// This one is complicated and gross. Just don't go there...
// TODO: Comment me!
static int
seg2poly(const cpShape *shape1, const cpShape *shape2, cpContact *arr)
{
cpSegmentShape *seg = (cpSegmentShape *)shape1;
cpPolyShape *poly = (cpPolyShape *)shape2;
cpSplittingPlane *planes = poly->tPlanes;
cpFloat segD = cpvdot(seg->tn, seg->ta);
cpFloat minNorm = cpPolyShapeValueOnAxis(poly, seg->tn, segD) - seg->r;
cpFloat minNeg = cpPolyShapeValueOnAxis(poly, cpvneg(seg->tn), -segD) - seg->r;
if(minNeg > 0.0f || minNorm > 0.0f) return 0;
int mini = 0;
cpFloat poly_min = segValueOnAxis(seg, planes->n, planes->d);
if(poly_min > 0.0f) return 0;
for(int i=0; i<poly->numVerts; i++){
cpFloat dist = segValueOnAxis(seg, planes[i].n, planes[i].d);
if(dist > 0.0f){
return 0;
} else if(dist > poly_min){
poly_min = dist;
mini = i;
}
}
int num = 0;
cpVect poly_n = cpvneg(planes[mini].n);
cpVect va = cpvadd(seg->ta, cpvmult(poly_n, seg->r));
cpVect vb = cpvadd(seg->tb, cpvmult(poly_n, seg->r));
if(cpPolyShapeContainsVert(poly, va))
cpContactInit(nextContactPoint(arr, &num), va, poly_n, poly_min, CP_HASH_PAIR(seg->shape.hashid, 0));
if(cpPolyShapeContainsVert(poly, vb))
cpContactInit(nextContactPoint(arr, &num), vb, poly_n, poly_min, CP_HASH_PAIR(seg->shape.hashid, 1));
// Floating point precision problems here.
// This will have to do for now.
// poly_min -= cp_collision_slop; // TODO is this needed anymore?
if(minNorm >= poly_min || minNeg >= poly_min) {
if(minNorm > minNeg)
findPointsBehindSeg(arr, &num, seg, poly, minNorm, 1.0f);
else
findPointsBehindSeg(arr, &num, seg, poly, minNeg, -1.0f);
}
// If no other collision points are found, try colliding endpoints.
if(num == 0){
cpVect poly_a = poly->tVerts[mini];
cpVect poly_b = poly->tVerts[(mini + 1)%poly->numVerts];
if(circle2circleQuery(seg->ta, poly_a, seg->r, 0.0f, arr)) return 1;
if(circle2circleQuery(seg->tb, poly_a, seg->r, 0.0f, arr)) return 1;
if(circle2circleQuery(seg->ta, poly_b, seg->r, 0.0f, arr)) return 1;
if(circle2circleQuery(seg->tb, poly_b, seg->r, 0.0f, arr)) return 1;
}
return num;
}
// This one is complicated and gross. Just don't go there...
// TODO: Comment me!
static int
seg2poly(cpShape *shape1, cpShape *shape2, cpContact **arr)
{
cpSegmentShape *seg = (cpSegmentShape *)shape1;
cpPolyShape *poly = (cpPolyShape *)shape2;
cpPolyShapeAxis *axes = poly->tAxes;
cpFloat segD = cpvdot(seg->tn, seg->ta);
cpFloat minNorm = cpPolyShapeValueOnAxis(poly, seg->tn, segD) - seg->r;
cpFloat minNeg = cpPolyShapeValueOnAxis(poly, cpvneg(seg->tn), -segD) - seg->r;
if(minNeg > 0.0f || minNorm > 0.0f) return 0;
int mini = 0;
cpFloat poly_min = segValueOnAxis(seg, axes->n, axes->d);
if(poly_min > 0.0f) return 0;
for(int i=0; i<poly->numVerts; i++){
cpFloat dist = segValueOnAxis(seg, axes[i].n, axes[i].d);
if(dist > 0.0f){
return 0;
} else if(dist > poly_min){
poly_min = dist;
mini = i;
}
}
int max = 0;
int num = 0;
cpVect poly_n = cpvneg(axes[mini].n);
cpVect va = cpvadd(seg->ta, cpvmult(poly_n, seg->r));
cpVect vb = cpvadd(seg->tb, cpvmult(poly_n, seg->r));
if(cpPolyShapeContainsVert(poly, va))
cpContactInit(addContactPoint(arr, &max, &num), va, poly_n, poly_min, CP_HASH_PAIR(seg, 0));
if(cpPolyShapeContainsVert(poly, vb))
cpContactInit(addContactPoint(arr, &max, &num), vb, poly_n, poly_min, CP_HASH_PAIR(seg, 1));
// Floating point precision problems here.
