100.     NEXT '                                                                       its radius size and then if conditions are valid return 0 for no collis or 1 for collis. ABS is always positive output
  101.     '                                                                            (  ABS (20 - 80) = 60  ) so i muss not driving with SGN sign for values
  103.  
  104.  
  105.  
  106.  
  107. SUB Border (array() AS Borders, Source AS LONG, Background_Color AS _UNSIGNED LONG) 'own border detection sub
  108.     _DEST Source&
  109.     minX = _WIDTH(Source&)
  110.     minY = _HEIGHT(Source&)
  111.     DIM M AS _MEM '32 bytova promenna                                                                         '  MEM values are 32 BYTES long,
  112.     M = _MEMIMAGE(Source&) '                                                                                     M is pointer to memory with image content
  113.     SELECT CASE _PIXELSIZE(Source&) '                                                                           select if image is 256 colored, 8 bit (1 byte for pixel) or 32 bit colored (4 byte for pixel)
  114.         CASE 0: END 'not writed for text mode yet                                                                0 is for text mode, then this screen contains cells 8 * 16 pixels, one cell has value one BYTE
  115.         CASE 1: '    for 256 colors image
  116.             REDIM Value AS _UNSIGNED _BYTE, OldValue AS _UNSIGNED _BYTE '                                       because i need read value directly from memory, muss set correct type first - basicaly are
  117.             FOR y = 0 TO _HEIGHT(Source&) - 1 '                                                                 all varibles set to SINGLE (4 byte long)
  118.                 FOR x = 0 TO _WIDTH(Source&) - 1
  119.                     OldValue = Value
  120.                     _MEMGET M, M.OFFSET + IN&(x, y), Value '                                                    is the same as POINT but very  more faster!  _MEMGET is as POINT for read color value,
  121.                     '                                                                                           _MEMPUT is the same as POINT for writing color value. In use with mem muss be correct type and offset set.
  122.                     IF Value = Background_Color AND OldValue <> Background_Color OR Value <> Background_Color AND OldValue = Background_Color THEN
  123.                         GOSUB rozsah '                                                                          subprogram continuously compares values for MinX, MaxX, MinY and MaxY
  124.                         i = i + 1
  125.                         REDIM _PRESERVE array(i) AS Borders '                                                   this command increases the field value without losing the field contents // to i size
  126.                         array(i).X = x
  127.                         array(i).Y = y
  128.                         array(i).Clr = Value
  129.                     END IF
  130.                     IF y > 0 THEN _MEMGET M, M.OFFSET + IN&(x, y - 1), Value '                                  condition for preveting MEMORY REGION OUT OF RANGE and read current color value on X, Y
  131.                     IF Value = Background_Color AND OldValue <> Background_Color OR Value <> Background_Color AND OldValue = Background_Color THEN
  132.                         i = i + 1 'This condition: If current color is the same as background and previous color is different than background or above, write this coordinates to array. Easy trick.
  133.                         REDIM _PRESERVE array(i) AS Borders '                                                   this command increases the field value without losing the field contents // to i size
  134.                         array(i).X = x
  135.                         array(i).Y = y '                                                            program line 117 control colors in row, program line 126 control colors in column
  136.                         array(i).Clr = Value
  137.                     END IF
  138.             NEXT x, y
  139.  
  140.         CASE 4: 'for 32 bit screen                                                                ' this block is the same for truecolor (4 byte blocks)
  141.             REDIM Value4 AS LONG, OldValue4 AS LONG '                                               program lines 142 and 153 control and writing borders to array
  142.             FOR y = 0 TO _HEIGHT(Source&) - 4
  143.                 FOR x = 0 TO _WIDTH(Source&) - 4
