[37] | 1 | /* |
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| 2 | |
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| 3 | Homan Igehy |
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| 4 | |
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| 5 | Computer Graphics Laboratory |
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| 6 | Stanford University |
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| 7 | |
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| 8 | --------------------------------------------------------------------- |
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| 9 | |
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| 10 | Copyright (1997) The Board of Trustees of the Leland Stanford Junior |
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| 11 | University. Except for commercial resale, lease, license or other |
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| 12 | commercial transactions, permission is hereby given to use, copy, |
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| 13 | modify this software for academic purposes only. No part of this |
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| 14 | software or any derivatives thereof may be used in the production of |
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| 15 | computer models for resale or for use in a commercial |
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| 16 | product. STANFORD MAKES NO REPRESENTATIONS OR WARRANTIES OF ANY KIND |
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| 17 | CONCERNING THIS SOFTWARE. No support is implied or provided. |
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| 18 | |
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| 19 | */ |
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| 20 | |
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| 21 | |
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| 22 | /* |
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| 23 | * sl_triangle.C |
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| 24 | * |
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| 25 | */ |
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| 26 | |
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| 27 | #ifndef SL_TRIANGLE_C |
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| 28 | #define SL_TRIANGLE_C |
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| 29 | |
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| 30 | #include <assert.h> |
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| 31 | #include <iostream> |
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| 32 | |
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| 33 | #include "sl_vertex.H" |
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| 34 | #include "sl_texture.H" |
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| 35 | #include "sl_export.H" |
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| 36 | #include "sl_hack.H" |
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| 37 | #include "sl_common.H" |
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| 38 | |
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| 39 | |
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| 40 | #define SL_REGULAR 0 |
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| 41 | #define SL_DEGENERATE 1 |
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| 42 | #define SL_TOP_HORIZONTAL 2 |
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| 43 | #define SL_BOT_HORIZONTAL 4 |
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| 44 | |
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| 45 | |
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| 46 | typedef struct SL_Triangle { |
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| 47 | Real fe_curx, fe_dxdy; |
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| 48 | Real se_curx, se_dxdy; |
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| 49 | Real me_curx, me_dxdy; |
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| 50 | IN_DeclareArgs(cur) |
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| 51 | IN_DeclareArgs(ddy) |
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| 52 | IN_DeclareArgs(ddx) |
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| 53 | Integer y_lo, y_mid, y_hi; |
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| 54 | #ifdef LevelOfDetail |
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| 55 | Integer x_lo, x_mid, x_hi; |
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| 56 | #endif |
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| 57 | } SL_Triangle; |
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| 58 | |
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| 59 | |
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| 60 | |
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| 61 | #define VSWAP(a, b) { IS_Vertex *tmp = a; a = b; b = tmp; } |
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| 62 | #define ISWAP(a, b) { Integer tmp = a; a = b; b = tmp; } |
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| 63 | |
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| 64 | |
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| 65 | #define SetDdyCurDdx(i) \ |
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| 66 | lo = IN_IndexP(v_lo, i); \ |
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| 67 | ddy = (IN_IndexP(v_hi, i) - lo) * inv_ydiff_full; \ |
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| 68 | mid = IN_IndexP(v_mid, i); \ |
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| 69 | IN_Index(tri->ddx, i) = (((mid - lo) * inv_ydiff_slope) - ddy)*inv_xdiff; \ |
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| 70 | IN_Index(tri->cur, i) = lo + ddy * yfrac_lo; \ |
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| 71 | IN_Index(tri->ddy, i) = ddy; \ |
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| 72 | |
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| 73 | |
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| 74 | |
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| 75 | #define SetDdyCurDdx_BotHor(i) \ |
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| 76 | hi = IN_IndexP(v_hi, i); \ |
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| 77 | lo = IN_IndexP(v_lo, i); \ |
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| 78 | ddy = (hi - lo) * inv_ydiff_full; \ |
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| 79 | mid = IN_IndexP(v_mid, i); \ |
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| 80 | IN_Index(tri->ddx, i) = (((hi - mid) * inv_ydiff_slope) - ddy)*inv_xdiff; \ |
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| 81 | IN_Index(tri->cur, i) = lo + ddy * yfrac_lo; \ |
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| 82 | IN_Index(tri->ddy, i) = ddy; \ |
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| 83 | |
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| 84 | |
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| 85 | static inline Integer8 |
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| 86 | SL_3VertexTo3Edge(SL_Triangle *tri, |
