+++ /dev/null
-#include <stdio.h>
-#include <math.h>
-#include <assert.h>
-#include "polyclip.h"
-
-struct ray {
- float origin[3];
- float dir[3];
-};
-
-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, nextidx, res;
- int edges_clipped = 0;
-
- *voutnum = 0;
-
- for(i=0; i<vnum; i++) {
- nextidx = i + 1;
- if(nextidx >= vnum) nextidx = 0;
- res = clip_edge(vout, voutnum, vin + i, vin + nextidx, plane);
- if(res == 0) {
- ++edges_clipped;
- }
- }
-
- if(*voutnum <= 0) {
- assert(edges_clipped == 0);
- return -1;
- }
-
- 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, nextidx, res;
- int edges_clipped = 0;
-
- if(vnum == 1) {
- /* special case: point clipping */
- return inside_frustum_plane(vin, fplane) ? 1 : -1;
- }
-
- *voutnum = 0;
-
- for(i=0; i<vnum; i++) {
- 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(*voutnum <= 0) {
- assert(edges_clipped == 0);
- return -1;
- }
-
- return edges_clipped > 0 ? 0 : 1;
-}
-
-#define LERP_VATTR(res, v0, v1, t) \
- do { \
- (res)->nx = (v0)->nx + ((v1)->nx - (v0)->nx) * (t); \
- (res)->ny = (v0)->ny + ((v1)->ny - (v0)->ny) * (t); \
- (res)->nz = (v0)->nz + ((v1)->nz - (v0)->nz) * (t); \
- (res)->u = (v0)->u + ((v1)->u - (v0)->u) * (t); \
- (res)->v = (v0)->v + ((v1)->v - (v0)->v) * (t); \
- (res)->r = (v0)->r + ((v1)->r - (v0)->r) * (t); \
- (res)->g = (v0)->g + ((v1)->g - (v0)->g) * (t); \
- (res)->b = (v0)->b + ((v1)->b - (v0)->b) * (t); \
- } while(0)
-
-
-/* returns:
- * 1 -> both inside
- * 0 -> straddling and clipped
- * -1 -> both outside
- *
- * also returns the size of the polygon through vnumptr
- */
-static int clip_edge(struct g3d_vertex *poly, int *vnumptr,
- const struct g3d_vertex *v0, const struct g3d_vertex *v1,
- const struct cplane *plane)
-{
- float pos0[3], pos1[3];
- float d0, d1, t;
- struct ray ray;
- int i, vnum = *vnumptr;
-
- 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);
-
- for(i=0; i<3; i++) {
- ray.origin[i] = pos0[i];
- ray.dir[i] = pos1[i] - pos0[i];
- }
-
- if(d0 >= 0.0) {
- /* start inside */
- if(d1 >= 0.0) {
- /* all inside */
- poly[vnum++] = *v1; /* append v1 */
- *vnumptr = vnum;
- return 1;
- } else {
- /* going out */
- struct g3d_vertex *vptr = poly + vnum;
-
- 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->w = 1.0f;
-
- LERP_VATTR(vptr, v0, v1, t);
- vnum++; /* append new vertex on the intersection point */
- }
- } else {
- /* start outside */
- if(d1 >= 0) {
- /* going in */
- struct g3d_vertex *vptr = poly + vnum;
-
- 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->w = 1.0f;
-
- LERP_VATTR(vptr, v0, v1, t);
- vnum++; /* append new vertex on the intersection point */
-
- /* then append v1 ... */
- poly[vnum++] = *v1;
- } else {
- /* all outside */
- return -1;
- }
- }
-
- *vnumptr = vnum;
- 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)
-{
- float dx = pos[0] - plane->x;
- float dy = pos[1] - plane->y;
- float dz = pos[2] - plane->z;
- return dx * plane->nx + dy * plane->ny + dz * plane->nz;
-}
-
-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-6) {
- *t = 0.0f;
- return 0;
- }
-
- orig_pt_dir[0] = plane->x - ray->origin[0];
- orig_pt_dir[1] = plane->y - ray->origin[1];
- orig_pt_dir[2] = plane->z - ray->origin[2];
-
- *t = (plane->nx * orig_pt_dir[0] + plane->ny * orig_pt_dir[1] + plane->nz * orig_pt_dir[2]) / ndotdir;
- return 1;
-}
-
-/* homogeneous frustum clipper helpers */
-
-static int inside_frustum_plane(const struct g3d_vertex *v, int fplane)
-{
- switch(fplane) {
- case CLIP_LEFT:
- return v->x >= -v->w;
- case CLIP_RIGHT:
- return v->x <= v->w;
- case CLIP_BOTTOM:
- return v->y >= -v->w;
- case CLIP_TOP:
- return v->y <= v->w;
- case CLIP_NEAR:
- return v->z >= -v->w;
- case CLIP_FAR:
- return v->z <= v->w;
- }
- assert(0);
- return 0;
-}
-
-static float intersect_frustum(const struct g3d_vertex *a, const struct g3d_vertex *b, int fplane)
-{
- switch(fplane) {
- case CLIP_LEFT:
- return (-a->w - a->x) / (b->x - a->x + b->w - a->w);
- case CLIP_RIGHT:
- return (a->w - a->x) / (b->x - a->x - b->w + a->w);
- case CLIP_BOTTOM:
- return (-a->w - a->y) / (b->y - a->y + b->w - a->w);
- case CLIP_TOP:
- return (a->w - a->y) / (b->y - a->y - b->w + a->w);
- case CLIP_NEAR:
- return (-a->w - a->z) / (b->z - a->z + b->w - a->w);
- case CLIP_FAR:
- return (a->w - a->z) / (b->z - a->z - b->w + a->w);
- }
-
- assert(0);
- return 0;
-}
-
-static int clip_edge_frustum(struct g3d_vertex *poly, int *vnumptr,
- const struct g3d_vertex *v0, const struct g3d_vertex *v1, int fplane)
-{
- int vnum = *vnumptr;
- int in0, in1;
- float t;
-
- in0 = inside_frustum_plane(v0, fplane);
- in1 = inside_frustum_plane(v1, fplane);
-
- if(in0) {
- /* start inside */
- if(in1) {
- /* all inside */
- poly[vnum++] = *v1; /* append v1 */
- *vnumptr = vnum;
- return 1;
- } else {
- /* going out */
- struct g3d_vertex *vptr = poly + vnum;
-
- t = intersect_frustum(v0, v1, fplane);
-
- vptr->x = v0->x + (v1->x - v0->x) * t;
- vptr->y = v0->y + (v1->y - v0->y) * t;
- vptr->z = v0->z + (v1->z - v0->z) * t;
- vptr->w = v0->w + (v1->w - v0->w) * t;
-
- LERP_VATTR(vptr, v0, v1, t);
- ++vnum; /* append new vertex on the intersection point */
- }
- } else {
- /* start outside */
- if(in1) {
- /* going in */
- struct g3d_vertex *vptr = poly + vnum;
-
- t = intersect_frustum(v0, v1, fplane);
-
- vptr->x = v0->x + (v1->x - v0->x) * t;
- vptr->y = v0->y + (v1->y - v0->y) * t;
- vptr->z = v0->z + (v1->z - v0->z) * t;
- vptr->w = v0->w + (v1->w - v0->w) * t;
-
- LERP_VATTR(vptr, v0, v1, t);
- ++vnum; /* append new vertex on the intersection point */
-
- /* then append v1 ... */
- poly[vnum++] = *v1;
- } else {
- /* all outside */
- return -1;
- }
- }
-
- *vnumptr = vnum;
- return 0;
-}
projects / dosdemo / blobdiff