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-rw-r--r--src/VBox/HostServices/SharedOpenGL/crserverlib/server_clip.c588
1 files changed, 588 insertions, 0 deletions
diff --git a/src/VBox/HostServices/SharedOpenGL/crserverlib/server_clip.c b/src/VBox/HostServices/SharedOpenGL/crserverlib/server_clip.c
new file mode 100644
index 00000000..03143b0d
--- /dev/null
+++ b/src/VBox/HostServices/SharedOpenGL/crserverlib/server_clip.c
@@ -0,0 +1,588 @@
+/* Copyright (c) 2001, Stanford University
+ * All rights reserved
+ *
+ * See the file LICENSE.txt for information on redistributing this software.
+ */
+
+/*
+ * This code contributed by Karl Rasche <rkarl@vr.clemson.edu>
+ */
+
+
+#include <math.h>
+
+#include "cr_server.h"
+#include "cr_mem.h"
+#include "server.h"
+
+
+static void
+__find_intersection(double *s, double *e, double *clp, double *clp_next,
+ double *intr)
+{
+ double v1[2], v2[2];
+ double A, B, T;
+
+ v1[0] = e[0] - s[0];
+ v1[1] = e[1] - s[1];
+ v2[0] = clp_next[0] - clp[0];
+ v2[1] = clp_next[1] - clp[1];
+
+ if ((v1[1]) && (v2[0]))
+ {
+ A = (clp[1]-s[1])/v1[1] + (v2[1]/v1[1])*(s[0]-clp[0])/v2[0];
+ B = 1.-(v2[1]/v1[1])*(v1[0]/v2[0]);
+ if (B)
+ T = A/B;
+ else
+ {
+ T = 0;
+ }
+
+ intr[0] = s[0]+T*v1[0];
+ intr[1] = s[1]+T*v1[1];
+ }
+ else
+ if (v1[1])
+ {
+ /* clp -> clp_next is vertical */
+ T = (clp[0]-s[0])/v1[0];
+
+ intr[0] = s[0]+T*v1[0];
+ intr[1] = s[1]+T*v1[1];
+ }
+ else
+ {
+ /* s -> e is horizontal */
+ T = (s[1]-clp[1])/v2[1];
+
+ intr[0] = clp[0]+T*v2[0];
+ intr[1] = clp[1]+T*v2[1];
+ }
+
+}
+
+static void
+ __clip_one_side(double *poly, int npnts, double *clp, double *clp_next,
+ double *norm,
+ double **new_poly_in, int *new_npnts_in,
+ double **new_poly_out, int *new_npnts_out)
+{
+ int a, sin, ein;
+ double *s, *e, intr[2];
+
+ *new_poly_in = (double *)crAlloc(2*npnts*2*sizeof(double));
+ *new_npnts_in = 0;
+
+ *new_poly_out = (double *)crAlloc(2*npnts*2*sizeof(double));
+ *new_npnts_out = 0;
+
+ s = poly;
+
+ for (a=0; a<npnts; a++)
+ {
+ e = poly+2*((a+1)%npnts);
+
+ if (((e[0]-clp[0])*norm[0]) + ((e[1]-clp[1])*norm[1]) >= 0)
+ ein = 0;
+ else
+ ein = 1;
+
+ if (((s[0]-clp[0])*norm[0]) + ((s[1]-clp[1])*norm[1]) >= 0)
+ sin = 0;
+ else
+ sin = 1;
+
+ if (sin && ein)
+ {
+ /* case 1: */
+ crMemcpy(*new_poly_in+2*(*new_npnts_in), e, 2*sizeof(double));
+ (*new_npnts_in)++;
+ }
+ else
+ if (sin && (!ein))
+ {
+ /* case 2: */
+
+ __find_intersection(s, e, clp, clp_next, intr);
+
+ crMemcpy(*new_poly_in+2*(*new_npnts_in), intr, 2*sizeof(double));
+ (*new_npnts_in)++;
+
+ crMemcpy(*new_poly_out+2*(*new_npnts_out), intr, 2*sizeof(double));
+ (*new_npnts_out)++;
+ crMemcpy(*new_poly_out+2*(*new_npnts_out), e, 2*sizeof(double));
+ (*new_npnts_out)++;
+ }
+ else
+ if ((!sin) && ein)
+ {
+ /* case 4: */
+ __find_intersection(s, e, clp, clp_next, intr);
+
+ crMemcpy((*new_poly_in)+2*(*new_npnts_in), intr, 2*sizeof(double));
+ (*new_npnts_in)++;
+ crMemcpy((*new_poly_in)+2*(*new_npnts_in), e, 2*sizeof(double));
+ (*new_npnts_in)++;
+
+ crMemcpy(*new_poly_out+2*(*new_npnts_out), intr, 2*sizeof(double));
+ (*new_npnts_out)++;
+ }
+ else
+ {
+ crMemcpy(*new_poly_out+2*(*new_npnts_out), e, 2*sizeof(double));
+ (*new_npnts_out)++;
+ }
+
+ s = e;
+ }
+}
+
+/*
+ * Sutherland/Hodgman clipping for interior & exterior regions.