  144.                     OldValue4& = Value4&
  145.                     _MEMGET M, M.OFFSET + IN&(x, y), Value4&
  146.  
  147.                     IF Value4& = Background_Color AND OldValue4& <> Background_Color OR Value4& <> Background_Color AND OldValue4& = Background_Color THEN
  148.                         GOSUB rozsah
  149.                         i = i + 1
  150.                         REDIM _PRESERVE array(i) AS Borders
  151.                         array(i).X = x
  152.                         array(i).Y = y
  153.                         array(i).Clr = Value4&
  154.                     END IF
  155.  
  156.                     IF y > 0 THEN _MEMGET M, M.OFFSET + IN&(x, y - 1), Value4&
  157.  
  158.                     IF Value4& = Background_Color AND OldValue4& <> Background_Color OR Value4& <> Background_Color AND OldValue4& = Background_Color THEN
  159.                         i = i + 1
  160.                         REDIM _PRESERVE array(i) AS Borders
  161.                         array(i).X = x
  162.                         array(i).Y = y
  163.                         array(i).Clr = Value4&
  164.                     END IF
  165.                     nic:
  166.             NEXT x, y
  167.     END SELECT
  168.     _DEST 0
  169.     array(0).minX = minX '                                                                           to zero position in array are writed image width and height for
  170.     array(0).maxX = maxX '                                                                           possibillity quadric collision detection
  171.     array(0).MinY = minY
  172.     array(0).MaxY = maxY
  173.  
  174.     EXIT SUB
  175.     rozsah:
  176.     IF minX > x AND x > 0 THEN minX = x
  177.     IF minY > y AND y > 0 THEN minY = y
  178.     IF maxX < x THEN maxX = x
  179.     IF maxY < y THEN maxY = y
  180.     RETURN
  182.  
  184.     IN& = _PIXELSIZE(_SOURCE) * ((_WIDTH * y) + x) '                                                  function return offset for MEM functions. Copyed from Steve McNeill
  186.  
  187. FUNCTION filter& (image AS LONG, Ri, Gi, Bi, Ro, Go, Bo) '                                            Function has the task of making the background of the specified color and reducing the
  188.     DIM f AS _MEM '                                                                                   background color unevenness to make the best possible image border detection
  189.     f = _MEMIMAGE(image&)
  190.     '   filter& = _MEMNEW(_WIDTH(image&) * _HEIGHT(image&) * _PIXELSIZE(image&)) '                    Here is one bug for developers. Uncomment and give C++ compilation error. I know why, so just for info. :-D With love :-D
  191.     filter& = _NEWIMAGE(_WIDTH(image&), _HEIGHT(image&), 32)
  192.     DIM GG AS _MEM
  193.     GG = _MEMIMAGE(filter&)
  194.     _SOURCE image&
  195.     _DEST image& '                                                                                    next ask for developers. Comment DEST on this line and start it. You give HALF picture. Why?
  196.     SELECT CASE _PIXELSIZE(image&)
  197.         CASE 4
  198.             DIM clr AS LONG
  199.             choice& = _RGBA32(Ro, Go, Bo, 255)
  200.             FOR y = 0 TO _HEIGHT(image&) - 4
  201.                 FOR x = 0 TO _WIDTH(image&) - 4
  202.                     _MEMGET f, f.OFFSET + IN&(x, y), clr&
  203.                     R = _RED32(clr&)
  204.                     G = _GREEN32(clr&)
  205.                     B = _BLUE32(clr&)
  206.                     A = _ALPHA32(clr&)
  207.                     IF R > Ri AND G > Gi AND B > Bi AND A > 200 THEN _MEMPUT GG, GG.OFFSET + IN&(x, y), choice& ELSE _MEMPUT GG, GG.OFFSET + IN&(x, y), clr&
  208.     NEXT x, y: END SELECT
  209.  
  210.     _MEMFREE f
  211.     _MEMFREE GG
  212.     _FREEIMAGE image&
  214.  
  215.  
  216.  
  217. SUB M_Circle (X AS INTEGER, Y AS INTEGER, Radius AS INTEGER, Circuit_Color AS LONG, Fill_Color AS LONG, Dest AS LONG) 'this is (very badly) sub for creating fill circles using MEM. Much better be
  218.     DIM M AS _MEM '                                                                                                    SteveMCNeill LINE modification for it. MEM__Line i have already writed....
  219.     M = _MEMIMAGE(Dest&)
  220.     FOR rds = 0 TO Radius
  221.         IF rds = Radius THEN clr& = Circuit_Color& ELSE clr& = Fill_Color&
  222.         FOR cir = 0 TO 6.28 STEP .1
  223.             _MEMPUT M, M.OFFSET + IN&(X + SIN(cir) * rds, Y + COS(cir) * rds), clr&
  224.     NEXT cir, rds
  225.     _MEMFREE M
  227.  

