1 | |
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2 | /*** GEOMETRY.C ***/ |
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3 | |
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4 | #include <math.h> |
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5 | #include "vdefs.h" |
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6 | |
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7 | float deltax, deltay ; |
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8 | int nedges, sqrt_nsites, nvertices ; |
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9 | Freelist efl ; |
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10 | |
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11 | void |
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12 | geominit(void) |
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13 | { |
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14 | freeinit(&efl, sizeof(Edge)) ; |
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15 | nvertices = nedges = 0 ; |
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16 | sqrt_nsites = sqrt(nsites+4) ; |
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17 | deltay = ymax - ymin ; |
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18 | deltax = xmax - xmin ; |
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19 | } |
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20 | |
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21 | Edge * |
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22 | bisect(Site * s1, Site * s2) |
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23 | { |
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24 | float dx, dy, adx, ady ; |
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25 | Edge * newedge ; |
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26 | |
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27 | newedge = (Edge *)getfree(&efl) ; |
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28 | newedge->reg[0] = s1 ; |
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29 | newedge->reg[1] = s2 ; |
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30 | ref(s1) ; |
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31 | ref(s2) ; |
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32 | newedge->ep[0] = newedge->ep[1] = (Site *)NULL ; |
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33 | dx = s2->coord.x - s1->coord.x ; |
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34 | dy = s2->coord.y - s1->coord.y ; |
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35 | adx = dx>0 ? dx : -dx ; |
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36 | ady = dy>0 ? dy : -dy ; |
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37 | newedge->c = s1->coord.x * dx + s1->coord.y * dy + (dx*dx + |
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38 | dy*dy) * 0.5 ; |
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39 | if (adx > ady) |
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40 | { |
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41 | newedge->a = 1.0 ; |
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42 | newedge->b = dy/dx ; |
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43 | newedge->c /= dx ; |
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44 | } |
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45 | else |
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46 | { |
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47 | newedge->b = 1.0 ; |
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48 | newedge->a = dx/dy ; |
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49 | newedge->c /= dy ; |
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50 | } |
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51 | newedge->edgenbr = nedges ; |
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52 | out_bisector(newedge) ; |
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53 | nedges++ ; |
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54 | return (newedge) ; |
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55 | } |
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56 | |
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57 | Site * |
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58 | intersect(Halfedge * el1, Halfedge * el2) |
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59 | { |
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60 | Edge * e1, * e2, * e ; |
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61 | Halfedge * el ; |
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62 | float d, xint, yint ; |
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63 | int right_of_site ; |
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64 | Site * v ; |
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65 | |
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66 | e1 = el1->ELedge ; |
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67 | e2 = el2->ELedge ; |
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68 | if ((e1 == (Edge*)NULL) || (e2 == (Edge*)NULL)) |
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69 | { |
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70 | return ((Site *)NULL) ; |
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71 | } |
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72 | if (e1->reg[1] == e2->reg[1]) |
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73 | { |
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74 | return ((Site *)NULL) ; |
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75 | } |
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76 | d = (e1->a * e2->b) - (e1->b * e2->a) ; |
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77 | if ((-1.0e-10 < d) && (d < 1.0e-10)) |
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78 | { |
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79 | return ((Site *)NULL) ; |
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80 | } |
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81 | xint = (e1->c * e2->b - e2->c * e1->b) / d ; |
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82 | yint = (e2->c * e1->a - e1->c * e2->a) / d ; |
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83 | if ((e1->reg[1]->coord.y < e2->reg[1]->coord.y) || |
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84 | (e1->reg[1]->coord.y == e2->reg[1]->coord.y && |
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85 | e1->reg[1]->coord.x < e2->reg[1]->coord.x)) |
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86 | { |
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87 | el = el1 ; |
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88 | e = e1 ; |
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89 | } |
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90 | else |
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91 | { |
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92 | el = el2 ; |
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93 | e = e2 ; |
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94 | } |
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95 | right_of_site = (xint >= e->reg[1]->coord.x) ; |
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96 | if ((right_of_site && (el->ELpm == le)) || |
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97 | (!right_of_site && (el->ELpm == re))) |
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98 | { |
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99 | return ((Site *)NULL) ; |
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100 | } |
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101 | v = (Site *)getfree(&sfl) ; |
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102 | v->refcnt = 0 ; |
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103 | v->coord.x = xint ; |
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104 | v->coord.y = yint ; |
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105 | return (v) ; |
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106 | } |
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107 | |
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108 | /*** returns 1 if p is to right of halfedge e ***/ |
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109 | |
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110 | int |