+ * length_of((*new_vert_out)[a]) == nclip_to_vert
+ */
+static void
+__clip(double *poly, int nvert, double *clip_to_poly, int nclip_to_vert,
+ double **new_vert_in, int *nnew_vert_in,
+ double ***new_vert_out, int **nnew_vert_out)
+{
+ int a, side, *nout;
+ double *clip_normals, *s, *e, *n, *new_vert_src;
+ double *norm, *clp, *clp_next;
+ double **out;
+
+ *new_vert_out = (double **)crAlloc(nclip_to_vert*sizeof(double *));
+ *nnew_vert_out = (int *)crAlloc(nclip_to_vert*sizeof(int));
+
+ /*
+ * First, compute normals for the clip poly. This
+ * breaks for multiple (3+) adjacent colinear vertices
+ */
+ clip_normals = (double *)crAlloc(nclip_to_vert*2*sizeof(double));
+ for (a=0; a<nclip_to_vert; a++)
+ {
+ s = clip_to_poly+2*a;
+ e = clip_to_poly+2*((a+1)%nclip_to_vert);
+ n = clip_to_poly+2*((a+2)%nclip_to_vert);
+
+ norm = clip_normals+2*a;
+ norm[0] = e[1]-s[1];
+ norm[1] = -1*(e[0]-s[0]);
+
+ /*
+ * if dot(norm, n-e) > 0), the normals are backwards,
+ * assuming the clip region is convex
+ */
+ if (norm[0]*(n[0]-e[0]) + norm[1]*(n[1]-e[1]) > 0)
+ {
+ norm[0] *= -1;
+ norm[1] *= -1;
+ }
+ }
+
+ new_vert_src = (double *)crAlloc(nvert*nclip_to_vert*2*sizeof(double));
+ crMemcpy(new_vert_src, poly, 2*nvert*sizeof(double));
+
+ for (side=0; side<nclip_to_vert; side++)
+ {
+ clp = clip_to_poly+2*side;
+ clp_next = clip_to_poly+2*((side+1)%nclip_to_vert);
+ norm = clip_normals+2*side;
+ *nnew_vert_in = 0;
+
+ nout = (*nnew_vert_out)+side;
+ out = (*new_vert_out)+side;
+
+ __clip_one_side(new_vert_src, nvert, clp, clp_next, norm,
+ new_vert_in, nnew_vert_in,
+ out, nout);
+
+ crMemcpy(new_vert_src, (*new_vert_in), 2*(*nnew_vert_in)*sizeof(double));
+ if (side != nclip_to_vert-1)
+ crFree(*new_vert_in);
+ nvert = *nnew_vert_in;
+ }
+}
+
+/*
+ * Given a bitmap and a group of 'base' polygons [the quads we are testing],
+ * perform the unions and differences specified by the map and return
+ * the resulting geometry
+ */
+static void
+__execute_combination(CRPoly **base, int n, int *mask, CRPoly **head)
+{
+ int a, b, got_intr;
+ int nin, *nout, last;
+ double *in, **out;
+ CRPoly *intr, *diff, *p;
+
+ *head = NULL;
+
+ intr = (CRPoly *)crAlloc(sizeof(CRPoly));
+ intr->next = NULL;
+
+ got_intr = 0;
+
+ /* first, intersect the first 2 polys marked */
+ for (a=0; a<n; a++)
+ if (mask[a]) break;
+ for (b=a+1; b<n; b++)
+ if (mask[b]) break;
+
+ __clip(base[a]->points, base[a]->npoints,
+ base[b]->points, base[b]->npoints,
+ &in, &nin, &out, &nout);
+ last = b;
+
+ crFree (nout);
+ for (a=0; a<base[last]->npoints; a++)
+ if (out[a])
+ crFree(out[a]);
+ crFree(out);
+
+
+ if (nin)
+ {
+ intr->npoints = nin;
+ intr->points = in;
+ got_intr = 1;
+ }
+
+ while (1)
+ {
+ for (a=last+1; a<n; a++)
+ if (mask[a]) break;
+
+ if (a == n) break;
+
+ if (got_intr)
+ {
+ __clip(base[a]->points, base[a]->npoints,
+ intr->points, intr->npoints,
+ &in, &nin, &out, &nout);
+
+ crFree (nout);
+ for (b=0; b<intr->npoints; b++)
+ if (out[b])
+ crFree(out[b]);
+ crFree(out);
+
+ if (nin)
+ {
+ intr->npoints = nin;
+ intr->points = in;
