replaced tri_inside with tri_find_z and it works!

This commit is contained in:
Trammell hudson 2017-10-07 15:05:02 -04:00
parent 8e82fb44c6
commit 72634d0f11
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@ -41,7 +41,6 @@ struct _tri_t
{ {
v3_t p[3]; // camera space v3_t p[3]; // camera space
v3_t normal; // camera space v3_t normal; // camera space
v3_t p_xyz[3]; // original xyz space
v3_t normal_xyz; // original xyz space v3_t normal_xyz; // original xyz space
float min[3]; // camera space float min[3]; // camera space
float max[3]; // camera space float max[3]; // camera space
@ -205,77 +204,6 @@ if(0) fprintf(stderr, "collision: %.0f,%.0f,%.0f->%.0f,%.0f,%.0f %.0f,%.0f,%.0f-
int
tri_inside(
const tri_t * const t,
const v3_t * const p,
v3_t * const bary
)
{
#if 1
const float p0x = t->p[0].p[0];
const float p0y = t->p[0].p[1];
const float p1x = t->p[1].p[0];
const float p1y = t->p[1].p[1];
const float p2x = t->p[2].p[0];
const float p2y = t->p[2].p[1];
const float px = p->p[0];
const float py = p->p[1];
// compute the barycentric coordinates of p in triangle t
const float a = (p1y - p2y)*(p0x - p2x) + (p2x - p1x)*(p0y - p2y);
//fprintf(stderr, "a=%f\n", a);
if (a < EPS)
{
// triangle is too small or has negative area
return 0;
}
const float alpha = ((p1y - p2y)*(px - p2x) + (p2x - p1x)*(py - p2y));
const float beta = ((p2y - p0y)*(px - p2x) + (p0x - p2x)*(py - p2y));
const float gamma = a - alpha - beta;
if (bary)
*bary = (v3_t) {{ alpha, beta, gamma }};
if(0) fprintf(stderr, "a=%f b=%f g=%f\n", alpha, beta, gamma);
if (alpha < 0 || beta < 0 || gamma < 0)
return 0;
// inside!
if(0) fprintf(stderr, "%p: %f,%f inside %f,%f %f,%f %f,%f\n",
t,
px, py,
p0x, p0y,
p1x, p1y,
p2x, p2y
);
#else
const v3_t v1 = v3_sub(t->p[2], t->p[0]);
const v3_t v2 = v3_sub(t->p[1], t->p[0]);
const v3_t v = v3_sub(*p, t->p[0]);
const float d = det(v1,v2);
const float a = (det(*p,v2) - det(t->p[0], v2)) / +d;
const float b = (det(*p,v1) - det(t->p[0], v1)) / -d;
//const float a = +det(v,v2) / d;
//const float b = -det(v,v1) / d;
fprintf(stderr, "a=%f b=%f d=%f\n", a, b, d);
if (a < 0 || b < 0)
return 0;
if (a + b > 1)
return 0;
#endif
return 1;
}
tri_t * tri_t *
tri_new( tri_new(
@ -287,10 +215,7 @@ tri_new(
if (!t) if (!t)
return NULL; return NULL;
for(int i = 0 ; i < 3 ; i++) for(int i = 0 ; i < 3 ; i++)
{
t->p[i] = p_cam[i]; t->p[i] = p_cam[i];
t->p_xyz[i] = p_xyz[i];
}
// precompute the normals // precompute the normals
t->normal = v3_norm(v3_cross( t->normal = v3_norm(v3_cross(
@ -298,8 +223,8 @@ tri_new(
v3_sub(t->p[2], t->p[1]) v3_sub(t->p[2], t->p[1])
)); ));
t->normal_xyz = v3_norm(v3_cross( t->normal_xyz = v3_norm(v3_cross(
v3_sub(t->p_xyz[1], t->p_xyz[0]), v3_sub(p_xyz[1], p_xyz[0]),
v3_sub(t->p_xyz[2], t->p_xyz[1]) v3_sub(p_xyz[2], p_xyz[1])
)); ));
@ -461,40 +386,6 @@ tri_coplanar(
} }
} }
/** Find the Z point of a given xy point along the segment from p0 to p1.
*
* Returns -1 if there is no known Z point.
*/
float
find_z(
const v3_t * const p0,
const v3_t * const p1,
const float x,
const float y
)
{
const float dx = p1->p[0] - p0->p[0];
const float dy = p1->p[1] - p0->p[1];
const float dz = p1->p[2] - p0->p[2];
// find the z value of the intersection point
// on the segment. we don't care about the triangle
float ratio = 0;
if (dx != 0)
{
ratio = (x - p0->p[0]) / dx;
} else
if (dy != 0)
{
ratio = (y - p0->p[1]) / dy;
} else {
fprintf(stderr, "uh, dx and dy both zero?\n");
return -1;
}
return p0->p[2] + dz * ratio;
}
/* /*
* Find the Z point of an XY coordinate in a triangle. * Find the Z point of an XY coordinate in a triangle.