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| 87 | IS_Vertex *v_lo, |
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| 88 | IS_Vertex *v_mid, |
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| 89 | IS_Vertex *v_hi) |
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| 90 | { |
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| 91 | |
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| 92 | Integer y_lo = CeilR2I(v_lo->y); |
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| 93 | Integer y_mid = CeilR2I(v_mid->y); |
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| 94 | Integer y_hi = CeilR2I(v_hi->y); |
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| 95 | |
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| 96 | if (y_lo > y_mid) { |
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| 97 | VSWAP(v_lo, v_mid); |
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| 98 | ISWAP(y_lo, y_mid); |
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| 99 | } |
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| 100 | |
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| 101 | if (y_mid > y_hi) { |
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| 102 | VSWAP(v_mid, v_hi); |
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| 103 | ISWAP(y_mid, y_hi); |
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| 104 | } |
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| 105 | |
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| 106 | if (y_lo > y_mid) { |
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| 107 | VSWAP(v_lo, v_mid); |
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| 108 | ISWAP(y_lo, y_mid); |
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| 109 | } |
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| 110 | |
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| 111 | tri->y_lo = y_lo; |
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| 112 | tri->y_hi = y_hi; |
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| 113 | tri->y_mid = y_mid; |
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| 114 | |
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| 115 | |
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| 116 | |
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| 117 | #ifdef LevelOfDetail |
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| 118 | |
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| 119 | Integer x_lo = CeilR2I(v_lo->x); |
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| 120 | Integer x_mid = CeilR2I(v_mid->x); |
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| 121 | Integer x_hi = CeilR2I(v_hi->x); |
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| 122 | |
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| 123 | if (x_lo > x_mid) { |
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| 124 | ISWAP(x_lo, x_mid); |
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| 125 | } |
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| 126 | |
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| 127 | if (x_mid > x_hi) { |
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| 128 | ISWAP(x_mid, x_hi); |
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| 129 | } |
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| 130 | |
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| 131 | if (x_lo > x_mid) { |
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| 132 | ISWAP(x_lo, x_mid); |
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| 133 | } |
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| 134 | |
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| 135 | tri->x_lo = x_lo; |
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| 136 | tri->x_hi = x_hi; |
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| 137 | tri->x_mid = x_mid; |
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| 138 | |
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| 139 | #endif |
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| 140 | |
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| 141 | |
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| 142 | int type; |
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| 143 | |
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| 144 | if (y_lo == y_hi) { |
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| 145 | return SL_DEGENERATE; |
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| 146 | } |
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| 147 | |
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| 148 | Real inv_ydiff_full = REAL_ONE / (v_hi->y - v_lo->y); |
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| 149 | |
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| 150 | Real yfrac_lo = (Real) y_lo - v_lo->y; |
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| 151 | Real yfrac_mid = (Real) y_mid - v_mid->y; |
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| 152 | |
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| 153 | if (y_lo == y_mid) |
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| 154 | type = SL_BOT_HORIZONTAL; |
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| 155 | else if (y_mid == y_hi) |
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| 156 | type = SL_TOP_HORIZONTAL; |
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| 157 | else |
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| 158 | type = SL_REGULAR; |
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| 159 | |
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| 160 | Real lo, mid, hi, ddy; |
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| 161 | |
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| 162 | lo = v_lo->x; |
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| 163 | ddy = (v_hi->x - lo) * inv_ydiff_full; |
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| 164 | |
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| 165 | Real inv_ydiff_slope; |
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| 166 | if (type == SL_BOT_HORIZONTAL) |
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| 167 | inv_ydiff_slope = REAL_ONE / (v_hi->y - v_mid->y); |
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| 168 | else |
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| 169 | inv_ydiff_slope = REAL_ONE / (v_mid->y - v_lo->y); |
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| 170 | |
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| 171 | tri->fe_curx = lo + ddy * yfrac_lo; |
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| 172 | tri->fe_dxdy = ddy; |
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| 173 | |
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| 174 | |
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| 175 | if (type == SL_BOT_HORIZONTAL) { |
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| 176 | mid = v_mid->x; |
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| 177 | ddy = (v_hi->x - mid) * inv_ydiff_slope; |
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| 178 | |
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| 179 | Real inv_xdiff = REAL_ONE / (ddy - tri->fe_dxdy); |
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| 180 | |