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111 | right_of(Halfedge * el, Point * p) |
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112 | { |
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113 | Edge * e ; |
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114 | Site * topsite ; |
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115 | int right_of_site, above, fast ; |
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116 | float dxp, dyp, dxs, t1, t2, t3, yl ; |
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117 | |
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118 | e = el->ELedge ; |
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119 | topsite = e->reg[1] ; |
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120 | right_of_site = (p->x > topsite->coord.x) ; |
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121 | if (right_of_site && (el->ELpm == le)) |
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122 | { |
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123 | return (1) ; |
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124 | } |
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125 | if(!right_of_site && (el->ELpm == re)) |
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126 | { |
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127 | return (0) ; |
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128 | } |
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129 | if (e->a == 1.0) |
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130 | { |
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131 | dyp = p->y - topsite->coord.y ; |
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132 | dxp = p->x - topsite->coord.x ; |
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133 | fast = 0 ; |
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134 | if ((!right_of_site & (e->b < 0.0)) || |
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135 | (right_of_site & (e->b >= 0.0))) |
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136 | { |
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137 | fast = above = (dyp >= e->b*dxp) ; |
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138 | } |
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139 | else |
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140 | { |
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141 | above = ((p->x + p->y * e->b) > (e->c)) ; |
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142 | if (e->b < 0.0) |
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143 | { |
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144 | above = !above ; |
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145 | } |
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146 | if (!above) |
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147 | { |
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148 | fast = 1 ; |
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149 | } |
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150 | } |
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151 | if (!fast) |
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152 | { |
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153 | dxs = topsite->coord.x - (e->reg[0])->coord.x ; |
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154 | above = (e->b * (dxp*dxp - dyp*dyp)) |
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155 | < |
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156 | (dxs * dyp * (1.0 + 2.0 * dxp / |
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157 | dxs + e->b * e->b)) ; |
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158 | if (e->b < 0.0) |
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159 | { |
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160 | above = !above ; |
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161 | } |
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162 | } |
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163 | } |
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164 | else /*** e->b == 1.0 ***/ |
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165 | { |
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166 | yl = e->c - e->a * p->x ; |
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167 | t1 = p->y - yl ; |
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168 | t2 = p->x - topsite->coord.x ; |
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169 | t3 = yl - topsite->coord.y ; |
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170 | above = ((t1*t1) > ((t2 * t2) + (t3 * t3))) ; |
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171 | } |
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172 | return (el->ELpm == le ? above : !above) ; |
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173 | } |
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174 | |
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175 | void |
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176 | endpoint(Edge * e, int lr, Site * s) |
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177 | { |
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178 | e->ep[lr] = s ; |
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179 | ref(s) ; |
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180 | if (e->ep[re-lr] == (Site *)NULL) |
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181 | { |
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182 | return ; |
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183 | } |
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184 | out_ep(e) ; |
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185 | deref(e->reg[le]) ; |
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186 | deref(e->reg[re]) ; |
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187 | makefree((Freenode *)e, (Freelist *) &efl) ; |
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188 | } |
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189 | |
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190 | float |
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191 | dist(Site * s, Site * t) |
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192 | { |
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193 | float dx,dy ; |
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194 | |
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195 | dx = s->coord.x - t->coord.x ; |
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196 | dy = s->coord.y - t->coord.y ; |
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197 | return (sqrt(dx*dx + dy*dy)) ; |
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198 | } |
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199 | |
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200 | void |
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201 | makevertex(Site * v) |
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202 | { |
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203 | v->sitenbr = nvertices++ ; |
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204 | out_vertex(v) ; |
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205 | } |
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206 | |
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207 | void |
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208 | deref(Site * v) |
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209 | { |
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210 | if (--(v->refcnt) == 0 ) |
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211 | { |
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212 | makefree((Freenode *)v, (Freelist *)&sfl) ; |
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213 | } |
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214 | } |
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215 | |
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216 | void |
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217 | ref(Site * v) |
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218 | { |
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219 | ++(v->refcnt) ; |
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220 | } |
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221 | |
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