use attached picture, function filter& is set for this image (source code line 13)
Title: Re: Collision Detection
Post by: johnno56 on June 11, 2018, 05:40:54 pm
Cool... That seems to be a quite unique collision system. Nicely done!

J
Title: Re: Collision Detection
Post by: TempodiBasic on June 13, 2018, 09:09:56 am
Collision Detection
 a very important and difficult issue...

I must say these feedback...

Hi Johnno56
your first code makes a bug after pressing ESC key.... (IMHO for the absence of END between LOOP UNTIL and collide: )

Hi Petr
I find your method very interesting....
If i put the mouse pointer on the body of the horse at the position of the leg of the man I get a switching response Collision Horse/ NO Collision Horse....  maybe the issue can be in the way that the image in movement is built up.
See Images attached
Title: Re: Collision Detection
Post by: Petr on June 13, 2018, 09:41:01 am
Hi TempodiBasic,

it's okay, it works on that principle. I try to think of such a procedure so the computer does not burden too much. So far, I have been doing a speed test for DIM and MEM. The difference is small for a small volume of data, for large volumes but up to 50 percent. This is related to the fact that I am trying to find the fastest method (which I will be able to write with current knowledge). What I have forgotten is such an important little thing. It's a trifle without which we do not move. This function not only has to return the state that a collision has occurred. That is not enough. She must also return the value from where.
Title: Re: Collision Detection
Post by: codeguy on June 14, 2018, 06:01:13 pm
QB64 is down or I'd recommend a look at collding text for rectangular detection and NSpace for polygonal.
Title: Re: Collision Detection
Post by: Unseen Machine on June 23, 2018, 07:57:18 pm
Hi,

GDK has the best (basic) collision detection made so far. It uses Bounding Cirlces or Rectangles. The rectangle collision detection can even create autosized rectangles based on the image used and also rotate with the image rather than resizing! It doesnt support pixel perfect collisions yet as i've always found implementing that really slows down the program...best bet is scaled rectangles in my opinion.

If you wanna go another route then maybe look into SAT (Seperated Axis Therom) collision detection (implementing that has always foiled me!). I looked into porting Box2D a few years ago and that was even more of a mission! Also, im sure that the community could come up with something comparable without resorting to DECLARE LIBRARY!

Unseen

Title: Re: Collision Detection
Post by: johnno56 on June 24, 2018, 12:50:46 am
GDK?
Title: Re: Collision Detection
Post by: Petr on June 24, 2018, 04:41:11 am
Thank you, I'm glad to look at it. I'm not an undergraduate, so I first had to find out what you mean by the triangular / circle method. I found this in a bachelor's thesis on this subject, so again i know more.

Hi Johhno56, GDK is Unseen Machine´s library downloadable here: https://www.qb64.org/forum/index.php?topic=284.0;topicseen
Title: Re: Collision Detection
Post by: Petr on June 24, 2018, 06:14:48 am
A little beyond the thema - function for detecting collisions between point and ellipse:

Code: QB64: [Select]
  1. 'elipse collision detection for point
  3. LET CenterX = 160: LET CenterY = 100: LET A = 40: LET B = 20
  4.  
  5. FOR F = 0 TO _PI(2) STEP .01
  6.     PSET (CenterX + SIN(F) * A, CenterY + COS(F) * B)
  8.  
  11.     LOCATE 1, 1: PRINT Ellipse(_MOUSEX, _MOUSEY, CenterX, CenterY, A, B)
  14.  
  15.  
  16. FUNCTION Ellipse (X&, Y&, CX&, CY&, A&, B&)
  17.     XY## = (((X& - CX&) ^ 2) / A& ^ 2) + (((Y& - CY&) ^ 2) / B& ^ 2)
  18.     IF XY## <= 1.1 THEN Ellipse = 1 ELSE Ellipse = 0
  20.  
  21.  
Title: Re: Collision Detection
Post by: TempodiBasic on June 24, 2018, 06:23:31 am
IMHO
GDK, maybe is it Game Development Kit ?  Like that other library of Terry Ritchie.
They have different structures and GDK has maintenance, about Terry Ritchie's Library it seems discontinued....
I have a previous old version of these library on my Pc (TOSHIBA)
Quote
'\\ UnseenGDK Core v1.4 - Updated March 3rd 2015
'// Created By John Onyon a.k.a Unseen Machine
'// Optimistation by CodeGuy
'// ScanKeys% function by Cypherium
'// Image rotation function by Galleon
'// Rotated rectangle collisions by Richard Notley

from Unseen was coming also VQB02 in the same package...
(IMHO  Visual QB??? but there is nothing like mouseBuilding Interface or Structure of a program...)
a library to build application windowing and manage input from mouse and keyboard
and a demo .... MacDock.BAS