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| 181 | tri->se_curx = mid + ddy * yfrac_mid; |
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| 182 | tri->se_dxdy = ddy; |
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| 183 | |
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| 184 | IN_DoForEach(SetDdyCurDdx_BotHor); |
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| 185 | |
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| 186 | } |
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| 187 | else { |
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| 188 | lo = v_lo->x; |
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| 189 | ddy = (v_mid->x - lo) * inv_ydiff_slope; |
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| 190 | |
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| 191 | Real inv_xdiff = REAL_ONE / (ddy - tri->fe_dxdy); |
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| 192 | |
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| 193 | tri->se_curx = lo + ddy * yfrac_lo; |
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| 194 | tri->se_dxdy = ddy; |
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| 195 | |
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| 196 | IN_DoForEach(SetDdyCurDdx); |
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| 197 | } |
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| 198 | |
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| 199 | |
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| 200 | |
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| 201 | |
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| 202 | if (type == SL_REGULAR) { |
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| 203 | mid = v_mid->x; |
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| 204 | ddy = (v_hi->x - mid) / (v_hi->y - v_mid->y); |
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| 205 | tri->me_curx = mid + ddy * yfrac_mid; |
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| 206 | tri->me_dxdy = ddy; |
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| 207 | } |
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| 208 | |
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| 209 | |
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| 210 | |
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| 211 | |
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| 212 | return type; |
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| 213 | |
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| 214 | } |
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| 215 | |
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| 216 | |
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| 217 | #define MAX(a, b) ((a) > (b) ? (a) : (b)) |
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| 218 | |
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| 219 | #ifdef LevelOfDetail |
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| 220 | |
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| 221 | static inline void |
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| 222 | SL_InitializeNumPars(SL_Triangle *tri, Real *numParXArray, Real *numParYArray) |
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| 223 | { |
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| 224 | Real dudy = tri->ddyU - tri->ddxU * tri->fe_dxdy; |
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| 225 | Real dvdy = tri->ddyV - tri->ddxV * tri->fe_dxdy; |
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| 226 | Real dwdy = tri->ddyW - tri->ddxW * tri->fe_dxdy; |
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| 227 | |
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| 228 | Real x_frac = ((Real) tri->x_lo) - tri->fe_curx; |
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| 229 | |
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| 230 | Real u_slope = tri->ddxU * dwdy - dudy * tri->ddxW; |
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| 231 | Real v_slope = tri->ddxV * dwdy - dvdy * tri->ddxW; |
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| 232 | |
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| 233 | Real uy_cur = (tri->curW * dudy - tri->curU * dwdy) - u_slope * x_frac; |
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| 234 | Real vy_cur = (tri->curW * dvdy - tri->curV * dwdy) - v_slope * x_frac; |
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| 235 | |
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| 236 | Real ux_cur = tri->curW * tri->ddxU - tri->curU * tri->ddxW; |
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| 237 | Real vx_cur = tri->curW * tri->ddxV - tri->curV * tri->ddxW; |
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| 238 | |
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| 239 | |
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| 240 | for (int x = tri->x_lo; |
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| 241 | x != tri->x_hi; |
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| 242 | x++, uy_cur -= u_slope, vy_cur -= v_slope) |
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| 243 | numParYArray[x] = MAX(Abs(uy_cur), Abs(vy_cur)); |
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| 244 | |
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| 245 | for (int y = tri->y_lo; |
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| 246 | y != tri->y_hi; |
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| 247 | y++, ux_cur += u_slope, vx_cur += v_slope) |
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| 248 | numParXArray[y] = MAX(Abs(ux_cur), Abs(vx_cur)); |
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| 249 | |
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| 250 | |
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| 251 | } |
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| 252 | |
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| 253 | #endif |
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| 254 | |
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| 255 | |
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| 256 | #define CopyAll(i) { IN_Index(cur, i) = IN_Index(tri->cur, i); \ |
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| 257 | IN_Index(ddy, i) = IN_Index(tri->ddy, i); \ |
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| 258 | IN_Index(ddx, i) = IN_Index(tri->ddx, i); } |
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| 259 | |
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| 260 | #define IncrementY(i) { IN_Index(cur, i) += IN_Index(ddy, i); } |
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| 261 | |
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| 262 | |
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| 263 | static inline void |
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| 264 | SL_ScanConvertLR(SL_Triangle *tri, |
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| 265 | const IS_CAttr *cattr, |
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| 266 | const FB_Buffer *buffer) |
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| 267 | { |