// This will have to do for now.
poly_min -= cp_collision_slop;
if(minNorm >= poly_min || minNeg >= poly_min) {
if(minNorm > minNeg)
findPointsBehindSeg(arr, &max, &num, seg, poly, minNorm, 1.0f);
else
findPointsBehindSeg(arr, &max, &num, seg, poly, minNeg, -1.0f);
}
return num;
}
// Add contacts for penetrating vertexes.
static inline int
findVerts(cpContact *arr, const cpPolyShape *poly1, const cpPolyShape *poly2, const cpVect n, const cpFloat dist)
{
int num = 0;
for(int i=0; i<poly1->numVerts; i++){
cpVect v = poly1->tVerts[i];
if(cpPolyShapeContainsVert(poly2, v))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly1->shape.hashid, i));
}
for(int i=0; i<poly2->numVerts; i++){
cpVect v = poly2->tVerts[i];
if(cpPolyShapeContainsVert(poly1, v))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly2->shape.hashid, i));
}
return (num ? num : findVertsFallback(arr, poly1, poly2, n, dist));
}
// Add contacts for probably penetrating vertexes.
// This handles the degenerate case where an overlap was detected, but no vertexes fall inside
// the opposing polygon. (like a star of david)
static /*inline*/ int
findVertsFallback(cpContact *arr, const cpPolyShape *poly1, const cpPolyShape *poly2, const cpVect n, const cpFloat dist)
{
int num = 0;
for(int i=0; i<poly1->numVerts; i++){
cpVect v = poly1->tVerts[i];
if(cpPolyShapeContainsVertPartial(poly2, v, cpvneg(n)))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly1->shape.hashid, i));
}
for(int i=0; i<poly2->numVerts; i++){
cpVect v = poly2->tVerts[i];
if(cpPolyShapeContainsVertPartial(poly1, v, n))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly2->shape.hashid, i));
}
return num;
}
// Add contacts for penetrating vertexes.
static inline int
findVerts(cpContact *arr, cpPolyShape *poly1, cpPolyShape *poly2, cpVect n, cpFloat dist)
{
int num = 0;
for(int i=0; i<poly1->numVerts; i++){
cpVect v = poly1->tVerts[i];
if(cpPolyShapeContainsVertPartial(poly2, v, cpvneg(n)))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly1->shape.hashid, i));
}
for(int i=0; i<poly2->numVerts; i++){
cpVect v = poly2->tVerts[i];
if(cpPolyShapeContainsVertPartial(poly1, v, n))
cpContactInit(nextContactPoint(arr, &num), v, n, dist, CP_HASH_PAIR(poly2->shape.hashid, i));
}
// if(!num)
// addContactPoint(arr, &size, &num, cpContactNew(shape1->body->p, n, dist, 0));
return num;
}
// Collide circles to segment shapes.
static int
circle2segment(cpShape *circleShape, cpShape *segmentShape, cpContact **con)
{
cpCircleShape *circ = (cpCircleShape *)circleShape;
cpSegmentShape *seg = (cpSegmentShape *)segmentShape;
// Radius sum
cpFloat rsum = circ->r + seg->r;
// Calculate normal distance from segment.
cpFloat dn = cpvdot(seg->tn, circ->tc) - cpvdot(seg->ta, seg->tn);
cpFloat dist = cpfabs(dn) - rsum;
if(dist > 0.0f) return 0;
// Calculate tangential distance along segment.
cpFloat dt = -cpvcross(seg->tn, circ->tc);
cpFloat dtMin = -cpvcross(seg->tn, seg->ta);
cpFloat dtMax = -cpvcross(seg->tn, seg->tb);
// Decision tree to decide which feature of the segment to collide with.
if(dt < dtMin){
if(dt < (dtMin - rsum)){
return 0;
} else {
return circle2circleQuery(circ->tc, seg->ta, circ->r, seg->r, con);
}
} else {
if(dt < dtMax){
cpVect n = (dn < 0.0f) ? seg->tn : cpvneg(seg->tn);
(*con) = (cpContact *)cpmalloc(sizeof(cpContact));
cpContactInit(
(*con),
cpvadd(circ->tc, cpvmult(n, circ->r + dist*0.5f)),
n,
dist,
0
);
return 1;
} else {
if(dt < (dtMax + rsum)) {
return circle2circleQuery(circ->tc, seg->tb, circ->r, seg->r, con);
} else {
return 0;
}
}
}
return 1;
}
// Identify vertexes that have penetrated the segment.
static inline void
findPointsBehindSeg(cpContact **arr, int *max, int *num, cpSegmentShape *seg, cpPolyShape *poly, cpFloat pDist, cpFloat coef)
{
cpFloat dta = cpvcross(seg->tn, seg->ta);
cpFloat dtb = cpvcross(seg->tn, seg->tb);
cpVect n = cpvmult(seg->tn, coef);
for(int i=0; i<poly->numVerts; i++){
cpVect v = poly->tVerts[i];
if(cpvdot(v, n) < cpvdot(seg->tn, seg->ta)*coef + seg->r){
cpFloat dt = cpvcross(seg->tn, v);
if(dta >= dt && dt >= dtb){
cpContactInit(addContactPoint(arr, max, num), v, n, pDist, CP_HASH_PAIR(poly->shape.hashid, i));
}
}
}
}
// This one is less gross, but still gross.
