| 1 | /* Copyright (c) 2001, Stanford University
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| 2 | * All rights reserved
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| 3 | *
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| 4 | * See the file LICENSE.txt for information on redistributing this software.
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| 5 | */
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| 6 |
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| 7 | /*
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| 8 | * This code contributed by Karl Rasche <[email protected]>
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| 9 | */
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| 10 |
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| 11 |
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| 12 | #include <math.h>
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| 13 | #include "cr_server.h"
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| 14 | #include "cr_mem.h"
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| 15 | #include "server.h"
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| 16 |
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| 17 |
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| 18 | static void
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| 19 | __find_intersection(double *s, double *e, double *clp, double *clp_next,
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| 20 | double *intr)
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| 21 | {
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| 22 | double v1[2], v2[2];
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| 23 | double A, B, T;
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| 24 |
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| 25 | v1[0] = e[0] - s[0];
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| 26 | v1[1] = e[1] - s[1];
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| 27 | v2[0] = clp_next[0] - clp[0];
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| 28 | v2[1] = clp_next[1] - clp[1];
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| 29 |
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| 30 | if ((v1[1]) && (v2[0]))
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| 31 | {
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| 32 | A = (clp[1]-s[1])/v1[1] + (v2[1]/v1[1])*(s[0]-clp[0])/v2[0];
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| 33 | B = 1.-(v2[1]/v1[1])*(v1[0]/v2[0]);
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| 34 | if (B)
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| 35 | T = A/B;
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| 36 | else
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| 37 | {
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| 38 | T = 0;
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| 39 | }
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| 40 |
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| 41 | intr[0] = s[0]+T*v1[0];
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| 42 | intr[1] = s[1]+T*v1[1];
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| 43 | }
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| 44 | else
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| 45 | if (v1[1])
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| 46 | {
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| 47 | /* clp -> clp_next is vertical */
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| 48 | T = (clp[0]-s[0])/v1[0];
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| 49 |
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| 50 | intr[0] = s[0]+T*v1[0];
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| 51 | intr[1] = s[1]+T*v1[1];
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| 52 | }
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| 53 | else
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| 54 | {
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| 55 | /* s -> e is horizontal */
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| 56 | T = (s[1]-clp[1])/v2[1];
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| 57 |
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| 58 | intr[0] = clp[0]+T*v2[0];
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| 59 | intr[1] = clp[1]+T*v2[1];
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| 60 | }
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| 61 |
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| 62 | }
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| 63 |
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| 64 | static void
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| 65 | __clip_one_side(double *poly, int npnts, double *clp, double *clp_next,
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| 66 | double *norm,
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| 67 | double **new_poly_in, int *new_npnts_in,
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| 68 | double **new_poly_out, int *new_npnts_out)
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| 69 | {
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| 70 | int a, sin, ein;
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| 71 | double *s, *e, intr[2];
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| 72 |
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| 73 | *new_poly_in = (double *)crAlloc(2*npnts*2*sizeof(double));
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| 74 | *new_npnts_in = 0;
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| 75 |
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| 76 | *new_poly_out = (double *)crAlloc(2*npnts*2*sizeof(double));
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| 77 | *new_npnts_out = 0;
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| 78 |
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| 79 | s = poly;
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| 80 |
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| 81 | for (a=0; a<npnts; a++)
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| 82 | {
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| 83 | e = poly+2*((a+1)%npnts);
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| 84 |
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| 85 | if (((e[0]-clp[0])*norm[0]) + ((e[1]-clp[1])*norm[1]) >= 0)
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| 86 | ein = 0;
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| 87 | else
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| 88 | ein = 1;
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| 89 |
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| 90 | if (((s[0]-clp[0])*norm[0]) + ((s[1]-clp[1])*norm[1]) >= 0)
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| 91 | sin = 0;
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| 92 | else
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| 93 | sin = 1;
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| 94 |
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| 95 | if (sin && ein)
