CollisionResult CollisionBody::checkIfCollide(CollisionBody *body2, float deltaT) {
// First of all, don't check collision between collision bodies of the same physical body,
// or of the same group
if (parent == body2->parent || parent->getCollisionGroup() == body2->parent->getCollisionGroup()) {
return CollisionResult(this, body2, 0, Vector3(0, 0, 0));
}
Vector3 body1Vel = this->parent->getVelocity(deltaT * 1000.0f);
Vector3 body2Vel = body2->parent->getVelocity(deltaT * 1000.0f);
Vector3 body1Pos = *getAbsolutePosition();
Vector3 body2Pos = *(body2->getAbsolutePosition());
// Sphere-Sphere collision
if (type == SPHERE && body2->type == SPHERE) {
float distance = pow(body2Pos.x - body1Pos.x, 2) + pow(body2Pos.y - body1Pos.y, 2) + pow(body2Pos.z - body1Pos.z, 2);
if (distance < pow(this->radius + body2->radius, 2)) {
// We have a collision!
float penetration = sqrt(pow(this->radius + body2->radius, 2) - distance);
Vector3 normal = Vector3(body1Pos - body2Pos).normalised();
return CollisionResult(this, body2, penetration, normal);
}
}
// Sphere-Plane collision
if (type == SPHERE && body2->type == PLANE) {
float distancePlaneToSphere = Vector3::dot(*(body2->normal), body1Pos) + body2->radius;
if (distancePlaneToSphere < radius) {
// We have a collision!
float penetration = radius - distancePlaneToSphere;
return CollisionResult(this, body2, penetration, Vector3(*(body2->normal)));
}
}
// Sphere-InvertedCylinder collision
if (type == SPHERE && body2->type == INV_CYLINDER) {
float cylMin = ((body2Pos * *(body2->normal)) - (*(body2->normal) * body2->length)).getLength();
float cylMax = ((body2Pos * *(body2->normal)) + (*(body2->normal) * body2->length)).getLength();
float body1AxisPos = (body1Pos * *(body2->normal)).getLength();
float cylMinX = body2Pos.x - body2->length;
float cylMaxX = body2Pos.x + body2->length;
/* This is the downside of this implementation: if the sphere is only slightly after
* the end of the cylinder, but the lower half is still colliding with it, this
* algorithm won't detect it.
*/
if (body1AxisPos >= cylMin && body1AxisPos <= cylMax) {
Vector3 circunferenceDistance = (body2Pos - body1Pos) * (Vector3(1, 1, 1) - *(body2->normal));
float distance = pow(circunferenceDistance.x, 2) + pow(circunferenceDistance.y, 2) + pow(circunferenceDistance.z, 2);
if (distance > pow(body2->radius - this->radius, 2)) {
// We have a collision!
float penetration = sqrt(distance - pow(body2->radius - this->radius, 2));
Vector3 normal = ((body1Pos - body2Pos) * (Vector3(1, 1, 1) - *(body2->normal))).normalised();
return CollisionResult(this, body2, penetration, normal);
}
}
}
// If there's no collision, or we're trying to detect collision between planes and cylinders, return a no-collision result
return CollisionResult(this, body2, 0, Vector3(0, 0, 0));
}
//**************//
// Game Update //
//**************//
int GSGameProc()
{
Move();
RunAI();
if (GetVerticalBlankCount() % 15 == 0)
SwapBGPalette();
return CollisionResult();
}