Quote
'// VQB v.02 - By John Onyon a.k.a Unseen Machine
'// VQB_01 programs are NOT comaptible with this version.
.... I don't know if this project is still in being or discontinued.... but of his child must talk at first the father if he will!

Title: Re: Collision Detection
Post by: bplus on June 24, 2018, 09:50:42 am
Quote
GDK, maybe is it Game Development Kit ? 

Dang! That's a great theory even if it were incorrect.

No, it's too good to be wrong? :D
Title: Re: Collision Detection
Post by: bplus on June 24, 2018, 10:26:24 am
The flaw of this theory is this:

Why name it with _Dev for .bm file?

but in fact in the last posting he had removed _Dev from the library file name. In fact, I had to fix my copy of his code to match the first .bm I downloaded.
Title: Re: Collision Detection
Post by: bplus on June 24, 2018, 10:32:03 am
I suppose these are developments from having your skull on fire!

BTW, VQB does sound like another excellent name of something!
Title: Re: Collision Detection
Post by: TempodiBasic on June 24, 2018, 04:07:14 pm
Hi Petr
fine your sample but so much static....
so I have added a little movement in it

see here
 
Code: QB64: [Select]
  1. 'elipse collision detection for point
  2. SCREEN 13 'w320xh200 I don't remember well dimensions of old legacy screen mode :-)
  3. LET CenterX = 80: LET CenterY = 100: LET A = 40: LET B = 20
  4. LET MoveX = 1: LET MoveY = 1
  5.  
  8. ' output engine (Not mine) :-)
  9.     FOR F = 0 TO _PI(2) STEP .01
  10.         PSET (CenterX + SIN(F) * A, CenterY + COS(F) * B)
  11.     NEXT F
  12.  
  13. ' refreshing after an elapsed time  
  14.     _DELAY 0.02
  15.     CLS
  16. ' logic engine to let stay ellipse in the screen
  17.     IF (CenterX - A <= 0) THEN
  18.         MoveX = 1
  19.     ELSE
  20.         IF (CenterX + A >= 320) THEN MoveX = -1
  21.     END IF
  22.  
  23.     IF (CenterY - B <= 0) THEN
  24.         MoveY = 1
  25.     ELSE
  26.         IF (CenterY + B >= 200) THEN MoveY = -1
  27.     END IF
  28. ' logic engine calculating new position of ellipse
  29.     CenterX = CenterX + MoveX 'centerx++/centerx--
  30.     CenterY = CenterY + MoveY 'centery++/ centery--
  31.  
  32.     LOCATE 1, 1: PRINT Ellipse(_MOUSEX, _MOUSEY, CenterX, CenterY, A, B)
  35.  
  36.  
  37. FUNCTION Ellipse (X&, Y&, CX&, CY&, A&, B&)
  38.     XY## = (((X& - CX&) ^ 2) / A& ^ 2) + (((Y& - CY&) ^ 2) / B& ^ 2)
  39.     IF XY## <= 1.1 THEN Ellipse = 1 ELSE Ellipse = 0
  41.  

@Bplus
hey boy but  are you talking about my brain or my skull? :-(( For now weather is hot but not such so hot!

Quote
I suppose these are developments from having your skull on fire!

a skull can be a head without a brain into it.... just a zombie head :-)
I cannot imagine what can be thought in a head on fire... and moreover in a skull on fire....
like this https://tse3.mm.bing.net/th?id=OIP.tONt-rsCjWByGGeqc9QaiQHaHa&pid=15.1&P=0&w=300&h=300 (https://tse3.mm.bing.net/th?id=OIP.tONt-rsCjWByGGeqc9QaiQHaHa&pid=15.1&P=0&w=300&h=300)
or this one  http://www.desktopanimated.com/img/Preview/FireSkull3.jpg (http://www.desktopanimated.com/img/Preview/FireSkull3.jpg)
or just this last http://3.bp.blogspot.com/_6GGcln-fE78/TCXYCwNk2NI/AAAAAAAAAWk/mwmCK9izrG0/s1600/Fire+Skull.jpg (http://3.bp.blogspot.com/_6GGcln-fE78/TCXYCwNk2NI/AAAAAAAAAWk/mwmCK9izrG0/s1600/Fire+Skull.jpg)