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| 96 | {
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| 97 | /* case 1: */
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| 98 | crMemcpy(*new_poly_in+2*(*new_npnts_in), e, 2*sizeof(double));
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| 99 | (*new_npnts_in)++;
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| 100 | }
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| 101 | else
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| 102 | if (sin && (!ein))
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| 103 | {
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| 104 | /* case 2: */
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| 105 |
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| 106 | __find_intersection(s, e, clp, clp_next, intr);
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| 107 |
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| 108 | crMemcpy(*new_poly_in+2*(*new_npnts_in), intr, 2*sizeof(double));
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| 109 | (*new_npnts_in)++;
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| 110 |
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| 111 | crMemcpy(*new_poly_out+2*(*new_npnts_out), intr, 2*sizeof(double));
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| 112 | (*new_npnts_out)++;
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| 113 | crMemcpy(*new_poly_out+2*(*new_npnts_out), e, 2*sizeof(double));
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| 114 | (*new_npnts_out)++;
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| 115 | }
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| 116 | else
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| 117 | if ((!sin) && ein)
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| 118 | {
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| 119 | /* case 4: */
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| 120 | __find_intersection(s, e, clp, clp_next, intr);
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| 121 |
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| 122 | crMemcpy((*new_poly_in)+2*(*new_npnts_in), intr, 2*sizeof(double));
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| 123 | (*new_npnts_in)++;
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| 124 | crMemcpy((*new_poly_in)+2*(*new_npnts_in), e, 2*sizeof(double));
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| 125 | (*new_npnts_in)++;
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| 126 |
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| 127 | crMemcpy(*new_poly_out+2*(*new_npnts_out), intr, 2*sizeof(double));
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| 128 | (*new_npnts_out)++;
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| 129 | }
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| 130 | else
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| 131 | {
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| 132 | crMemcpy(*new_poly_out+2*(*new_npnts_out), e, 2*sizeof(double));
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| 133 | (*new_npnts_out)++;
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| 134 | }
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| 135 |
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| 136 | s = e;
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| 137 | }
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| 138 | }
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| 139 |
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| 140 | /*
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| 141 | * Sutherland/Hodgman clipping for interior & exterior regions.
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| 142 | * length_of((*new_vert_out)[a]) == nclip_to_vert
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| 143 | */
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| 144 | static void
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| 145 | __clip(double *poly, int nvert, double *clip_to_poly, int nclip_to_vert,
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| 146 | double **new_vert_in, int *nnew_vert_in,
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| 147 | double ***new_vert_out, int **nnew_vert_out)
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| 148 | {
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| 149 | int a, side, *nout;
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| 150 | double *clip_normals, *s, *e, *n, *new_vert_src;
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| 151 | double *norm, *clp, *clp_next;
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| 152 | double **out;
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| 153 |
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| 154 | *new_vert_out = (double **)crAlloc(nclip_to_vert*sizeof(double *));
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| 155 | *nnew_vert_out = (int *)crAlloc(nclip_to_vert*sizeof(int));
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| 156 |
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| 157 | /*
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| 158 | * First, compute normals for the clip poly. This
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| 159 | * breaks for multiple (3+) adjacent colinear vertices
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| 160 | */
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| 161 | clip_normals = (double *)crAlloc(nclip_to_vert*2*sizeof(double));
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| 162 | for (a=0; a<nclip_to_vert; a++)
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| 163 | {
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| 164 | s = clip_to_poly+2*a;
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| 165 | e = clip_to_poly+2*((a+1)%nclip_to_vert);
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| 166 | n = clip_to_poly+2*((a+2)%nclip_to_vert);
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| 167 |
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| 168 | norm = clip_normals+2*a;
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| 169 | norm[0] = e[1]-s[1];
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| 170 | norm[1] = -1*(e[0]-s[0]);
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| 171 |
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| 172 | /*
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| 173 | * if dot(norm, n-e) > 0), the normals are backwards,
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| 174 | * assuming the clip region is convex
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| 175 | */
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| 176 | if (norm[0]*(n[0]-e[0]) + norm[1]*(n[1]-e[1]) > 0)
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| 177 | {
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| 178 | norm[0] *= -1;
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| 179 | norm[1] *= -1;
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| 180 | }
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| 181 | }
