我正在尝试将地图栅格图像渲染为OpenGL中的纹理。原始图像文件像素格式为单个字节，并且其RGB值为256x3字节的色彩映射表（R，G，B）。我可以正确渲染图像，以执行颜色映射并在CPU中生成RGB像素，然后将其作为纹理加载到OpenGL中。但是我想让片段着色器做到这一点。由于我当前使用的是OpenGL ES，因此正在将颜色图加载为256x1 2D纹理（不支持1D）。但是我得到了错误的颜色渲染（全部为红色或某些图像提示全部为红色）。我可以使用非常原始的黑白渲染来分配fragColor = texture（ourTexture，texCoord）.rrr，以便图像纹理加载看起来很好；
这是片段着色器：
#version 300 es
precision mediump float;
in vec2 texCoord;
out vec4 fragColor;
uniform sampler2D ourTexture;
uniform sampler2D colormap;
void main() {
float color =texture(ourTexture, texCoord).r;
fragColor = texture(colormap, vec2(color,0.0));
}
这是颜色图纹理初始化
glGenTextures(1, &render.colormapTexture);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, render.colormapTexture);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB,
256, 1, 0, GL_RGB, GL_UNSIGNED_BYTE, &render.geoData.colormap[0]);
这里是光栅图像初始化：
glGenTextures(1, &cache.cache[i].texture.texID);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, cache.cache[i].texture.texID);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
和像素加载到其他地方
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D, tile->texture->texID);
glTexImage2D(GL_TEXTURE_2D, 0, GL_RED,
tile->texture->width,
tile->texture->height, 0, GL_RED,
GL_UNSIGNED_BYTE,
tile->texture->texData);
这里是绘图代码：
glBindVertexArray(render.grid.terrainGrid[i][j].vao);
glActiveTexture(GL_TEXTURE0);
glBindTexture(GL_TEXTURE_2D,
render.grid.terrainGrid[i][j].texture->texID);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, render.colormapTexture);
glDrawElements(GL_TRIANGLES, 6, GL_UNSIGNED_INT,0);
这是颜色图的格式化输出，因为它被加载为纹理：
[0]->r:0 g:0 b:0
[1]->r:255 g:255 b:255
[2]->r:0 g:0 b:2
[3]->r:252 g:252 b:254
[4]->r:111 g:18 b:20
[5]->r:80 g:18 b:19
[6]->r:205 g:59 b:60
[7]->r:145 g:16 b:20
[8]->r:207 g:176 b:177
[9]->r:142 g:48 b:53
[10]->r:81 g:47 b:49
[11]->r:175 g:48 b:57
[12]->r:113 g:48 b:53
[13]->r:176 g:15 b:36
[14]->r:176 g:141 b:147
[15]->r:132 g:116 b:119
[16]->r:46 g:16 b:23
[17]->r:176 g:18 b:63
[18]->r:144 g:18 b:54
[19]->r:153 g:41 b:78
[20]->r:248 g:200 b:216
[21]->r:113 g:20 b:54
[22]->r:236 g:143 b:176
[23]->r:182 g:75 b:117
[24]->r:189 g:36 b:102
[25]->r:80 g:21 b:50
[26]->r:240 g:178 b:208
[27]->r:207 g:102 b:155
[28]->r:232 g:200 b:216
[29]->r:248 g:216 b:232
[30]->r:207 g:145 b:177
[31]->r:198 g:61 b:149
[32]->r:248 g:200 b:232
[33]->r:235 g:144 b:209
[34]->r:99 g:55 b:87
[35]->r:133 g:78 b:118
[36]->r:213 g:109 b:197
[37]->r:157 g:108 b:150
[38]->r:171 g:15 b:156
[39]->r:137 g:22 b:125
[40]->r:198 g:71 b:193
[41]->r:186 g:26 b:181
[42]->r:208 g:146 b:207
[43]->r:240 g:179 b:238
[44]->r:24 g:8 b:24
[45]->r:236 g:146 b:235