+ }
+ else
+ {
+ got_intr = 0;
+ break;
+ }
+ }
+ else
+ {
+ __clip(base[a]->points, base[a]->npoints,
+ base[last]->points, base[last]->npoints,
+ &in, &nin, &out, &nout);
+
+ crFree (nout);
+ for (b=0; b<base[last]->npoints; b++)
+ {
+ if (out[b])
+ crFree(out[b]);
+ }
+ crFree(out);
+
+
+ if (nin)
+ {
+ intr->npoints = nin;
+ intr->points = in;
+ got_intr = 1;
+ }
+ }
+
+ last = a;
+ if (a == n) break;
+ }
+
+ /* can't subtract something from nothing! */
+ if (got_intr)
+ *head = intr;
+ else
+ return;
+
+ /* find the first item to subtract */
+ for (a=0; a<n; a++)
+ if (!mask[a]) break;
+
+ if (a == n) return;
+ last = a;
+
+ /* and subtract it */
+ diff = NULL;
+ __clip(intr->points, intr->npoints,
+ base[last]->points, base[last]->npoints,
+ &in, &nin, &out, &nout);
+
+ crFree(in);
+
+ for (a=0; a<base[last]->npoints; a++)
+ {
+ if (!nout[a]) continue;
+
+ p = (CRPoly *)crAlloc(sizeof(CRPoly));
+ p->npoints = nout[a];
+ p->points = out[a];
+ p->next = diff;
+ diff = p;
+ }
+ *head = diff;
+
+ while (1)
+ {
+ intr = diff;
+ diff = NULL;
+
+ for (a=last+1; a<n; a++)
+ if (!mask[a]) break;
+ if (a == n) return;
+
+ last = a;
+
+ /* subtract mask[a] from everything in intr and
+ * plop it into diff */
+ while (intr)
+ {
+ __clip(intr->points, intr->npoints,
+ base[last]->points, base[last]->npoints,
+ &in, &nin, &out, &nout);
+
+ crFree(in);
+
+ for (a=0; a<base[last]->npoints; a++)
+ {
+ if (!nout[a]) continue;
+
+ p = (CRPoly *)crAlloc(sizeof(CRPoly));
+ p->npoints = nout[a];
+ p->points = out[a];
+ p->next = diff;
+ diff = p;
+ }
+
+ intr = intr->next;
+ }
+
+ *head = diff;
+ }
+
+}
+
+/*
+ * Here we generate all valid bitmaps to represent union/difference
+ * combinations. Each bitmap is N elements long, where N is the
+ * number of polys [quads] that we are testing for overlap
+ */
+static void
+__generate_masks(int n, int ***mask, int *nmasks)
+{
+ int a, b, c, d, e;
+ int i, idx, isec_size, add;
+
+ *mask = (int **)crAlloc((unsigned int)pow(2, n)*sizeof(int));
+ for (a=0; a<pow(2, n); a++)
+ (*mask)[a] = (int *)crAlloc(n*sizeof(int));
+
+ /* compute combinations */
+ idx = 0;
+ for (isec_size=1; isec_size<n; isec_size++)
+ {
+ for (a=0; a<n; a++)
+ {
+ for (b=a+1; b<n; b++)
+ {
+ crMemset((*mask)[idx], 0, n*sizeof(int));
+ (*mask)[idx][a] = 1;
+
+ add = 1;
+ for (c=0; c<isec_size; c++)
+ {
+ i = (b+c) % n;
+ if (i == a) add = 0;
+
+ (*mask)[idx][i] = 1;
+ }
+
+ /* dup check */
+ if ((add) && (idx))
+ {
+ for (d=0; d<idx; d++)
+ {
+ add = 0;
+ for (e=0; e<n; e++)
+ {
+ if ((*mask)[idx][e] != (*mask)[d][e])
+ add = 1;
+ }
+
+ if (!add)
+ break;
+ }
+ }
+
+ if (add)
+ idx++;
+ }
+ }
+ }
+
+ *nmasks = idx;
+}
+
+/*
+ * To compute the overlap between a series of quads (This should work
+ * for n-gons, but we'll only need quads..), first generate a series of
+ * bitmaps that represent which elements to union together, and which
+ * to difference. This goes into 'mask'. We then evaluate each bitmap with
+ * Sutherland-Hodgman clipping to find the interior (union) and exterior
+ * (difference) regions.