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| 182 |
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| 183 | new_vert_src = (double *)crAlloc(nvert*nclip_to_vert*2*sizeof(double));
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| 184 | crMemcpy(new_vert_src, poly, 2*nvert*sizeof(double));
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| 185 |
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| 186 | for (side=0; side<nclip_to_vert; side++)
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| 187 | {
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| 188 | clp = clip_to_poly+2*side;
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| 189 | clp_next = clip_to_poly+2*((side+1)%nclip_to_vert);
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| 190 | norm = clip_normals+2*side;
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| 191 | *nnew_vert_in = 0;
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| 192 |
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| 193 | nout = (*nnew_vert_out)+side;
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| 194 | out = (*new_vert_out)+side;
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| 195 |
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| 196 | __clip_one_side(new_vert_src, nvert, clp, clp_next, norm,
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| 197 | new_vert_in, nnew_vert_in,
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| 198 | out, nout);
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| 199 |
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| 200 | crMemcpy(new_vert_src, (*new_vert_in), 2*(*nnew_vert_in)*sizeof(double));
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| 201 | if (side != nclip_to_vert-1)
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| 202 | crFree(*new_vert_in);
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| 203 | nvert = *nnew_vert_in;
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| 204 | }
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| 205 | }
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| 206 |
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| 207 | /*
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| 208 | * Given a bitmap and a group of 'base' polygons [the quads we are testing],
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| 209 | * perform the unions and differences specified by the map and return
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| 210 | * the resulting geometry
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| 211 | */
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| 212 | static void
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| 213 | __execute_combination(CRPoly **base, int n, int *mask, CRPoly **head)
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| 214 | {
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| 215 | int a, b, got_intr;
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| 216 | int nin, *nout, last;
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| 217 | double *in, **out;
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| 218 | CRPoly *intr, *diff, *p;
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| 219 |
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| 220 | *head = NULL;
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| 221 |
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| 222 | intr = (CRPoly *)crAlloc(sizeof(CRPoly));
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| 223 | intr->next = NULL;
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| 224 |
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| 225 | got_intr = 0;
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| 226 |
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| 227 | /* first, intersect the first 2 polys marked */
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| 228 | for (a=0; a<n; a++)
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| 229 | if (mask[a]) break;
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| 230 | for (b=a+1; b<n; b++)
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| 231 | if (mask[b]) break;
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| 232 |
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| 233 | __clip(base[a]->points, base[a]->npoints,
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| 234 | base[b]->points, base[b]->npoints,
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| 235 | &in, &nin, &out, &nout);
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| 236 | last = b;
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| 237 |
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| 238 | crFree (nout);
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| 239 | for (a=0; a<base[last]->npoints; a++)
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| 240 | if (out[a])
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| 241 | crFree(out[a]);
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| 242 | crFree(out);
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| 243 |
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| 244 |
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| 245 | if (nin)
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| 246 | {
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| 247 | intr->npoints = nin;
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| 248 | intr->points = in;
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| 249 | got_intr = 1;
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| 250 | }
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| 251 |
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| 252 | while (1)
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| 253 | {
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| 254 | for (a=last+1; a<n; a++)
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| 255 | if (mask[a]) break;
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| 256 |
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| 257 | if (a == n) break;
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| 258 |
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| 259 | if (got_intr)
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| 260 | {
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| 261 | __clip(base[a]->points, base[a]->npoints,
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| 262 | intr->points, intr->npoints,
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| 263 | &in, &nin, &out, &nout);
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| 264 |
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| 265 | crFree (nout);
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| 266 | for (b=0; b<intr->npoints; b++)
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| 267 | if (out[b])
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| 268 | crFree(out[b]);
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| 269 | crFree(out);
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| 270 |
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| 271 | if (nin)
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| 272 | {