@ -505,10 +396,11 @@ find_z(
* p = a * t1 + b * t2 * p = a * t1 + b * t2
* which is two equations with two unknowns * which is two equations with two unknowns
*/ */
float int
tri_find_z( tri_find_z(
const tri_t * const t, const tri_t * const t,
const v3_t * const p const v3_t * const p,
float * const zout
) )
{ {
const float t1x = t->p[1].p[0] - t->p[0].p[0]; const float t1x = t->p[1].p[0] - t->p[0].p[0];
@ -525,7 +417,10 @@ tri_find_z(
const float z = t->p[0].p[2] + a * t1z + b * t2z; const float z = t->p[0].p[2] + a * t1z + b * t2z;
return z; if (zout)
*zout = z;
return 0 <= a && 0 <= b && a + b <= 1;
} }
@ -615,20 +510,19 @@ fprintf(stderr, "%d: processing segment ", recursive++); seg_print(s);
continue; continue;
#endif #endif
v3_t bary[2] = {}; float z0, z1;
int inside0 = tri_inside(t, &s->p[0], &bary[0]); int inside0 = tri_find_z(t, &s->p[0], &z0);
int inside1 = tri_inside(t, &s->p[1], &bary[1]); int inside1 = tri_find_z(t, &s->p[1], &z1);
// if both are inside and the triangle is behind // if both are inside but the segment is infront of the
// this segment, then we discard this segment // triangle, then we retain the segment.
// otherwies we discard the segment
if (inside0 && inside1) if (inside0 && inside1)
{ {
float p0_tri_z = tri_find_z(t, &s->p[0]); if (s->p[0].p[2] <= z0)
if (s->p[0].p[2] <= p0_tri_z) continue;
if (s->p[1].p[2] <= z1)
continue; continue;
fprintf(stderr, "z=%.3f ", p0_tri_z);
seg_print(s);
tri_print(t);
//svg_line("#0000FF", s->p[0].p, s->p[1].p, 0); //svg_line("#0000FF", s->p[0].p, s->p[1].p, 0);
//svg_line("#00FF00", t->p[0].p, t->p[1].p, 0); //svg_line("#00FF00", t->p[0].p, t->p[1].p, 0);
@ -638,8 +532,6 @@ if(0) {
fprintf(stderr, "BOTH INSIDE\n"); fprintf(stderr, "BOTH INSIDE\n");
tri_print(t); tri_print(t);
seg_print(s); seg_print(s);
fprintf(stderr, "bary0 %f,%f,%f\n", bary[0].p[0], bary[0].p[1], bary[0].p[2]);
fprintf(stderr, "bary1 %f,%f,%f\n", bary[1].p[0], bary[1].p[1], bary[1].p[2]);
} }
//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10); //svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
//svg_line("#0000FF", t->p[0].p, t->p[1].p, 2); //svg_line("#0000FF", t->p[0].p, t->p[1].p, 2);
@ -708,25 +600,7 @@ svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
if (intersections == 2) if (intersections == 2)
{ {
// if the segment intersection is closer than the triangle, // figure out how far it is to each of the intersections
// then we do nothing. degenerate cases are not handled
if (is[0].p[2] <= it[0].p[2]
|| is[1].p[2] <= it[1].p[2])
{
/*
fprintf(stderr, "ignoring collision since z %f < %f || %f < %f\n",
is[0].p[2], it[0].p[2],
is[1].p[2], it[1].p[2]);
*/
continue;
}
// segment is behind the triangle,
// we have to create a new segment
// and shorten the existing segment
// find the two intersections that we have
// update the src field
const float d00 = v3_len(&s->p[0], &is[0]); const float d00 = v3_len(&s->p[0], &is[0]);
const float d01 = v3_len(&s->p[0], &is[1]); const float d01 = v3_len(&s->p[0], &is[1]);
const float d10 = v3_len(&s->p[1], &is[0]); const float d10 = v3_len(&s->p[1], &is[0]);
@ -747,6 +621,23 @@ fprintf(stderr, "ignoring collision since z %f < %f || %f < %f\n",
return; return;
} }
// if the segment intersection is closer than the triangle,
// then we do nothing. degenerate cases are not handled
if (d00 <= d01
&& is[0].p[2] <= it[0].p[2]
&& is[1].p[2] <= it[1].p[2])
continue;
if (d00 > d01
&& is[1].p[2] <= it[0].p[2]
&& is[0].p[2] <= it[1].p[2])
continue;
// segment is behind the triangle,
// we have to create a new segment
// and shorten the existing segment
// find the two intersections that we have
// update the src field
// we need to create a new segment // we need to create a new segment
seg_t * news; seg_t * news;
if (d00 < d01) if (d00 < d01)
@ -785,8 +676,12 @@ seg_print(news);
// is closer than the triangle intercept, then no problem. // is closer than the triangle intercept, then no problem.
// we do not bother with degenerate cases of intersecting // we do not bother with degenerate cases of intersecting
// triangles // triangles
if (is[0].p[2] <= it[0].p[2]) if (is[0].p[2] <= it[0].p[2]
&& is[1].p[2] <= it[0].p[2])
{
//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
continue; continue;
}
/* /*
// due to floating point issues, one of these might // due to floating point issues, one of these might
@ -827,6 +722,7 @@ seg_print(news);
news->src[1] = s->src[1]; news->src[1] = s->src[1];
s->p[0] = is[0]; s->p[0] = is[0];
tri_seg_intersect(zlist->next, news, slist_visible); tri_seg_intersect(zlist->next, news, slist_visible);
//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
//fprintf(stderr, "%d -----\n", --recursive); //fprintf(stderr, "%d -----\n", --recursive);
// continue splitting our current segment // continue splitting our current segment