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| 268 | #ifdef LevelOfDetail |
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| 269 | |
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| 270 | Real numParXArray[MAX_SCREEN_DIMENSION]; |
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| 271 | Real numParYArray[MAX_SCREEN_DIMENSION]; |
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| 272 | |
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| 273 | SL_InitializeNumPars(tri, numParXArray, numParYArray); |
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| 274 | |
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| 275 | #endif |
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| 276 | |
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| 277 | Integer cur_y = tri->y_lo; |
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| 278 | Integer width = buffer->width; |
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| 279 | Integer offset = cur_y * width; |
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| 280 | |
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| 281 | #ifdef LevelOfDetail |
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| 282 | Real *numParXPtr = numParXArray + cur_y; |
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| 283 | #endif |
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| 284 | |
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| 285 | Real lx = tri->fe_curx; |
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| 286 | Real dlx = tri->fe_dxdy; |
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| 287 | |
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| 288 | IN_DeclareArgs(cur); |
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| 289 | IN_DeclareArgs(ddy); |
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| 290 | IN_DeclareArgs(ddx); |
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| 291 | IN_DoForEach(CopyAll); |
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| 292 | |
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| 293 | Real rx = tri->se_curx; |
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| 294 | Real drx = tri->se_dxdy; |
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| 295 | |
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| 296 | while (cur_y != tri->y_mid) { |
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| 297 | cur_y++; |
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| 298 | SL_ScanXLeftToRight(lx, rx, |
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| 299 | IN_ListArgs(cur) |
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| 300 | IN_ListArgs(ddx) |
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| 301 | CA_ListArgs(cattr->) |
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| 302 | #ifdef LevelOfDetail |
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| 303 | *numParXPtr, numParYArray, |
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| 304 | #endif |
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| 305 | buffer, offset); |
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| 306 | rx += drx; |
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| 307 | lx += dlx; |
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| 308 | offset += width; |
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| 309 | #ifdef LevelOfDetail |
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| 310 | numParXPtr++; |
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| 311 | #endif |
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| 312 | IN_DoForEach(IncrementY); |
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| 313 | } |
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| 314 | |
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| 315 | rx = tri->me_curx; |
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| 316 | drx = tri->me_dxdy; |
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| 317 | |
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| 318 | while (cur_y != tri->y_hi) { |
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| 319 | cur_y++; |
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| 320 | SL_ScanXLeftToRight(lx, rx, |
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| 321 | IN_ListArgs(cur) |
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| 322 | IN_ListArgs(ddx) |
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| 323 | CA_ListArgs(cattr->) |
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| 324 | #ifdef LevelOfDetail |
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| 325 | *numParXPtr, numParYArray, |
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| 326 | #endif |
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| 327 | buffer, offset); |
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| 328 | rx += drx; |
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| 329 | lx += dlx; |
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| 330 | offset += width; |
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| 331 | #ifdef LevelOfDetail |
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| 332 | numParXPtr++; |
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| 333 | #endif |
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| 334 | IN_DoForEach(IncrementY); |
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| 335 | } |
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| 336 | } |
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| 337 | |
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| 338 | |
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| 339 | static inline void |
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| 340 | SL_ScanConvertRL(SL_Triangle *tri, |
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| 341 | const IS_CAttr *cattr, |
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| 342 | const FB_Buffer *buffer) |
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| 343 | { |
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| 344 | #ifdef LevelOfDetail |
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| 345 | |
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| 346 | Real numParXArray[MAX_SCREEN_DIMENSION]; |
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| 347 | Real numParYArray[MAX_SCREEN_DIMENSION]; |
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| 348 | |
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| 349 | SL_InitializeNumPars(tri, numParXArray, numParYArray); |
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| 350 | |
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| 351 | #endif |
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| 352 | |
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| 353 | Integer cur_y = tri->y_lo; |
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| 354 | Integer width = buffer->width; |
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| 355 | Integer offset = cur_y * width; |
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| 356 | |
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| 357 | #ifdef LevelOfDetail |
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| 358 | Real *numParXPtr = numParXArray + cur_y; |
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| 359 | #endif |