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| 273 | intr->npoints = nin;
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| 274 | intr->points = in;
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| 275 | }
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| 276 | else
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| 277 | {
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| 278 | got_intr = 0;
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| 279 | break;
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| 280 | }
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| 281 | }
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| 282 | else
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| 283 | {
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| 284 | __clip(base[a]->points, base[a]->npoints,
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| 285 | base[last]->points, base[last]->npoints,
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| 286 | &in, &nin, &out, &nout);
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| 287 |
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| 288 | crFree (nout);
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| 289 | for (b=0; b<base[last]->npoints; b++)
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| 290 | {
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| 291 | if (out[b])
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| 292 | crFree(out[b]);
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| 293 | }
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| 294 | crFree(out);
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| 295 |
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| 296 |
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| 297 | if (nin)
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| 298 | {
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| 299 | intr->npoints = nin;
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| 300 | intr->points = in;
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| 301 | got_intr = 1;
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| 302 | }
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| 303 | }
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| 304 |
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| 305 | last = a;
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| 306 | if (a == n) break;
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| 307 | }
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| 308 |
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| 309 | /* can't subtract something from nothing! */
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| 310 | if (got_intr)
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| 311 | *head = intr;
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| 312 | else
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| 313 | return;
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| 314 |
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| 315 | /* find the first item to subtract */
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| 316 | for (a=0; a<n; a++)
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| 317 | if (!mask[a]) break;
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| 318 |
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| 319 | if (a == n) return;
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| 320 | last = a;
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| 321 |
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| 322 | /* and subtract it */
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| 323 | diff = NULL;
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| 324 | __clip(intr->points, intr->npoints,
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| 325 | base[last]->points, base[last]->npoints,
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| 326 | &in, &nin, &out, &nout);
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| 327 |
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| 328 | crFree(in);
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| 329 |
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| 330 | for (a=0; a<base[last]->npoints; a++)
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| 331 | {
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| 332 | if (!nout[a]) continue;
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| 333 |
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| 334 | p = (CRPoly *)crAlloc(sizeof(CRPoly));
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| 335 | p->npoints = nout[a];
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| 336 | p->points = out[a];
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| 337 | p->next = diff;
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| 338 | diff = p;
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| 339 | }
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| 340 | *head = diff;
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| 341 |
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| 342 | while (1)
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| 343 | {
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| 344 | intr = diff;
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| 345 | diff = NULL;
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| 346 |
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| 347 | for (a=last+1; a<n; a++)
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| 348 | if (!mask[a]) break;
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| 349 | if (a == n) return;
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| 350 |
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| 351 | last = a;
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| 352 |
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| 353 | /* subtract mask[a] from everything in intr and
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| 354 | * plop it into diff */
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| 355 | while (intr)
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| 356 | {
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| 357 | __clip(intr->points, intr->npoints,
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| 358 | base[last]->points, base[last]->npoints,
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| 359 | &in, &nin, &out, &nout);
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| 360 |
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| 361 | crFree(in);
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| 362 |
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| 363 | for (a=0; a<base[last]->npoints; a++)
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| 364 | {
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| 365 | if (!nout[a]) continue;
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| 366 |
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| 367 | p = (CRPoly *)crAlloc(sizeof(CRPoly));
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| 368 | p->npoints = nout[a];
