2 #define _USE_MATH_DEFINES
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4 #include "glmatrix.h"
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7 #define M_PI 3.141592653589793
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10 #define MMODE_IDX(x) ((x) - GL_MODELVIEW)
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11 #define MAT_STACK_SIZE 32
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12 #define MAT_IDENT {1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1, 0, 0, 0, 0, 1}
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14 static int mm_idx = 0;
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15 static float mat_stack[3][MAT_STACK_SIZE][16] = {{MAT_IDENT}, {MAT_IDENT}, {MAT_IDENT}};
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16 static int stack_top[3];
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18 void gl_matrix_mode(int mm)
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20 mm_idx = MMODE_IDX(mm);
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23 void gl_push_matrix(void)
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25 int top = stack_top[mm_idx];
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27 memcpy(mat_stack[mm_idx][top + 1], mat_stack[mm_idx][top], 16 * sizeof(float));
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28 stack_top[mm_idx]++;
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31 void gl_pop_matrix(void)
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33 stack_top[mm_idx]--;
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36 void gl_load_identity(void)
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38 static const float idmat[] = MAT_IDENT;
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39 int top = stack_top[mm_idx];
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40 float *mat = mat_stack[mm_idx][top];
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42 memcpy(mat, idmat, sizeof idmat);
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45 void gl_load_matrixf(const float *m)
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47 int top = stack_top[mm_idx];
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48 float *mat = mat_stack[mm_idx][top];
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50 memcpy(mat, m, 16 * sizeof *mat);
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53 #define M4(i, j) ((i << 2) + j)
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55 void gl_mult_matrixf(const float *m2)
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58 int top = stack_top[mm_idx];
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59 float *m1 = mat_stack[mm_idx][top];
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62 for(i=0; i<4; i++) {
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63 for(j=0; j<4; j++) {
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64 res[M4(i,j)] = m1[M4(i,0)] * m2[M4(0,j)] +
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65 m1[M4(i,1)] * m2[M4(1,j)] +
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66 m1[M4(i,2)] * m2[M4(2,j)] +
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67 m1[M4(i,3)] * m2[M4(3,j)];
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71 memcpy(m1, res, sizeof res);
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74 void gl_translatef(float x, float y, float z)
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76 float mat[] = MAT_IDENT;
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82 gl_mult_matrixf(mat);
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85 void gl_rotatef(float angle, float x, float y, float z)
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87 float mat[] = MAT_IDENT;
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89 float angle_rad = (float)M_PI * angle / 180.f;
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90 float sina = (float)sin(angle_rad);
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91 float cosa = (float)cos(angle_rad);
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92 float one_minus_cosa = 1.f - cosa;
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97 mat[0] = nxsq + (1.f - nxsq) * cosa;
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98 mat[4] = x * y * one_minus_cosa - z * sina;
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99 mat[8] = x * z * one_minus_cosa + y * sina;
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100 mat[1] = x * y * one_minus_cosa + z * sina;
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101 mat[5] = nysq + (1.f - nysq) * cosa;
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102 mat[9] = y * z * one_minus_cosa - x * sina;
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103 mat[2] = x * z * one_minus_cosa - y * sina;
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104 mat[6] = y * z * one_minus_cosa + x * sina;
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105 mat[10] = nzsq + (1.f - nzsq) * cosa;
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107 gl_mult_matrixf(mat);
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110 void gl_scalef(float x, float y, float z)
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112 float mat[] = MAT_IDENT;
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118 gl_mult_matrixf(mat);
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121 void gl_ortho(float left, float right, float bottom, float top, float znear, float zfar)
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123 float mat[] = MAT_IDENT;
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125 float dx = right - left;
