replaced tri_inside with tri_find_z and it works!
This commit is contained in:
Trammell hudson
parent
8e82fb44c6
commit
72634d0f11
188
hiddenwire.c
188
hiddenwire.c
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@ -41,7 +41,6 @@ struct _tri_t
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{
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v3_t p[3]; // camera space
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v3_t normal; // camera space
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v3_t p_xyz[3]; // original xyz space
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v3_t normal_xyz; // original xyz space
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float min[3]; // camera space
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float max[3]; // camera space
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@ -205,77 +204,6 @@ if(0) fprintf(stderr, "collision: %.0f,%.0f,%.0f->%.0f,%.0f,%.0f %.0f,%.0f,%.0f-
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int
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tri_inside(
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const tri_t * const t,
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const v3_t * const p,
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v3_t * const bary
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)
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{
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#if 1
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const float p0x = t->p[0].p[0];
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const float p0y = t->p[0].p[1];
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const float p1x = t->p[1].p[0];
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const float p1y = t->p[1].p[1];
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const float p2x = t->p[2].p[0];
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const float p2y = t->p[2].p[1];
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const float px = p->p[0];
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const float py = p->p[1];
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// compute the barycentric coordinates of p in triangle t
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const float a = (p1y - p2y)*(p0x - p2x) + (p2x - p1x)*(p0y - p2y);
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//fprintf(stderr, "a=%f\n", a);
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if (a < EPS)
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{
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// triangle is too small or has negative area
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return 0;
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}
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const float alpha = ((p1y - p2y)*(px - p2x) + (p2x - p1x)*(py - p2y));
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const float beta = ((p2y - p0y)*(px - p2x) + (p0x - p2x)*(py - p2y));
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const float gamma = a - alpha - beta;
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if (bary)
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*bary = (v3_t) {{ alpha, beta, gamma }};
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if(0) fprintf(stderr, "a=%f b=%f g=%f\n", alpha, beta, gamma);
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if (alpha < 0 || beta < 0 || gamma < 0)
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return 0;
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// inside!
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if(0) fprintf(stderr, "%p: %f,%f inside %f,%f %f,%f %f,%f\n",
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t,
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px, py,
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p0x, p0y,
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p1x, p1y,
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p2x, p2y
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);
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#else
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const v3_t v1 = v3_sub(t->p[2], t->p[0]);
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const v3_t v2 = v3_sub(t->p[1], t->p[0]);
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const v3_t v = v3_sub(*p, t->p[0]);
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const float d = det(v1,v2);
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const float a = (det(*p,v2) - det(t->p[0], v2)) / +d;
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const float b = (det(*p,v1) - det(t->p[0], v1)) / -d;
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//const float a = +det(v,v2) / d;
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//const float b = -det(v,v1) / d;
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fprintf(stderr, "a=%f b=%f d=%f\n", a, b, d);
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if (a < 0 || b < 0)
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return 0;
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if (a + b > 1)
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return 0;
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#endif
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return 1;
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}
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tri_t *
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tri_new(
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@ -287,10 +215,7 @@ tri_new(
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if (!t)
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return NULL;
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for(int i = 0 ; i < 3 ; i++)
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{
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t->p[i] = p_cam[i];
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t->p_xyz[i] = p_xyz[i];
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}
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// precompute the normals
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t->normal = v3_norm(v3_cross(
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@ -298,8 +223,8 @@ tri_new(
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v3_sub(t->p[2], t->p[1])
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));
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t->normal_xyz = v3_norm(v3_cross(
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v3_sub(t->p_xyz[1], t->p_xyz[0]),
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v3_sub(t->p_xyz[2], t->p_xyz[1])
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v3_sub(p_xyz[1], p_xyz[0]),
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v3_sub(p_xyz[2], p_xyz[1])
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));
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@ -461,40 +386,6 @@ tri_coplanar(
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}
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}
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/** Find the Z point of a given xy point along the segment from p0 to p1.
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*
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* Returns -1 if there is no known Z point.
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*/
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float
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find_z(
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const v3_t * const p0,
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const v3_t * const p1,
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const float x,
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const float y
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)
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{
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const float dx = p1->p[0] - p0->p[0];
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const float dy = p1->p[1] - p0->p[1];
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const float dz = p1->p[2] - p0->p[2];
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// find the z value of the intersection point
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// on the segment. we don't care about the triangle
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float ratio = 0;
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if (dx != 0)
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{
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ratio = (x - p0->p[0]) / dx;
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} else
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if (dy != 0)
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{
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ratio = (y - p0->p[1]) / dy;
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} else {
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fprintf(stderr, "uh, dx and dy both zero?\n");
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return -1;
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}
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return p0->p[2] + dz * ratio;
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}
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/*
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* Find the Z point of an XY coordinate in a triangle.
