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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