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126 float dy = top - bottom;
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127 float dz = zfar - znear;
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129 float tx = -(right + left) / dx;
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130 float ty = -(top + bottom) / dy;
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131 float tz = -(zfar + znear) / dz;
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133 float sx = 2.f / dx;
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134 float sy = 2.f / dy;
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135 float sz = -2.f / dz;
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144 gl_mult_matrixf(mat);
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147 void gl_frustum(float left, float right, float bottom, float top, float znear, float zfar)
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149 float mat[] = MAT_IDENT;
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151 float dx = right - left;
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152 float dy = top - bottom;
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153 float dz = zfar - znear;
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155 float a = (right + left) / dx;
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156 float b = (top + bottom) / dy;
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157 float c = -(zfar + znear) / dz;
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158 float d = -2.f * zfar * znear / dz;
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160 mat[0] = 2.f * znear / dx;
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161 mat[5] = 2.f * znear / dy;
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169 gl_mult_matrixf(mat);
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172 void glu_perspective(float vfov, float aspect, float znear, float zfar)
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174 float vfov_rad = (float)M_PI * vfov / 180.f;
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175 float x = znear * (float)tan(vfov_rad / 2.f);
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176 gl_frustum(-aspect * x, aspect * x, -x, x, znear, zfar);
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179 /* return the matrix (16 elements, 4x4 matrix, row-major order */
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180 float* get_matrix(int mm)
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182 int idx = MMODE_IDX(mm);
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183 int top = stack_top[idx];
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184 return mat_stack[idx][top];
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188 #define M3(i, j) ((i * 3) + j)
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189 static float inv_transpose_result[9];
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191 /* return the inverse transpose of the left-upper 3x3 of a matrix
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192 The returned pointer is only valid until the next time this function is
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193 called, so make a deep copy when you want to keep it around.
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195 float* get_inv_transpose_3x3(int mm)
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197 int idx = MMODE_IDX(mm);
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198 int top = stack_top[idx];
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199 float *m1 = mat_stack[idx][top];
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202 float determinant = +m1[M4(0,0)]*(m1[M4(1,1)]*m1[M4(2,2)]-m1[M4(2,1)]*m1[M4(1,2)])
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203 -m1[M4(0,1)]*(m1[M4(1,0)]*m1[M4(2,2)]-m1[M4(1,2)]*m1[M4(2,0)])
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204 +m1[M4(0,2)]*(m1[M4(1,0)]*m1[M4(2,1)]-m1[M4(1,1)]*m1[M4(2,0)]);
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206 float invdet = 1/determinant;
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208 inv_transpose_result[M3(0,0)] = (m1[M4(1,1)]*m1[M4(2,2)]-m1[M4(2,1)]*m1[M4(1,2)])*invdet;
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209 inv_transpose_result[M3(1,0)] = -(m1[M4(0,1)]*m1[M4(2,2)]-m1[M4(0,2)]*m1[M4(2,1)])*invdet;
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210 inv_transpose_result[M3(2,0)] = (m1[M4(0,1)]*m1[M4(1,2)]-m1[M4(0,2)]*m1[M4(1,1)])*invdet;
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211 inv_transpose_result[M3(0,1)] = -(m1[M4(1,0)]*m1[M4(2,2)]-m1[M4(1,2)]*m1[M4(2,0)])*invdet;
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212 inv_transpose_result[M3(1,1)] = (m1[M4(0,0)]*m1[M4(2,2)]-m1[M4(0,2)]*m1[M4(2,0)])*invdet;
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213 inv_transpose_result[M3(2,1)] = -(m1[M4(0,0)]*m1[M4(1,2)]-m1[M4(1,0)]*m1[M4(0,2)])*invdet;
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214 inv_transpose_result[M3(0,2)] = (m1[M4(1,0)]*m1[M4(2,1)]-m1[M4(2,0)]*m1[M4(1,1)])*invdet;
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215 inv_transpose_result[M3(1,2)] = -(m1[M4(0,0)]*m1[M4(2,1)]-m1[M4(2,0)]*m1[M4(0,1)])*invdet;
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216 inv_transpose_result[M3(2,2)] = (m1[M4(0,0)]*m1[M4(1,1)]-m1[M4(1,0)]*m1[M4(0,1)])*invdet;
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218 return inv_transpose_result;
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