[46]->r:248 g:200 b:248
[47]->r:175 g:143 b:175
[48]->r:232 g:200 b:232
[49]->r:248 g:216 b:248
[50]->r:232 g:216 b:232
[51]->r:248 g:232 b:248
[52]->r:207 g:177 b:209
[53]->r:45 g:21 b:48
[54]->r:208 g:146 b:234
[55]->r:232 g:200 b:248
[56]->r:24 g:8 b:40
[57]->r:176 g:144 b:210
[58]->r:206 g:180 b:234
[59]->r:216 g:200 b:232
[60]->r:232 g:216 b:248
[61]->r:45 g:22 b:76
[62]->r:146 g:110 b:200
[63]->r:216 g:197 b:248
[64]->r:176 g:147 b:233
[65]->r:24 g:8 b:56
[66]->r:45 g:20 b:114
[67]->r:82 g:54 b:160
[68]->r:104 g:79 b:188
[69]->r:42 g:22 b:146
[70]->r:44 g:23 b:169
[71]->r:54 g:50 b:77
[72]->r:20 g:22 b:169
[73]->r:18 g:20 b:152
[74]->r:16 g:17 b:136
[75]->r:15 g:16 b:114
[76]->r:8 g:8 b:56
[77]->r:8 g:8 b:40
[78]->r:8 g:8 b:24
[79]->r:24 g:24 b:56
[80]->r:24 g:24 b:40
[81]->r:200 g:200 b:248
[82]->r:177 g:177 b:209
[83]->r:200 g:200 b:232
[84]->r:216 g:216 b:248
[85]->r:216 g:216 b:232
[86]->r:232 g:232 b:248
[87]->r:141 g:141 b:144
[88]->r:17 g:19 b:78
[89]->r:44 g:47 b:170
[90]->r:42 g:44 b:148
[91]->r:141 g:143 b:174
[92]->r:60 g:70 b:184
[93]->r:139 g:147 b:233
[94]->r:49 g:56 b:114
[95]->r:175 g:180 b:232
[96]->r:102 g:117 b:199
[97]->r:136 g:146 b:210
[98]->r:21 g:46 b:170
[99]->r:20 g:45 b:146
[100]->r:87 g:106 b:167
[101]->r:184 g:199 b:248
[102]->r:18 g:48 b:114
[103]->r:8 g:24 b:56
[104]->r:184 g:200 b:232
[105]->r:200 g:216 b:248
[106]->r:175 g:176 b:178
[107]->r:38 g:87 b:163
[108]->r:145 g:181 b:232
[109]->r:168 g:200 b:248
[110]->r:143 g:175 b:211
[111]->r:8 g:24 b:40
[112]->r:152 g:199 b:248
[113]->r:168 g:200 b:232
[114]->r:184 g:216 b:248
[115]->r:200 g:216 b:232
[116]->r:216 g:232 b:248
[117]->r:207 g:208 b:209
[118]->r:18 g:49 b:77
[119]->r:96 g:158 b:217
[120]->r:12 g:119 b:206
[121]->r:132 g:195 b:248
[122]->r:112 g:179 b:228
[123]->r:90 g:105 b:116
[124]->r:152 g:200 b:232
[125]->r:168 g:216 b:248
[126]->r:58 g:158 b:221
[127]->r:14 g:143 b:219
[128]->r:152 g:216 b:248
[129]->r:184 g:216 b:232
[130]->r:200 g:232 b:248
[131]->r:47 g:49 b:50
[132]->r:134 g:200 b:231
[133]->r:56 g:138 b:169
[134]->r:132 g:216 b:248
[135]->r:97 g:152 b:171
[136]->r:168 g:216 b:232
[137]->r:183 g:232 b:247
[138]->r:152 g:216 b:232
[139]->r:15 g:122 b:146
[140]->r:133 g:216 b:231
[141]->r:150 g:232 b:246
[142]->r:19 g:45 b:49
[143]->r:179 g:204 b:207
[144]->r:8 g:24 b:24
[145]->r:200 g:248 b:248
[146]->r:200 g:232 b:232
[147]->r:216 g:248 b:248
[148]->r:216 g:232 b:232
[149]->r:232 g:248 b:248
[150]->r:141 g:177 b:175
[151]->r:146 g:202 b:191
[152]->r:26 g:108 b:74
[153]->r:198 g:248 b:226
[154]->r:216 g:248 b:232
[155]->r:17 g:92 b:52