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| 360 | |
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| 361 | Real rx = tri->fe_curx; |
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| 362 | Real drx = tri->fe_dxdy; |
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| 363 | |
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| 364 | IN_DeclareArgs(cur); |
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| 365 | IN_DeclareArgs(ddy); |
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| 366 | IN_DeclareArgs(ddx); |
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| 367 | IN_DoForEach(CopyAll); |
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| 368 | |
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| 369 | Real lx = tri->se_curx; |
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| 370 | Real dlx = tri->se_dxdy; |
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| 371 | |
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| 372 | while (cur_y != tri->y_mid) { |
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| 373 | cur_y++; |
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| 374 | SL_ScanXRightToLeft(lx, rx, |
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| 375 | IN_ListArgs(cur) |
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| 376 | IN_ListArgs(ddx) |
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| 377 | CA_ListArgs(cattr->) |
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| 378 | #ifdef LevelOfDetail |
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| 379 | *numParXPtr, numParYArray, |
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| 380 | #endif |
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| 381 | buffer, offset); |
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| 382 | rx += drx; |
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| 383 | lx += dlx; |
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| 384 | offset += width; |
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| 385 | #ifdef LevelOfDetail |
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| 386 | numParXPtr++; |
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| 387 | #endif |
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| 388 | IN_DoForEach(IncrementY); |
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| 389 | } |
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| 390 | |
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| 391 | lx = tri->me_curx; |
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| 392 | dlx = tri->me_dxdy; |
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| 393 | |
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| 394 | while (cur_y != tri->y_hi) { |
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| 395 | cur_y++; |
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| 396 | SL_ScanXRightToLeft(lx, rx, |
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| 397 | IN_ListArgs(cur) |
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| 398 | IN_ListArgs(ddx) |
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| 399 | CA_ListArgs(cattr->) |
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| 400 | #ifdef LevelOfDetail |
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| 401 | *numParXPtr, numParYArray, |
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| 402 | #endif |
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| 403 | buffer, offset); |
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| 404 | rx += drx; |
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| 405 | lx += dlx; |
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| 406 | offset += width; |
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| 407 | #ifdef LevelOfDetail |
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| 408 | numParXPtr++; |
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| 409 | #endif |
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| 410 | IN_DoForEach(IncrementY); |
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| 411 | } |
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| 412 | } |
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| 413 | |
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| 414 | |
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| 415 | |
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| 416 | void |
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| 417 | #ifdef SampleCalc_Dda |
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| 418 | SL_SCTriangle_DDA |
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| 419 | #endif |
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| 420 | #ifdef SampleCalc_Ddx |
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| 421 | SL_SCTriangle_DDX |
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| 422 | #endif |
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| 423 | ( |
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| 424 | IS_Vertex *v_lo, |
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| 425 | IS_Vertex *v_mid, |
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| 426 | IS_Vertex *v_hi, |
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| 427 | IS_CAttr *cattr, |
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| 428 | FB_Buffer *buffer |
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| 429 | ) |
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| 430 | { |
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| 431 | SL_Triangle tri; |
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| 432 | |
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| 433 | int type = SL_3VertexTo3Edge(&tri, v_lo, v_mid, v_hi); |
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| 434 | |
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| 435 | if (type == SL_DEGENERATE) |
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| 436 | return; |
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| 437 | |
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| 438 | if (type == SL_BOT_HORIZONTAL) |
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| 439 | tri.y_mid = tri.y_hi; |
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| 440 | |
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| 441 | if ((tri.fe_dxdy <= tri.se_dxdy) ^ (type == SL_BOT_HORIZONTAL)) { |
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| 442 | SL_ScanConvertLR(&tri, cattr, buffer); |
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| 443 | } |
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| 444 | else { |
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| 445 | SL_ScanConvertRL(&tri, cattr, buffer); |
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| 446 | } |
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| 447 | |
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| 448 | } |
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| 449 | |
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| 450 | |
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| 451 | |
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| 452 | #endif /* SL_TRIANGLE_C */ |
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