Ok I have found the just SkullOnFire... it is attached
Title: Re: Collision Detection
Post by: Petr on June 24, 2018, 04:36:02 pm
Hi TempoDiBasic, thank you. Now it's nicer. I've been looking at your source, and I have never seen the skull picture now, so I say, what it would be. BPlus had some sort of muse :-D mood today, as I read on the forum. He gave his passage full of muse. And my muse is sleeping today: -D
Title: Re: Collision Detection
Post by: bplus on June 24, 2018, 06:37:39 pm
For burning skull, I was talking about unseen machine's latest avatar!

We were talking about the naming of his GDK system and I was wondering why he named his .BM file unseenGDK_Dev.bm which translates to unseen Game Develoment Kit _ Development.bm the word "development" looked a bit redundant.
Title: Re: Collision Detection
Post by: Unseen Machine on June 24, 2018, 06:48:41 pm
_DEV is cause it is the Development version, being edited, its so i dont get confused!

VQB is now moving into v.4, ill be putting it out soon.

Unseen
Title: Re: Collision Detection
Post by: bplus on June 24, 2018, 07:04:57 pm
;-))  I see, very logical, now.

Very curious about VQB!
Title: Re: Collision Detection
Post by: Petr on June 27, 2018, 05:39:22 pm
This is only the final part of the program, which I will release as long as I finish:

WARNING FOR BPLUS! FULLSCREEN IS USED :-D
Code: QB64: [Select]
  1. 'IF o theraphy :-D (how, for hell write correct conditions?)
  2.  
  3. object0: '0 are empty places, 1 are points
  4. DATA 0,0,0,0,0
  5. DATA 0,1,1,1,1
  6. DATA 0,0,0,0,1
  7. DATA 1,1,1,1,1
  8. DATA 1,0,0,0,0
  9.  
  10. DIM O(4, 4)
  11. 'load object data to array for this example. This values return next program i send here soon as possible.
  12. FOR ObjectLoad = 0 TO 24
  13.     READ value
  14.     O(x, y) = value
  15.     x = x + 1: IF x > 4 THEN x = 0: y = y + 1
  17.  
  18. SCREEN _NEWIMAGE(320, 240, 256): _FULLSCREEN
  19. 'show what is in array
  20. FOR y = 0 TO 4
  21.     FOR x = 0 TO 4
  22.         IF O(x, y) = 1 THEN PSET (160 + x, 100 + y), 14
  23. NEXT x, y
  24.  
  25. 'now own collision detection form. If Object 1 is in quad Object 2 or above, then:
  26. 'example - first row: first row is 5 x empty pixel. Let say, object 2 is comming to this area to third pixel:
  27.  
  28. 'original: 0,0,0,0,0    new: 0,0,1,0,0 - beacause in this row for Object1 are zeros, is none collision.
  29.  
  30. 'If object1 go next 1 pixel down, second row for Object1 is: 0,1,1,1,1 - and now is comming to third position where but is 1. Also is object collision.
  31.  
  32. 'so this programmable:
  33. Object1X = 160
  34. Object1Y = 100
  38.         Object2X = _MOUSEX
  39.         Object2Y = _MOUSEY
  40.     WEND
  41.     CLS
  42.     FOR y = 0 TO 4
  43.         FOR x = 0 TO 4
  44.             IF O(x, y) = 1 THEN
  45.  
  46.                 PSET (Object1X + x, Object1Y + y), 14
  47.                 PSET (Object2X + x, Object2Y + y), 15
  48.             END IF
  49.     NEXT x, y
  50.  
  51.  
  52.     coll = 0
  53.     'first standard QUAD condition and THEN detail comparation:  (both objects are 5 x 5 pixels)
  54.     IF Object2X >= Object1X - 5 AND Object2X <= Object1X + 5 THEN
  55.         TTT = TIMER
  56.         IF Object2Y >= Object1Y - 5 AND Object2Y <= Object1Y + 5 THEN
  57.             LOCATE 1, 1: PRINT "In collision area "
  58.             FOR TY = Object1Y TO Object1Y + 4
  59.                 FOR TX = Object1X TO Object1X + 4
  60.  
  61.                     FOR tTY = Object2Y TO Object2Y + 4
  62.                         FOR tTX = Object2X TO Object2X + 4
  63.                             IF O(TX - Object1X, TY - Object1Y) = 1 AND O(tTX - Object2X, tTY - Object2Y) = 1 AND TX = tTX AND TY = tTY THEN coll = 1: GOTO E ELSE coll = 0
  64.                             'Of course, for a higher program speed, it's better to use a step higher than 1 for the shape of the object. Let's assume that your character is 60 pixels high,
  65.                             ' moving in one step by 10 pixels. Then, the enemy moves with a 10-pixel pitch, so only every ten of the pixel per circuit character is needed.
  66.             NEXT tTX, tTY, TX, TY
  67.         END IF
  68.         LOCATE 3, 1: PRINT TIMER - TTT
  69.     END IF
  70.     E:
  71.     IF coll THEN LOCATE 2, 1: PRINT "Is collision " ELSE LOCATE 2, 1: PRINT "Not collision"
  72.     _DISPLAY
  74.  
Title: Re: Collision Detection
Post by: bplus on June 27, 2018, 05:55:54 pm
Thanks for warning, I am now armed with Alt+F4 and ready for no escape. ;)