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| 369 | p->points = out[a];
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| 370 | p->next = diff;
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| 371 | diff = p;
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| 372 | }
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| 373 |
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| 374 | intr = intr->next;
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| 375 | }
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| 376 |
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| 377 | *head = diff;
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| 378 | }
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| 379 |
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| 380 | }
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| 381 |
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| 382 | /*
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| 383 | * Here we generate all valid bitmaps to represent union/difference
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| 384 | * combinations. Each bitmap is N elements long, where N is the
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| 385 | * number of polys [quads] that we are testing for overlap
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| 386 | */
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| 387 | static void
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| 388 | __generate_masks(int n, int ***mask, int *nmasks)
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| 389 | {
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| 390 | int a, b, c, d, e;
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| 391 | int i, idx, isec_size, add;
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| 392 |
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| 393 | *mask = (int **)crAlloc((unsigned int)pow(2, n)*sizeof(int));
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| 394 | for (a=0; a<pow(2, n); a++)
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| 395 | (*mask)[a] = (int *)crAlloc(n*sizeof(int));
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| 396 |
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| 397 | /* compute combinations */
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| 398 | idx = 0;
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| 399 | for (isec_size=1; isec_size<n; isec_size++)
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| 400 | {
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| 401 | for (a=0; a<n; a++)
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| 402 | {
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| 403 | for (b=a+1; b<n; b++)
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| 404 | {
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| 405 | crMemset((*mask)[idx], 0, n*sizeof(int));
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| 406 | (*mask)[idx][a] = 1;
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| 407 |
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| 408 | add = 1;
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| 409 | for (c=0; c<isec_size; c++)
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| 410 | {
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| 411 | i = (b+c) % n;
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| 412 | if (i == a) add = 0;
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| 413 |
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| 414 | (*mask)[idx][i] = 1;
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| 415 | }
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| 416 |
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| 417 | /* dup check */
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| 418 | if ((add) && (idx))
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| 419 | {
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| 420 | for (d=0; d<idx; d++)
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| 421 | {
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| 422 | add = 0;
|
|---|
| 423 | for (e=0; e<n; e++)
|
|---|
| 424 | {
|
|---|
| 425 | if ((*mask)[idx][e] != (*mask)[d][e])
|
|---|
| 426 | add = 1;
|
|---|
| 427 | }
|
|---|
| 428 |
|
|---|
| 429 | if (!add)
|
|---|
| 430 | break;
|
|---|
| 431 | }
|
|---|
| 432 | }
|
|---|
| 433 |
|
|---|
| 434 | if (add)
|
|---|
| 435 | idx++;
|
|---|
| 436 | }
|
|---|
| 437 | }
|
|---|
| 438 | }
|
|---|
| 439 |
|
|---|
| 440 | *nmasks = idx;
|
|---|
| 441 | }
|
|---|
| 442 |
|
|---|
| 443 | /*
|
|---|
| 444 | * To compute the overlap between a series of quads (This should work
|
|---|
| 445 | * for n-gons, but we'll only need quads..), first generate a series of
|
|---|
| 446 | * bitmaps that represent which elements to union together, and which
|
|---|
| 447 | * to difference. This goes into 'mask'. We then evaluate each bitmap with
|
|---|
| 448 | * Sutherland-Hodgman clipping to find the interior (union) and exterior
|
|---|
| 449 | * (difference) regions.
|
|---|
| 450 | *
|
|---|
| 451 | * In the map, 1 == union, 0 == difference
|
|---|
| 452 | *
|
|---|
| 453 | * (*res)[a] is the head of a poly list for all the polys that convert
|
|---|
| 454 | * regions of overlap between a+1 polys ((*res)[0] == NULL)
|
|---|
| 455 | */
|
|---|
| 456 | void
|
|---|
| 457 | crComputeOverlapGeom(double *quads, int nquad, CRPoly ***res)
|
|---|
| 458 | {
|
|---|
| 459 | int a, b, idx, isec_size, **mask;
|
|---|
| 460 | CRPoly *p, *next, **base;
|
|---|
| 461 |
|
|---|
| 462 | base = (CRPoly **)crAlloc(nquad*sizeof(CRPoly *));
|
|---|
| 463 | for (a=0; a<nquad; a++)
|
|---|
| 464 | {
|
|---|
| 465 | p = (CRPoly *)crAlloc(sizeof(CRPoly));
|
|---|
| 466 | p->npoints = 4;
|
|---|
| 467 | p->points = (double *)crAlloc(8*sizeof(double));
|
|---|
| 468 | for (b=0; b<8; b++)
|
|---|
| 469 | {
|
|---|
| 470 | p->points[b] = quads[8*a+b];
|
|---|
| 471 | }
|
|---|
| 472 | p->next = NULL;
|
|---|
| 473 | base[a] = p;
|
|---|
| 474 | }
|
|---|
| 475 |
|
|---|
| 476 | *res = (CRPoly **)crAlloc(nquad*sizeof(CRPoly *));
|
|---|
| 477 | for (a=0; a<nquad; a++)
|
|---|
| 478 | (*res)[a] = NULL;
|
|---|
| 479 |
|
|---|
| 480 | __generate_masks(nquad, &mask, &idx);
|
|---|
| 481 |
|
|---|
| 482 | for (a=0; a<idx; a++)
|
|---|
| 483 | {
|
|---|
| 484 | isec_size = 0;
|
|---|
| 485 | for (b=0; b<nquad; b++)
|
|---|
| 486 | if (mask[a][b]) isec_size++;
|
|---|
| 487 | isec_size--;
|
|---|
| 488 |
|
|---|
| 489 | __execute_combination(base, nquad, mask[a], &p);
|
|---|
| 490 |
|
|---|
| 491 | while (p)
|
|---|
| 492 | {
|
|---|
| 493 | next = p->next;
|
|---|
| 494 |
|
|---|
| 495 | p->next = (*res)[isec_size];
|
|---|
| 496 | (*res)[isec_size] = p;
|
|---|
| 497 |
|
|---|
| 498 | p = next;
|
|---|
| 499 | }
|
|---|
| 500 | }
|
|---|
| 501 |
|
|---|
| 502 | for (a=0; a<nquad; a++)
|
|---|
| 503 | {
|
|---|
| 504 | crFree(base[a]->points);
|
|---|
| 505 | crFree(base[a]);
|
|---|
| 506 | }
|
|---|
| 507 | crFree(base);
|
|---|
| 508 |
|
|---|
| 509 | }
|
|---|
| 510 |
|
|---|
| 511 | /*
|
|---|
| 512 | * This is similar to ComputeOverlapGeom above, but for "knockout"
|
|---|
| 513 | * edge blending.
