From d48ffe52b4cd64d7c7fe8c92046d8a2a59f20711 Mon Sep 17 00:00:00 2001 From: Trammell hudson Date: Wed, 28 Feb 2018 21:14:52 -0500 Subject: [PATCH] fix list insertion bug and try to trim to a viewport --- hiddenwire.c | 139 ++++++++++++++++++++++++++++++++++++++++++++++++--- 1 file changed, 131 insertions(+), 8 deletions(-) diff --git a/hiddenwire.c b/hiddenwire.c index 1196b97..3ba18e4 100644 --- a/hiddenwire.c +++ b/hiddenwire.c @@ -102,7 +102,7 @@ svg_line( float thick ) { - printf("\n", + printf("\n", p1[0], p1[1], p2[0], @@ -287,6 +287,7 @@ tri_insert( // either we reached the end of the list, // or we have found where our new triangle is sorted t->next = *zlist; + t->prev = zlist; *zlist = t; if (t->next) t->next->prev = &t->next; @@ -448,6 +449,8 @@ tri_coplanar( * setting t0 to 0, this becomes: * p = a * t1 + b * t2 * which is two equations with two unknowns + * + * Returns true if the point is inside the triangle */ int tri_find_z( @@ -702,6 +705,48 @@ return; } +/* + * Fast check to see if t2 is entire occluded by t. + */ +int +tri_behind( + const tri_t * const t, + const tri_t * const t2 +) +{ + float z0, z1, z2; + int inside0 = tri_find_z(t, &t2->p[0], &z0); + int inside1 = tri_find_z(t, &t2->p[1], &z1); + int inside2 = tri_find_z(t, &t2->p[2], &z2); + + // easy check -- if none of the points are inside, + // t2 is not entirely occluded + if (!inside0 || !inside1 || !inside2) + return 0; + + // are all of the intersection points ahead of t2? + int behind0 = t2->p[0].p[2] >= z0; + int behind1 = t2->p[1].p[2] >= z1; + int behind2 = t2->p[2].p[2] >= z2; + if (behind0 && behind1 && behind2) + return 1; + + // it is a STL violation if they are not all on the + // same side (this would indicate that t and t2 intersect + // go ahead and prune since it will cause problems + if (behind0 || behind1 || behind2) + { + fprintf(stderr, "WARNING: triangles intersect %.0f %.0f %.0f inside %d %d %d behind %d %d %d\n", z0, z1, z2, inside0, inside1, inside2, behind0, behind1, behind2); + tri_print(t); + tri_print(t2); + return 1; + } + + // they are all on the same side + return 0; +} + + int v3_parse(v3_t * out, const char * str) { int rc = sscanf(str, "%f,%f,%f", @@ -713,7 +758,27 @@ int v3_parse(v3_t * out, const char * str) return -1; return 0; } - + + +int onscreen( + const v3_t * const p, + const float width, + const float height +) +{ + if (p->p[0] < -width/2 || width/2 < p->p[0]) + return 0; + if (p->p[1] < -height/2 || height/2 < p->p[1]) + return 0; +/* + if (p->p[0] < 0 || width < p->p[0]) + return 0; + if (p->p[1] < 0 || height < p->p[1]) + return 0; +*/ + return 1; +} + int main( int argc, @@ -736,6 +801,8 @@ int main( float scale = 1; float fov = 45; float prune = 0.1; + float width = 4096; + float height = 2048; while((opt = getopt_long(argc, argv ,"h?vBCHc:l:s:u:p:F:", long_options, NULL)) != -1) { @@ -803,10 +870,10 @@ int main( const camera_t * const cam = camera_new(eye, lookat, up, fov, scale); - printf("\n"); + printf("\n", width, height, width, height); - float off_x = 0; - float off_y = 0; + float off_x = 0; // width/2; + float off_y = 0; // height/2; printf("\n", off_x, off_y); int rejected = 0; @@ -815,6 +882,10 @@ int main( seg_t * slist_visible = NULL; int retained = 0; + int backface = 0; + int small_area = 0; + int behind = 0; + int offscreen = 0; // transform the stl by the camera projection and generate // a z-sorted list of triangles @@ -825,7 +896,9 @@ int main( v3_t s[3]; for(int j = 0 ; j < 3 ; j++) + { camera_project(cam, &stl->p[j], &s[j]); + } if(debug >= 2) fprintf(stderr, "%.3f,%.3f,%.3f -> %.1f,%.1f,%.1f\n", @@ -841,32 +914,82 @@ int main( // reject this face if any of the vertices are behind us if (tri->min[2] < 0) + { + behind++; goto reject; + } // do a back-face cull to determine if this triangle // is not facing us. we have to determine the orientation // from the winding of the new projection if (do_backface && tri->normal.p[2] <= 0) + { + backface++; goto reject; + } + + // if it has any off-screen coords, reject it + if (!onscreen(&tri->p[0], width, height) + || !onscreen(&tri->p[1], width, height) + || !onscreen(&tri->p[2], width, height)) + { +tri_print(tri); + offscreen++; + goto reject; + } // prune the small triangles in the screen space if (tri_area_2d(tri) < prune) + { + small_area++; goto reject; + } - retained++; + const float a = v3_dist_2d(&tri->p[0], &tri->p[1]); + const float b = v3_dist_2d(&tri->p[1], &tri->p[2]); + const float c = v3_dist_2d(&tri->p[2], &tri->p[0]); + if( a < prune || b < prune || c < prune) + { + small_area++; + goto reject; + } // it passes the first tests, so insert the triangle // into the list and the three line segments tri_insert(&zlist, tri); + retained++; continue; reject: tri_delete(tri); - rejected++; } if (debug) - fprintf(stderr, "Retained %d, rejected %d triangles\n", retained, rejected); + fprintf(stderr, "Retained %d triangles, rejected %d behind, %d offscreen, %d backface, %d small\n", retained, behind, offscreen, backface, small_area); + + // drop any triangles that are totally occluded by another + // triangle. this reduces the amount of work for later + rejected = 0; + for(tri_t * t = zlist ; t ; t = t->next) + { + tri_t * t2_next; + for(tri_t * t2 = zlist ; t2 ; t2 = t2_next) + { + t2_next = t2->next; + if (t == t2) + continue; + + if (!tri_behind(t, t2)) + continue; + + // t2 is occluded by t, remove it from the list + rejected++; + tri_delete(t2); + } + + } + if (debug) + fprintf(stderr, "Rejected %d fully occluded triangles\n", rejected); // generate a list of segments, dropping any coplanar ones