+ *
+ * In the map, 1 == union, 0 == difference
+ *
+ * (*res)[a] is the head of a poly list for all the polys that convert
+ * regions of overlap between a+1 polys ((*res)[0] == NULL)
+ */
+void
+crComputeOverlapGeom(double *quads, int nquad, CRPoly ***res)
+{
+ int a, b, idx, isec_size, **mask;
+ CRPoly *p, *next, **base;
+
+ base = (CRPoly **)crAlloc(nquad*sizeof(CRPoly *));
+ for (a=0; a<nquad; a++)
+ {
+ p = (CRPoly *)crAlloc(sizeof(CRPoly));
+ p->npoints = 4;
+ p->points = (double *)crAlloc(8*sizeof(double));
+ for (b=0; b<8; b++)
+ {
+ p->points[b] = quads[8*a+b];
+ }
+ p->next = NULL;
+ base[a] = p;
+ }
+
+ *res = (CRPoly **)crAlloc(nquad*sizeof(CRPoly *));
+ for (a=0; a<nquad; a++)
+ (*res)[a] = NULL;
+
+ __generate_masks(nquad, &mask, &idx);
+
+ for (a=0; a<idx; a++)
+ {
+ isec_size = 0;
+ for (b=0; b<nquad; b++)
+ if (mask[a][b]) isec_size++;
+ isec_size--;
+
+ __execute_combination(base, nquad, mask[a], &p);
+
+ while (p)
+ {
+ next = p->next;
+
+ p->next = (*res)[isec_size];
+ (*res)[isec_size] = p;
+
+ p = next;
+ }
+ }
+
+ for (a=0; a<nquad; a++)
+ {
+ crFree(base[a]->points);
+ crFree(base[a]);
+ }
+ crFree(base);
+
+}
+
+/*
+ * This is similar to ComputeOverlapGeom above, but for "knockout"
+ * edge blending.
+ *
+ * my_quad_idx is an index of quads indicating which display tile
+ * we are computing geometry for. From this, we either generate
+ * geometry, or not, such that all geometry can be drawn in black
+ * and only one tile will show through the blend as non-black.
+ *
+ * To add a combination to our set of geom, we must test that:
+ * + mask[a][my_quad_idx] is set
+ * + mask[a][my_quad_idx] is not the first element set in
+ * mask[a].
+ * If these conditions hold, execute mask[a] and draw the resulting
+ * geometry in black
+ *
+ * Unlike ComputeOverlapGeom, res is just a list of polys to draw in black
+ */
+void
+crComputeKnockoutGeom(double *quads, int nquad, int my_quad_idx, CRPoly **res)
+{
+ int a, b, idx, first, **mask;
+ CRPoly *p, *next, **base;
+
+ base = (CRPoly **) crAlloc(nquad*sizeof(CRPoly *));
+ for (a=0; a<nquad; a++)
+ {
+ p = (CRPoly *) crAlloc(sizeof(CRPoly));
+ p->npoints = 4;
+ p->points = (double *) crAlloc(8*sizeof(double));
+ for (b=0; b<8; b++)
+ {
+ p->points[b] = quads[8*a+b];
+ }
+ p->next = NULL;
+ base[a] = p;
+ }
+
+ (*res) = NULL;
+
+ __generate_masks(nquad, &mask, &idx);
+
+ for (a=0; a<idx; a++)
+ {
+ /* test for above conditions */
+ if (!mask[a][my_quad_idx]) continue;
+
+ first = -1;
+ for (b=0; b<nquad; b++)
+ if (mask[a][b])
+ {
+ first = b;
+ break;
+ }
+ if (first == my_quad_idx) continue;
+
+
+ __execute_combination(base, nquad, mask[a], &p);
+
+ while (p)
+ {
+ next = p->next;
+
+ p->next = *res;
+ *res = p;
+
+ p = next;
+ }
+ }
+
+ for (a=0; a<nquad; a++)
+ {
+ crFree(base[a]->points);
+ crFree(base[a]);
+ }
+ crFree(base);
+}
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