|
|---|
| 514 | *
|
|---|
| 515 | * my_quad_idx is an index of quads indicating which display tile
|
|---|
| 516 | * we are computing geometry for. From this, we either generate
|
|---|
| 517 | * geometry, or not, such that all geometry can be drawn in black
|
|---|
| 518 | * and only one tile will show through the blend as non-black.
|
|---|
| 519 | *
|
|---|
| 520 | * To add a combination to our set of geom, we must test that:
|
|---|
| 521 | * + mask[a][my_quad_idx] is set
|
|---|
| 522 | * + mask[a][my_quad_idx] is not the first element set in
|
|---|
| 523 | * mask[a].
|
|---|
| 524 | * If these conditions hold, execute mask[a] and draw the resulting
|
|---|
| 525 | * geometry in black
|
|---|
| 526 | *
|
|---|
| 527 | * Unlike ComputeOverlapGeom, res is just a list of polys to draw in black
|
|---|
| 528 | */
|
|---|
| 529 | void
|
|---|
| 530 | crComputeKnockoutGeom(double *quads, int nquad, int my_quad_idx, CRPoly **res)
|
|---|
| 531 | {
|
|---|
| 532 | int a, b, idx, first, **mask;
|
|---|
| 533 | CRPoly *p, *next, **base;
|
|---|
| 534 |
|
|---|
| 535 | base = (CRPoly **) crAlloc(nquad*sizeof(CRPoly *));
|
|---|
| 536 | for (a=0; a<nquad; a++)
|
|---|
| 537 | {
|
|---|
| 538 | p = (CRPoly *) crAlloc(sizeof(CRPoly));
|
|---|
| 539 | p->npoints = 4;
|
|---|
| 540 | p->points = (double *) crAlloc(8*sizeof(double));
|
|---|
| 541 | for (b=0; b<8; b++)
|
|---|
| 542 | {
|
|---|
| 543 | p->points[b] = quads[8*a+b];
|
|---|
| 544 | }
|
|---|
| 545 | p->next = NULL;
|
|---|
| 546 | base[a] = p;
|
|---|
| 547 | }
|
|---|
| 548 |
|
|---|
| 549 | (*res) = NULL;
|
|---|
| 550 |
|
|---|
| 551 | __generate_masks(nquad, &mask, &idx);
|
|---|
| 552 |
|
|---|
| 553 | for (a=0; a<idx; a++)
|
|---|
| 554 | {
|
|---|
| 555 | /* test for above conditions */
|
|---|
| 556 | if (!mask[a][my_quad_idx]) continue;
|
|---|
| 557 |
|
|---|
| 558 | first = -1;
|
|---|
| 559 | for (b=0; b<nquad; b++)
|
|---|
| 560 | if (mask[a][b])
|
|---|
| 561 | {
|
|---|
| 562 | first = b;
|
|---|
| 563 | break;
|
|---|
| 564 | }
|
|---|
| 565 | if (first == my_quad_idx) continue;
|
|---|
| 566 |
|
|---|
| 567 |
|
|---|
| 568 | __execute_combination(base, nquad, mask[a], &p);
|
|---|
| 569 |
|
|---|
| 570 | while (p)
|
|---|
| 571 | {
|
|---|
| 572 | next = p->next;
|
|---|
| 573 |
|
|---|
| 574 | p->next = *res;
|
|---|
| 575 | *res = p;
|
|---|
| 576 |
|
|---|
| 577 | p = next;
|
|---|
| 578 | }
|
|---|
| 579 | }
|
|---|
| 580 |
|
|---|
| 581 | for (a=0; a<nquad; a++)
|
|---|
| 582 | {
|
|---|
| 583 | crFree(base[a]->points);
|
|---|
| 584 | crFree(base[a]);
|
|---|
| 585 | }
|
|---|
| 586 | crFree(base);
|
|---|
| 587 | }
|
|---|
