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Active Forums => Programs => Topic started by: Ashish on March 30, 2019, 09:54:40 am

Title: Collision Detection in OpenGL
Post by: Ashish on March 30, 2019, 09:54:40 am
Hi everyone!
I have found an easy way to detect collision detection of cursor with object rendered with OpenGL. (https://www.opengl.org/archives/resources/faq/technical/selection.htm)
Move your cursor over the shapes.
Code: QB64: [Select]
  1. _TITLE "Move cursor on shape(s)."
  3. SCREEN _NEWIMAGE(600, 600, 32)
  4.  
  5. DECLARE LIBRARY 'external function(s)
  6.     SUB drawCube ALIAS glutSolidCube (BYVAL dsize AS DOUBLE)
  7.         SUB gluPickMatrix (BYVAL x AS SINGLE, BYVAL y AS SINGLE, BYVAL delX AS SINGLE, BYVAL delY AS SINGLE, viewport AS LONG)
  9.  
  10. type vec3
  11.         x as single
  12.         y as single
  13.         z as single
  15.  
  16. type cube
  17.         pos as vec3 'position
  18.         col as vec3 'color
  19.         rot as vec3 'rotation
  21.  
  22. DIM SHARED mouseX, mouseY, gl, collision, obj_type
  23. Dim shared cubes(10) as cube
  24. DIM SHARED selectBuffer(4) AS _UNSIGNED LONG, hits&, viewport&(4)
  25.  
  26. for i = 0 to ubound(cubes)
  27.         cubes(i).pos.x = p5random(-1 ,1)
  28.         cubes(i).pos.y = p5random(-1, 1)
  29.         cubes(i).pos.z = p5random(-0.8,0)
  30.         cubes(i).col.x = rnd : cubes(i).col.y = rnd : cubes(i).col.z = rnd
  31.         cubes(i).rot.x = p5random(0,360)
  32.         cubes(i).rot.y = p5random(0,360)
  33.         cubes(i).rot.z = p5random(0,360)
  35.  
  36.  
  37. gl = -1
  41.     mouseX = _MOUSEX: mouseY = _MOUSEY
  42.     _LIMIT 40
  43.     CLS , 1
  44.     COLOR _RGB(255, 0, 0), 1
  45.     IF hits& >= 1 THEN
  46.                 collision = selectBuffer(3)
  47.                 ? collision, hits&
  48.         ELSE
  49.                 collision = 0
  50.         end if
  52.  
  53. SUB _GL ()
  54.         static buffer(4) as _unsigned long, tmp
  55.  
  56.     IF gl = 0 THEN EXIT SUB
  57.  
  58.  
  59.     _glEnable _GL_LIGHTING
  60.     _glEnable _GL_LIGHT0
  61.     _glEnable _GL_DEPTH_TEST
  62.     _glEnable _GL_COLOR_MATERIAL
  63.  
  64.     _glLightfv _GL_LIGHT0, _GL_AMBIENT, glVec4(0.1, 0.1, 0.1, 0)
  65.     _glLightfv _GL_LIGHT0, _GL_SPECULAR, glVec4(0.8, 0.8, 0.8, 0)
  66.     _glLightfv _GL_LIGHT0, _GL_POSITION, glVec4(1, 1, 0, 0)
  67.  
  68.  
  69.     _glGetIntegerv _GL_VIEWPORT, _OFFSET(viewport&())
  70.  
  71.     _glSelectBuffer 4, _OFFSET(buffer())
  72.     dummy = _glRenderMode(_GL_SELECT)
  74.     _glPushName 0
  75.  
  76.     _glMatrixMode _GL_PROJECTION
  78.  
  79.         _glPushMatrix
  80.  
  81.     gluPickMatrix mouseX, _HEIGHT - mouseY, 1,1, viewport&()
  82.  
  83.         for i = 0 to ubound(cubes)
  84.                 _glLoadName (i+1)
  85.                 _glPushMatrix
  86.                 _glcolor3f cubes(i).col.x,cubes(i).col.y,cubes(i).col.z
  87.                 _glrotatef cubes(i).rot.x+tmp,1,0,0
  88.                 _glrotatef cubes(i).rot.y+tmp,0,1,0
  89.                 _glrotatef cubes(i).rot.z,0,0,1
  90.                 _gltranslatef cubes(i).pos.x,cubes(i).pos.y,cubes(i).pos.z
  91.                 drawCube 0.22
  92.                 _glPopMatrix
  93.         next
  94.  
  95.         _glPopMatrix
  96.  
  97.     hits& = _glRenderMode(_GL_RENDER)
  98.         selectBuffer(3) = buffer(3)
  99.  
  100.     _glMatrixMode _GL_MODELVIEW
  101.        
  102.         for i = 0 to ubound(cubes)
  103.                 _glPushMatrix
  104.                 if collision = (i+1) then _glColor3f 1,0.5,0 else _glcolor3f cubes(i).col.x,cubes(i).col.y,cubes(i).col.z
  105.                 _glrotatef cubes(i).rot.x+tmp,1,0,0
  106.                 _glrotatef cubes(i).rot.y+tmp,0,1,0
  107.                 _glrotatef cubes(i).rot.z,0,0,1
  108.                 _gltranslatef cubes(i).pos.x,cubes(i).pos.y,cubes(i).pos.z
  109.                 drawCube 0.22
  110.                 _glPopMatrix
  111.         next
  112.        
  113.     _glFlush
  114.    
  115.         tmp=tmp+1
  117.  
  118. FUNCTION p5random! (mn!, mx!)
  119.     IF mn! > mx! THEN
  120.         SWAP mn!, mx!
  121.     END IF
  122.     p5random! = RND * (mx! - mn!) + mn!
  124.  
  125. FUNCTION glVec4%& (x, y, z, w)
  126.     STATIC internal_vec4(3)
  127.     internal_vec4(0) = x
  128.     internal_vec4(1) = y
  129.     internal_vec4(2) = z
  130.     internal_vec4(3) = w
  131.     glVec4%& = _OFFSET(internal_vec4())
  133.  
Title: Re: Collision Detection in OpenGL
Post by: Petr on March 30, 2019, 11:06:29 am
This is a very useful matter. Thank you for sharing, Ashish.
Title: Re: Collision Detection in OpenGL
Post by: Ashish on March 30, 2019, 11:09:55 am
Quote from: Petr on March 30, 2019, 11:06:29 am
This is a very useful matter. Thank you for sharing, Ashish.
Thanks Petr! But remember, when I include gluPerspective() with rendering, it doesn't work. This subject need to be studied more.
Title: Re: Collision Detection in OpenGL
Post by: Petr on March 30, 2019, 11:22:02 am
Quote
Thanks Petr! But remember, when I include gluPerspective() with rendering, it doesn't work. This subject need to be studied more.

I'm sure I'll get to it soon. So far, I have been solving collision detection in a Maze program using a two-dimensional array (X/Z) and it works perfectly and quickly, but of course it's not an
OpenGL version.
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