This seems like allot of work and works!
Title: Re: Collision Detection
Post by: Petr on June 27, 2018, 06:11:22 pm
Divide and rule. The digital monster was stubborn, so I had to divide it. :-D
Title: Re: Collision Detection
Post by: keybone on July 08, 2018, 01:58:51 pm
Quote from: bplus on June 10, 2018, 08:59:13 pm
The & is for long integer type best used with _RGB32 color variables, use && if want alpha too ie _RBGA32().


Actually, you could use ~& or _UNSIGNED LONG to get _RGBA32 too, will probably save a bit of memory.
Title: Re: Collision Detection
Post by: FellippeHeitor on July 08, 2018, 02:58:20 pm
Yeah, there's definitely no need for _INTEGER64 (&&) to store colors, even with transparency. Long (or unsigned long) is more than enough.
Title: Re: Collision Detection
Post by: SMcNeill on July 08, 2018, 07:16:31 pm
Quote from: FellippeHeitor on July 08, 2018, 02:58:20 pm
Yeah, there's definitely no need for _INTEGER64 (&&) to store colors, even with transparency. Long (or unsigned long) is more than enough.

Personally, I advocate *ALWAYS* using _UNSIGNED LONG for color values.  The reason should be apparent in the little code snippet below:

Code: QB64: [Select]
  1. SCREEN _NEWIMAGE(800, 600, 32)
  2. PSET (0, 0), -1 'bright white (_RGB32(255,255,255))
  3.  
  5. PRINT POINT(0, 0) 'How QB64 reports it naturally
  6. k = POINT(0, 0) 'what we'd store it as, if we store it as a LONG
  7. k1 = POINT(0, 0) 'how we'd store that value as UNSIGNED LONG
  8. PRINT k, k1 'print to illustrate the different values
  9.  
  10. IF k = POINT(0, 0) THEN PRINT "LONG TRUE" ELSE PRINT "LONG FALSE" 'and how they change behavior with IF
  11. IF k1 = POINT(0, 0) THEN PRINT "UNSIGNED LONG TRUE" ELSE PRINT "UNSIGNED LONG FALSE"

If you're going to use POINT at all in your code, make certain you compare its values against UNSIGNED LONG values.  Otherwise, you're going to end up with a lot of false results which are going to make your program harder than heck to debug and work properly in the future.
Title: Re: Collision Detection
Post by: keybone on July 09, 2018, 01:20:10 pm
Quote from: SMcNeill on July 08, 2018, 07:16:31 pm

Personally, I advocate *ALWAYS* using _UNSIGNED LONG for color values.


I agree 100%, no point in wasting space and potentially causing errors at the same time.

Maybe that guy either didnt realize about _UNSIGNED or he didnt realize that the number

signing was the only thing stopping the color value from fitting in a LONG variable.
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