[156]->r:181 g:232 b:200
[157]->r:106 g:161 b:125
[158]->r:18 g:51 b:21
[159]->r:138 g:180 b:141
[160]->r:8 g:29 b:8
[161]->r:153 g:204 b:153
[162]->r:232 g:248 b:232
[163]->r:211 g:232 b:209
[164]->r:178 g:204 b:173
[165]->r:80 g:95 b:76
[166]->r:103 g:146 b:70
[167]->r:230 g:248 b:216
[168]->r:208 g:232 b:177
[169]->r:197 g:209 b:179
[170]->r:230 g:248 b:200
[171]->r:145 g:186 b:71
[172]->r:208 g:233 b:145
[173]->r:230 g:248 b:184
[174]->r:48 g:56 b:20
[175]->r:230 g:248 b:161
[176]->r:177 g:197 b:76
[177]->r:211 g:232 b:72
[178]->r:205 g:219 b:112
[179]->r:176 g:181 b:139
[180]->r:180 g:191 b:51
[181]->r:29 g:30 b:8
[182]->r:157 g:158 b:53
[183]->r:207 g:208 b:145
[184]->r:207 g:206 b:75
[185]->r:248 g:248 b:168
[186]->r:232 g:232 b:162
[187]->r:248 g:248 b:184
[188]->r:232 g:232 b:184
[189]->r:248 g:248 b:200
[190]->r:232 g:232 b:200
[191]->r:248 g:248 b:216
[192]->r:232 g:232 b:216
[193]->r:248 g:248 b:232
[194]->r:211 g:205 b:52
[195]->r:245 g:237 b:74
[196]->r:247 g:238 b:113
[197]->r:247 g:238 b:145
[198]->r:90 g:85 b:46
[199]->r:165 g:158 b:103
[200]->r:239 g:208 b:32
[201]->r:135 g:118 b:18
[202]->r:203 g:188 b:109
[203]->r:248 g:232 b:168
[204]->r:229 g:216 b:163
[205]->r:243 g:204 b:76
[206]->r:137 g:114 b:49
[207]->r:248 g:232 b:184
[208]->r:227 g:216 b:184
[209]->r:245 g:204 b:113
[210]->r:248 g:232 b:200
[211]->r:183 g:126 b:18
[212]->r:219 g:155 b:42
[213]->r:246 g:209 b:144
[214]->r:139 g:116 b:79
[215]->r:81 g:55 b:18
[216]->r:248 g:216 b:168
[217]->r:229 g:200 b:162
[218]->r:177 g:120 b:50
[219]->r:135 g:80 b:18
[220]->r:225 g:156 b:80
[221]->r:248 g:216 b:184
[222]->r:232 g:216 b:200
[223]->r:248 g:232 b:216
[224]->r:208 g:176 b:145
[225]->r:182 g:121 b:78
[226]->r:231 g:161 b:111
[227]->r:248 g:200 b:168
[228]->r:182 g:81 b:19
[229]->r:110 g:52 b:19
[230]->r:210 g:106 b:44
[231]->r:227 g:200 b:184
[232]->r:137 g:79 b:50
[233]->r:241 g:178 b:145
[234]->r:248 g:216 b:200
[235]->r:143 g:49 b:19
[236]->r:174 g:80 b:50
[237]->r:248 g:200 b:184
[238]->r:179 g:49 b:19
[239]->r:217 g:102 b:94
[240]->r:183 g:118 b:115
[241]->r:208 g:139 b:137
[242]->r:241 g:178 b:176
[243]->r:28 g:8 b:8
[244]->r:178 g:80 b:78
[245]->r:137 g:78 b:78
[246]->r:236 g:140 b:140
[247]->r:248 g:200 b:200
[248]->r:232 g:200 b:200
[249]->r:248 g:216 b:216
[250]->r:232 g:216 b:216
[251]->r:248 g:232 b:232
[252]->r:248 g:248 b:248
[253]->r:232 g:232 b:232
[254]->r:24 g:24 b:24
[255]->r:8 g:8 b:8
[You need to将colormap统一绑定到纹理单元1（绑定了颜色图纹理）。
您不需要绑定ourTexture，因为默认值为0，但是可以。
您可以使用（绑定程序时）：
glUniform1i(glGetUniformLocation(program, "colormap"), 1);
否则，两个采样器都使用纹理单元0从图像纹理读取。