2D Breakout collision problem

CloudNine · 2003-08-19T10:21:32

Yo, Since I consider 2d collision detection one of my weak spots, I decided to code a Breakout game but I''ve run into problems. I''ve been following this tutorial, for a simple rectangle overlap collision (1st bit of code) I''ve intergrated it with my code successfully. However, the ball''s current behaviour is that it bounces off the bat correctly, but about 1.5 units (roughly the height of the bat) above the bat. After seeing several other examples, I was wondering, should I take into account the ball speed? Here''s some useful code. Note that I check for collision after I update the ball, and that both are called every frame. bool BatBallCollide(BBALL *ball,BBAT* bat) { float left1,left2; float right1,right2; float top1,top2; float bottom1,bottom2; left1=ball->GetX(); right1=left1+ball->GetWidth(); top1=ball->GetY(); bottom1=top1+ball->GetHeight(); left2=bat->GetX(); right2=left2+bat->GetWidth(); top2=bat->GetY(); bottom2=top2+bat->GetHeight(); if (bottom1<top2) return false; if (top1>bottom2) return false; if (right1<left2) return false; if (left1>right2) return false; return true; } And my current updating/rendering function: void RenderScene() { ball.Update(); bat.Update(); if (BatBallCollide(&ball,&bat)) { ball.SetYDir(-ball.GetYDir()); } glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glLoadIdentity(); DrawBlocks(); ball.Draw(); bat.Draw(); } Cheers for any help CloudNine

Math and Physics Programming

Started by CloudNine August 16, 2003 11:48 AM

9 comments, last by CloudNine 20 years, 8 months ago

ZitherMan

139

August 19, 2003 10:21 AM

I made my 2d-colissionsystem as such:

Store the "radii''s" ie, the length from the center of the object to the left/right edge and from the center of the object to the top/bottom. Each frame you test the two objects radii''s against eachother, if BOTH the x and the y radii''s overlap, there is a colission. This is only for bounding boxes though but that seems to be what you want? You will get pixel-perfect colissions with this unless the speed is so great the ball will "move through" the bat.

This also eliminates this error:

      |-------|      |       |  |----------------|  |   |       |    |  |   |       |    |  |   |       |    |  |----------------|      |       |      |-------|

Ok these objects got no vertices inside eachother, some systems would not recognize a colission in this.

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2D Breakout collision problem

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2D Breakout collision problem

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