for (i = 0; i < NUM_SPRITES; i++)
{
if (i != sprite)
{
//top collisions
RECT1.top = g_Sprite[sprite].fPosY;
RECT1.left = g_Sprite[sprite].fPosX;
RECT1.bottom = g_Sprite[sprite].fPosY + SPRITE_DIAMETER;
RECT1.right = g_Sprite[sprite].fPosX + SPRITE_DIAMETER;
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.left = g_Sprite.fPosX;
RECT2.bottom = g_Sprite.fPosY - SPRITE_DIAMETER + g_Sprite.fVelX;
RECT2.right = g_Sprite.fPosX + SPRITE_DIAMETER;
collision = IntersectRects(RECT1, RECT2);
if (collision == true)
{
hold = (-g_Sprite.fVelY + g_Sprite[sprite].fVelY)/2;
g_Sprite.fVelY = hold;
g_Sprite[sprite].fVelY = -hold;
}
}
}
for (i = 0; i < NUM_SPRITES; i++)
{
if (i != sprite)
{
//bottom collisions
RECT1.top = g_Sprite[sprite].fPosY;
RECT1.left = g_Sprite[sprite].fPosX;
RECT1.bottom = g_Sprite[sprite].fPosY + SPRITE_DIAMETER;
RECT1.right = g_Sprite[sprite].fPosX + SPRITE_DIAMETER;
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.left = g_Sprite.fPosX;
RECT2.bottom = g_Sprite.fPosY + SPRITE_DIAMETER + g_Sprite.fVelX;
RECT2.right = g_Sprite.fPosX + SPRITE_DIAMETER;
collision = IntersectRects(RECT1, RECT2);
if (collision == true)
{
hold = (g_Sprite.fVelY + -g_Sprite[sprite].fVelY)/2;
g_Sprite.fVelY = -hold;
g_Sprite[sprite].fVelY = hold;
}
}
}
for (i = 0; i < NUM_SPRITES; i++)
{
if (i != sprite)
{
//left collisions
RECT1.top = g_Sprite[sprite].fPosY;
RECT1.left = g_Sprite[sprite].fPosX;
RECT1.bottom = g_Sprite[sprite].fPosY + SPRITE_DIAMETER;
RECT1.right = g_Sprite[sprite].fPosX + SPRITE_DIAMETER;
RECT2.top = g_Sprite.fPosY;
RECT2.left = g_Sprite.fPosX + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY + SPRITE_DIAMETER;
RECT2.right = g_Sprite.fPosX + SPRITE_DIAMETER + g_Sprite.fVelX;
collision = IntersectRects(RECT1, RECT2);
if (collision == true)
{
hold = (-g_Sprite.fVelX + g_Sprite[sprite].fVelX)/2;
g_Sprite.fVelX = hold;
g_Sprite[sprite].fVelX = -hold;
}
}
}
for (i = 0; i < NUM_SPRITES; i++)
{
if (i != sprite)
{
//right collisions
RECT1.top = g_Sprite[sprite].fPosY;
RECT1.left = g_Sprite[sprite].fPosX;
RECT1.bottom = g_Sprite[sprite].fPosY + SPRITE_DIAMETER;
RECT1.right = g_Sprite[sprite].fPosX + SPRITE_DIAMETER;
RECT2.top = g_Sprite.fPosY;
RECT2.left = g_Sprite.fPosX + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY + SPRITE_DIAMETER;
RECT2.right = g_Sprite.fPosX + SPRITE_DIAMETER + g_Sprite.fVelX;
collision = IntersectRects(RECT1, RECT2);
if (collision == true)
{
hold = (g_Sprite.fVelX + -g_Sprite[sprite].fVelX)/2;
g_Sprite.fVelX = -hold;
g_Sprite[sprite].fVelX = hold;
}
}
}
2d collision problems
Author
I'm doing some simple 2d collision detection and everything worked fine, I think. but when I threw in some very simple physics some collisions didn't work.
for some reason about half the time on top or bottom collisions the sprite passes through another. but the left/right collisions work fine. does anyone know what could be wrong wrong?
p.s. if you need to see anything else ask and I'll post it.
Author
that method seems to work fine. but here you go just in case:
bool IntersectRects(RECT rect1, RECT rect2){ if (rect1.right > rect2.left) { if (rect1.left < rect2.right) { if (rect1.top < rect2.bottom) { if (rect1.bottom > rect2.top) { return true; } } } } return false;}
That's a one-way collision comparison - that is, you'd have to call IntersectRects(r1, r2) AND IntersectRects(r2, r1) to get a valid collision detection. You can write a rectangular collision detection function that goes both ways without too much trouble, though.
No, that rectangle collision detection appears to be correct.
On the other hand:
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY - SPRITE_DIAMETER + g_Sprite.fVelX;
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY + SPRITE_DIAMETER + g_Sprite.fVelX;
Unless there's some sort of explanation for why x velocities are being added to y positions, I think this could be the problem.
On the other hand:
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY - SPRITE_DIAMETER + g_Sprite.fVelX;
RECT2.top = g_Sprite.fPosY + g_Sprite.fVelX;
RECT2.bottom = g_Sprite.fPosY + SPRITE_DIAMETER + g_Sprite.fVelX;
Unless there's some sort of explanation for why x velocities are being added to y positions, I think this could be the problem.
Author
that may be the problem, I thought I fixed that :(. well I'm not at a computer with a compiler right now so I can't do anything. but if it works then I'll say, if not I'll say anyway.
This topic is closed to new replies.
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