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@ -505,10 +396,11 @@ find_z(
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* p = a * t1 + b * t2
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* which is two equations with two unknowns
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*/
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float
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int
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tri_find_z(
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const tri_t * const t,
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const v3_t * const p
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const v3_t * const p,
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float * const zout
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)
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{
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const float t1x = t->p[1].p[0] - t->p[0].p[0];
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@ -525,7 +417,10 @@ tri_find_z(
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const float z = t->p[0].p[2] + a * t1z + b * t2z;
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return z;
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if (zout)
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*zout = z;
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return 0 <= a && 0 <= b && a + b <= 1;
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}
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@ -615,20 +510,19 @@ fprintf(stderr, "%d: processing segment ", recursive++); seg_print(s);
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continue;
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#endif
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v3_t bary[2] = {};
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int inside0 = tri_inside(t, &s->p[0], &bary[0]);
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int inside1 = tri_inside(t, &s->p[1], &bary[1]);
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float z0, z1;
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int inside0 = tri_find_z(t, &s->p[0], &z0);
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int inside1 = tri_find_z(t, &s->p[1], &z1);
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// if both are inside and the triangle is behind
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// this segment, then we discard this segment
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// if both are inside but the segment is infront of the
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// triangle, then we retain the segment.
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// otherwies we discard the segment
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if (inside0 && inside1)
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{
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float p0_tri_z = tri_find_z(t, &s->p[0]);
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if (s->p[0].p[2] <= p0_tri_z)
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if (s->p[0].p[2] <= z0)
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continue;
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if (s->p[1].p[2] <= z1)
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continue;
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fprintf(stderr, "z=%.3f ", p0_tri_z);
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seg_print(s);
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tri_print(t);
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//svg_line("#0000FF", s->p[0].p, s->p[1].p, 0);
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//svg_line("#00FF00", t->p[0].p, t->p[1].p, 0);
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@ -638,8 +532,6 @@ if(0) {
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fprintf(stderr, "BOTH INSIDE\n");
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tri_print(t);
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seg_print(s);
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fprintf(stderr, "bary0 %f,%f,%f\n", bary[0].p[0], bary[0].p[1], bary[0].p[2]);
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fprintf(stderr, "bary1 %f,%f,%f\n", bary[1].p[0], bary[1].p[1], bary[1].p[2]);
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}
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//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
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//svg_line("#0000FF", t->p[0].p, t->p[1].p, 2);
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@ -708,25 +600,7 @@ svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
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if (intersections == 2)
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{
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// if the segment intersection is closer than the triangle,
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// then we do nothing. degenerate cases are not handled
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if (is[0].p[2] <= it[0].p[2]
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|| is[1].p[2] <= it[1].p[2])
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{
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/*
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fprintf(stderr, "ignoring collision since z %f < %f || %f < %f\n",
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is[0].p[2], it[0].p[2],
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is[1].p[2], it[1].p[2]);
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*/
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continue;
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}
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// segment is behind the triangle,
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// we have to create a new segment
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// and shorten the existing segment
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// find the two intersections that we have
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// update the src field
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// figure out how far it is to each of the intersections
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const float d00 = v3_len(&s->p[0], &is[0]);
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const float d01 = v3_len(&s->p[0], &is[1]);
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const float d10 = v3_len(&s->p[1], &is[0]);
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@ -747,6 +621,23 @@ fprintf(stderr, "ignoring collision since z %f < %f || %f < %f\n",
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return;
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}
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// if the segment intersection is closer than the triangle,
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// then we do nothing. degenerate cases are not handled
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if (d00 <= d01
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&& is[0].p[2] <= it[0].p[2]
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&& is[1].p[2] <= it[1].p[2])
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continue;
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if (d00 > d01
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&& is[1].p[2] <= it[0].p[2]
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&& is[0].p[2] <= it[1].p[2])
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continue;
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// segment is behind the triangle,
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// we have to create a new segment
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// and shorten the existing segment
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// find the two intersections that we have
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// update the src field
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// we need to create a new segment
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seg_t * news;
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if (d00 < d01)
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@ -785,8 +676,12 @@ seg_print(news);
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// is closer than the triangle intercept, then no problem.
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// we do not bother with degenerate cases of intersecting
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// triangles
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if (is[0].p[2] <= it[0].p[2])
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if (is[0].p[2] <= it[0].p[2]
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&& is[1].p[2] <= it[0].p[2])
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{
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//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
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continue;
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}
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/*
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// due to floating point issues, one of these might
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@ -827,6 +722,7 @@ seg_print(news);
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news->src[1] = s->src[1];
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s->p[0] = is[0];
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tri_seg_intersect(zlist->next, news, slist_visible);
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//svg_line("#00FF00", s->p[0].p, s->p[1].p, 10);
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//fprintf(stderr, "%d -----\n", --recursive);
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// continue splitting our current segment
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