// TODO: Comment me!
static int
circle2poly(cpShape *shape1, cpShape *shape2, cpContact **con)
{
cpCircleShape *circ = (cpCircleShape *)shape1;
cpPolyShape *poly = (cpPolyShape *)shape2;
cpPolyShapeAxis *axes = poly->tAxes;
int mini = 0;
cpFloat min = cpvdot(axes->n, circ->tc) - axes->d - circ->r;
for(int i=0; i<poly->numVerts; i++){
cpFloat dist = cpvdot(axes[i].n, circ->tc) - axes[i].d - circ->r;
if(dist > 0.0f){
return 0;
} else if(dist > min) {
min = dist;
mini = i;
}
}
cpVect n = axes[mini].n;
cpVect a = poly->tVerts[mini];
cpVect b = poly->tVerts[(mini + 1)%poly->numVerts];
cpFloat dta = cpvcross(n, a);
cpFloat dtb = cpvcross(n, b);
cpFloat dt = cpvcross(n, circ->tc);
if(dt < dtb){
return circle2circleQuery(circ->tc, b, circ->r, 0.0f, con);
} else if(dt < dta) {
(*con) = (cpContact *)cpmalloc(sizeof(cpContact));
cpContactInit(
(*con),
cpvsub(circ->tc, cpvmult(n, circ->r + min/2.0f)),
cpvneg(n),
min,
0
);
return 1;
} else {
return circle2circleQuery(circ->tc, a, circ->r, 0.0f, con);
}
}
// This one is less gross, but still gross.
// TODO: Comment me!
static int
circle2poly(const cpShape *shape1, const cpShape *shape2, cpContact *con)
{
cpCircleShape *circ = (cpCircleShape *)shape1;
cpPolyShape *poly = (cpPolyShape *)shape2;
cpSplittingPlane *planes = poly->tPlanes;
int mini = 0;
cpFloat min = cpSplittingPlaneCompare(planes[0], circ->tc) - circ->r;
for(int i=0; i<poly->numVerts; i++){
cpFloat dist = cpSplittingPlaneCompare(planes[i], circ->tc) - circ->r;
if(dist > 0.0f){
return 0;
} else if(dist > min) {
min = dist;
mini = i;
}
}
cpVect n = planes[mini].n;
cpVect a = poly->tVerts[mini];
cpVect b = poly->tVerts[(mini + 1)%poly->numVerts];
cpFloat dta = cpvcross(n, a);
cpFloat dtb = cpvcross(n, b);
cpFloat dt = cpvcross(n, circ->tc);
if(dt < dtb){
return circle2circleQuery(circ->tc, b, circ->r, 0.0f, con);
} else if(dt < dta) {
cpContactInit(
con,
cpvsub(circ->tc, cpvmult(n, circ->r + min/2.0f)),
cpvneg(n),
min,
0
);
return 1;
} else {
return circle2circleQuery(circ->tc, a, circ->r, 0.0f, con);
}
}
// Add contact points for circle to circle collisions.
// Used by several collision tests.
static int
circle2circleQuery(const cpVect p1, const cpVect p2, const cpFloat r1, const cpFloat r2, cpContact *con)
{
cpFloat mindist = r1 + r2;
cpVect delta = cpvsub(p2, p1);
cpFloat distsq = cpvlengthsq(delta);
if(distsq >= mindist*mindist) return 0;
cpFloat dist = cpfsqrt(distsq);
// Allocate and initialize the contact.
cpContactInit(
con,
cpvadd(p1, cpvmult(delta, 0.5f + (r1 - 0.5f*mindist)/(dist ? dist : INFINITY))),
(dist ? cpvmult(delta, 1.0f/dist) : cpv(1.0f, 0.0f)),
dist - mindist,
0
);
return 1;
}
// Add contact points for circle to circle collisions.
// Used by several collision tests.
static int
circle2circleQuery(cpVect p1, cpVect p2, cpFloat r1, cpFloat r2, cpContact *con)
{
cpFloat mindist = r1 + r2;
cpVect delta = cpvsub(p2, p1);
cpFloat distsq = cpvlengthsq(delta);
if(distsq >= mindist*mindist) return 0;
cpFloat dist = cpfsqrt(distsq);
// To avoid singularities, do nothing in the case of dist = 0.
cpFloat non_zero_dist = (dist ? dist : INFINITY);
// Allocate and initialize the contact.
cpContactInit(
con,
cpvadd(p1, cpvmult(delta, 0.5f + (r1 - 0.5f*mindist)/non_zero_dist)),
cpvmult(delta, 1.0f/non_zero_dist),
dist - mindist,
0
);
return 1;
}
