Okay, I''m almost there now. The collisions are happening, but there''s a small problem, they aren''t accurate completely. They are accurate for 3/4 of the collision shape, but the upper left corner of the collision seems to be comletely innacurate.
Below is a picture of what I mean. The white boxes are the two collision boxes for the player ship, the red lines indicate where the collision boundaries seem to be...
So, here''s the new code......(there''s quite a bit of it)
bool ACollision::DoesPlayerCollide(Actor* B){ if (B->CollisionBox==NULL) return false; if (B->CollisionBox->Owner==NULL) return false; if (B->CollisionBox->colType==CT_NULL) return false; if (Plyr->bDying || Plyr->newLifeDelay>0.0f) return false; float minX1=Plyr->xpos; float maxX1=Plyr->xpos+Plyr->w; float minY1=Plyr->ypos; float maxY1=Plyr->ypos+Plyr->h; float minX2=B->getXPos(); float maxX2=B->getXPos()+B->getWidth(); float minY2=B->getYPos(); float maxY2=B->getYPos()+B->getHeight(); if (maxY1<minY2) return false; if (minY1>maxY2) return false; if (maxX1<minX2) return false; if (minX1>maxX2) return false; else { return AdvancedCheckPlayer(Plyr->CollisionBox, B->CollisionBox); } return false;}bool ACollision::AdvancedCheckPlayer(ACollision* A, ACollision* B){ // do more advanced polygonal checks for collisions // recursion is used to check for multiple polygons per object // if (colA collides colB) // return true // else // if (colA->next!=NULL) // AdvancedCheck(colA->next, colB) // else // if (colB->next!=NULL) // advancedCheck(colA, colB->next) bool bCollided=false; if (A->colType==CT_Box && B->colType==CT_Box) { bCollided=true; float minX1=Plyr->xpos+A->xoffset; float maxX1=Plyr->xpos+A->xoffset+A->w; float minY1=Plyr->ypos+A->yoffset; float maxY1=Plyr->ypos+A->yoffset+A->h; float minX2=B->Owner->getXPos()+B->xoffset; float maxX2=B->Owner->getXPos()+B->xoffset+B->w; float minY2=B->Owner->getYPos()+B->yoffset; float maxY2=B->Owner->getYPos()+B->yoffset+B->h; if (maxY1<minY2) bCollided=false; if (minY1>maxY2) bCollided=false; if (maxX1<minX2) bCollided=false; if (minX1>maxX2) bCollided=false; } else if (A->colType==CT_Circle && B->colType==CT_Box) { // get point for circle A and circle A centre and do point checks // get centre point and check bCollided=false; A->PreRotate(); // get directional radial point and do collision point check float x,y,xs,ys,l; x=( B->Owner->getXPos()+B->xoffset+(B->w*0.5f) )-A->centreX; y=( B->Owner->getYPos()+B->yoffset+(B->h*0.5f) )-A->centreY; l=dist(x,y); xs=x/l; ys=x/l; x=radius*xs; y=radius*ys; if (LineToBoxIntersectPlayer(A->centreX, A->centreY, A->centreX+x, A->centreY+y, B)) return true; } else if (A->colType==CT_Box && B->colType==CT_Circle) { // do point checks by reversing B and A bCollided=false; B->PreRotate(); // get directional radial point and do line->box collision check float x,y,xs,ys,l; x=( Plyr->xpos+A->xoffset+(A->w*0.5f) )-B->centreX; y=( Plyr->ypos+A->yoffset+(A->h*0.5f) )-B->centreY; l=dist(x,y); xs=x/l; ys=x/l; x=radius*xs; y=radius*ys; if (LineToBoxIntersectPlayer(B->centreX, B->centreY, B->centreX+x, B->centreY+y, A)) return true; } else if (A->colType==CT_Circle && B->colType==CT_Circle) { bCollided=false; A->PreRotate(); B->PreRotate(); // get directional radial point and do collision point check float x,y,l; x=A->centreX-B->centreX; y=A->centreY-B->centreY; l=dist(x,y); if (l<0.0f) l*=-1; if (l<(A->radius+B->radius)) return true; } if (bCollided) return true; else { if (A->next!=NULL) { bCollided=AdvancedCheckPlayer(A->next, B); if (bCollided) return true; } else if (B->next!=NULL) { bCollided=AdvancedCheckPlayer(Plyr->CollisionBox, B->next); if (bCollided) return true; } } return bCollided;}
