backported from rtxon: check_clip_poly (needed for new BSP code)

[dosdemo] / src / polyclip.c

diff --git a/src/polyclip.c b/src/polyclip.c
index f5ef9c7..35e6cd6 100644 (file)
--- a/src/polyclip.c
+++ b/src/polyclip.c
@@ -1,3 +1,4 @@
+#include <stdio.h>
 #include <math.h>
 #include <assert.h>
 #include "polyclip.h"
@@ -10,56 +11,83 @@ struct ray {
 static int clip_edge(struct g3d_vertex *poly, int *vnumptr,
                const struct g3d_vertex *v0, const struct g3d_vertex *v1,
                const struct cplane *plane);
+static int check_clip_edge(const struct g3d_vertex *v0,
+               const struct g3d_vertex *v1, const struct cplane *plane);
 static int clip_edge_frustum(struct g3d_vertex *poly, int *vnumptr,
                const struct g3d_vertex *v0, const struct g3d_vertex *v1, int fplane);
 static float distance_signed(float *pos, const struct cplane *plane);
 static int intersect(const struct ray *ray, const struct cplane *plane, float *t);
+static int inside_frustum_plane(const struct g3d_vertex *v, int fplane);
 
 
 int clip_poly(struct g3d_vertex *vout, int *voutnum,
                const struct g3d_vertex *vin, int vnum, struct cplane *plane)
 {
-       int i;
+       int i, nextidx, res;
        int edges_clipped = 0;
-       int out_vnum = 0;
+
+       *voutnum = 0;
 
        for(i=0; i<vnum; i++) {
-               int res = clip_edge(vout, &out_vnum, vin + i, vin + (i + 1) % vnum, plane);
+               nextidx = i + 1;
+               if(nextidx >= vnum) nextidx = 0;
+               res = clip_edge(vout, voutnum, vin + i, vin + nextidx, plane);
                if(res == 0) {
                        ++edges_clipped;
                }
        }
 
-       if(out_vnum <= 0) {
+       if(*voutnum <= 0) {
                assert(edges_clipped == 0);
                return -1;
        }
 
-       *voutnum = out_vnum;
        return edges_clipped > 0 ? 0 : 1;
 }
 
+int check_clip_poly(const struct g3d_vertex *v, int vnum, struct cplane *plane)
+{
+       int i, nextidx, res;
+       int edges_clipped = 0;
+
+       for(i=0; i<vnum; i++) {
+               nextidx = i + 1;
+               if(nextidx >= vnum) nextidx = 0;
+               res = check_clip_edge(v + i, v + nextidx, plane);
+               if(res == 0) {
+                       ++edges_clipped;
+               }
+       }
+       return edges_clipped ? 0 : res;
+}
 
 int clip_frustum(struct g3d_vertex *vout, int *voutnum,
                const struct g3d_vertex *vin, int vnum, int fplane)
 {
-       int i;
+       int i, nextidx, res;
        int edges_clipped = 0;
-       int out_vnum = 0;
+
+       if(vnum == 1) {
+               /* special case: point clipping */
+               return inside_frustum_plane(vin, fplane) ? 1 : -1;
+       }
+
+       *voutnum = 0;
 
        for(i=0; i<vnum; i++) {
-               int res = clip_edge_frustum(vout, &out_vnum, vin + i, vin + (i + 1) % vnum, fplane);
+               nextidx = i + 1;
+               if(nextidx >= vnum) nextidx = 0;
+               res = clip_edge_frustum(vout, voutnum, vin + i, vin + nextidx, fplane);
                if(res == 0) {
                        ++edges_clipped;
                }
        }
 
-       if(out_vnum <= 0) {
+       if(*voutnum <= 0) {
                assert(edges_clipped == 0);
                return -1;
        }
 
-       *voutnum = out_vnum;
        return edges_clipped > 0 ? 0 : 1;
 }
 
@@ -132,9 +160,9 @@ static int clip_edge(struct g3d_vertex *poly, int *vnumptr,
 
                        intersect(&ray, plane, &t);
 
-                       vptr->x = ray.origin[0] + ray.dir[0] + t;
-                       vptr->y = ray.origin[1] + ray.dir[1] + t;
-                       vptr->z = ray.origin[2] + ray.dir[2] + t;
+                       vptr->x = ray.origin[0] + ray.dir[0] * t;
+                       vptr->y = ray.origin[1] + ray.dir[1] * t;
+                       vptr->z = ray.origin[2] + ray.dir[2] * t;
                        vptr->w = 1.0f;
 
                        LERP_VATTR(vptr, v0, v1, t);
@@ -152,6 +180,27 @@ static int clip_edge(struct g3d_vertex *poly, int *vnumptr,
        return 0;
 }
 
+/* same as above, but only checks for clipping and classifies the edge */
+static int check_clip_edge(const struct g3d_vertex *v0,
+               const struct g3d_vertex *v1, const struct cplane *plane)
+{
+       float pos0[3], pos1[3];
+       float d0, d1;
+
+       pos0[0] = v0->x; pos0[1] = v0->y; pos0[2] = v0->z;
+       pos1[0] = v1->x; pos1[1] = v1->y; pos1[2] = v1->z;
+
+       d0 = distance_signed(pos0, plane);
+       d1 = distance_signed(pos1, plane);
+
+       if(d0 > 0.0f && d1 > 0.0f) {
+               return 1;
+       }
+       if(d0 < 0.0f && d1 < 0.0f) {
+               return -1;
+       }
+       return 0;
+}
 
 static float distance_signed(float *pos, const struct cplane *plane)
 {
@@ -166,7 +215,7 @@ static int intersect(const struct ray *ray, const struct cplane *plane, float *t
        float orig_pt_dir[3];
 
        float ndotdir = plane->nx * ray->dir[0] + plane->ny * ray->dir[1] + plane->nz * ray->dir[2];
-       if(fabs(ndotdir) < 1e-4) {
+       if(fabs(ndotdir) < 1e-6) {
                *t = 0.0f;
                return 0;
        }