That''s the two main checking functions, that handle the recursion and general box checks. Here''s the maths side of things:
void ACollision::PreRotate(){ // rotate the centre point around the owners rotation origins if (Owner!=NULL) { baseCentreX=Owner->getXPos()+xoffset+(w*0.5f); baseCentreY=Owner->getYPos()+yoffset+(h*0.5f); if (Owner->drawType==DT_Rotating) { float r = deg2rad(Owner->rotation); centreX=cosf(r) * (baseCentreX-Owner->rotX) - sinf(r) * (baseCentreY-Owner->rotY) + Owner->rotX; centreY=sinf(r) * (baseCentreX-Owner->rotX) + cosf(r) * (baseCentreY-Owner->rotY) + Owner->rotY; } else { centreX=baseCentreX; centreY=baseCentreY; } } else { centreX=Plyr->xpos+xoffset+(w*0.5f); centreY=Plyr->ypos+yoffset+(h*0.5f); }}bool ACollision::LineIntersect(float ax, float ay, float bx, float by, float cx, float cy, float dx, float dy){ // line intersection test float s = (cy - dy) * (bx - ax) - (cx - dx) * (by - ay); if (s == 0) { // Lines don''t intersect return false; } s = ((cy - ay) * (bx - ax) - (cx - ax) * (by - ay)) / s; if (s < 0 || s > 1) { // Lines don''t intersect return false; } // tbd: use this intersection point code //p0 = c0 + s * (d0 - c0) //p1 = c1 + s * (d1 - c1) return true;}bool ACollision::LineToBoxIntersectPlayer(float ax, float ay, float bx, float by, ACollision* box){ // check all four box sides vs the intersector line float cx,cy,dx,dy; // left side cx=Plyr->xpos+box->xoffset; cy=Plyr->ypos+box->yoffset; dx=Plyr->xpos+box->xoffset; dy=Plyr->ypos+box->yoffset+box->h; if (LineIntersect(ax,ay,bx,by,cx,cy,dx,dy)) return true; // right side cx=Plyr->xpos+box->xoffset+box->w; cy=Plyr->ypos+box->yoffset; dx=Plyr->xpos+box->xoffset+box->w; dy=Plyr->ypos+box->yoffset+box->h; if (LineIntersect(ax,ay,bx,by,cx,cy,dx,dy)) return true; // top side cx=Plyr->xpos+box->xoffset; cy=Plyr->ypos+box->yoffset; dx=Plyr->xpos+box->xoffset+box->w; dy=Plyr->ypos+box->yoffset; if (LineIntersect(ax,ay,bx,by,cx,cy,dx,dy)) return true; // bottom side cx=Plyr->xpos+box->xoffset; cy=Plyr->ypos+box->yoffset+box->h; dx=Plyr->xpos+box->xoffset+box->w; dy=Plyr->ypos+box->yoffset+box->h; if (LineIntersect(ax,ay,bx,by,cx,cy,dx,dy)) return true; return false;}
So each object has a pointer to a collision object, and that collision object uses a linked list (via the ''next'' pointer) to the next one in the collisions list. This allows me to add as many layers of collision detail as I feel necessary. So it recurses through the collision shapes, doing the checks againt one another, but somehow, in the situation where a circular collision is striking the player (box collisions) the collision shapes go funny like in the diagram above. Box vs Box collisions work perfecty as do circle vs circle collisions. but when they mix n match it goes funny
