Sampler1D映射空白，沒有錯誤

Question

我最終希望根據3個1d採樣器着色圖像。我寫了這個快速程序來測試我是否可以將紋理的紅色通道映射到自己，即所謂的線性映射。

儘管我在程序，着色器和一般執行過程中進行了所有錯誤檢查，但代碼仍顯示空白屏幕。當我不執行映射紋理如預期呈現。

我在使用針對Windows的GeForce Ti 550。

的方法主要是啓發自：http://www.arcsynthesis.org/gltut/Texturing/Tutorial%2014.html

使紋理和採樣

glActiveTexture(GL_TEXTURE1); 
glGenTextures(1,lut); 
glBindTexture(GL_TEXTURE_1D,lut[0]); 
unsigned char* linear = new unsigned char[256];//should be a 1->1 mapping 
for (int i = 0 ;i < 256;i++) 
{ 
    linear[i] = i; 
} 
glTexImage1D(GL_TEXTURE_1D, 0, GL_R8, 256, 0,GL_RED, GL_UNSIGNED_BYTE, linear); 
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_BASE_LEVEL, 0); 
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAX_LEVEL, 0); 
glBindTexture(GL_TEXTURE_1D, 0); 
delete linear; 
glGenSamplers(1,sampler); 
glSamplerParameteri(sampler[0], GL_TEXTURE_MAG_FILTER, GL_NEAREST); 
glSamplerParameteri(sampler[0], GL_TEXTURE_MIN_FILTER, GL_NEAREST); 
glSamplerParameteri(sampler[0], GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); 
glE();// no errors 

使程序，也沒有任何錯誤

const char *vsrc1 = 
    "attribute vec2 vecPosIn;\n" 
    "attribute vec4 texPosIn;\n" 
    "varying vec4 texPosOut;\n" 
    "void main()\n" 
    "{\n" 
    "gl_Position = vec4(vecPosIn, 0.0, 1.0);\n" 
    "texPosOut = texPosIn;\n" 
    "}\n"; 
GLint vsH = glCreateShader(GL_VERTEX_SHADER); 
glShaderSource(vsH,1,&vsrc1,NULL); 
glCompileShader(vsH); 
shaderCheck(vsH); 
glE(); 
const char *fsrc1 = 
    "uniform sampler2D tex0;\n" 
    "uniform sampler1D tex1;\n" 
    "varying vec4 texPosOut;\n" 
    "void main(void)\n" 
    "{\n" 
    //" gl_FragColor = texture2D(tex0, texPosOut.st);\n" //ignores texture and does what I expect 
    " float red = texture2D(tex0, texPosOut.st).r;\n" 
    " gl_FragColor = texture1D(tex1, red);\n" 
    "}\n"; 
GLint fsH = glCreateShader(GL_FRAGMENT_SHADER); 
glShaderSource(fsH,1,&fsrc1,NULL); 
glCompileShader(fsH); 
shaderCheck(fsH); 
glE(); 
//Bind 
programHandle = glCreateProgram(); 
glBindAttribLocation(programHandle,0,"vecPosIn"); 
glBindAttribLocation(programHandle,1,"texPosIn"); 
glBindAttribLocation(programHandle,2,"texPosOut"); 
glE(); 
//Link 
glAttachShader(programHandle, vsH); 
glAttachShader(programHandle, fsH); 
glLinkProgram(programHandle); 
programCheck(programHandle); 
glE(); 
//Set render() invariants 
glUseProgram(programHandle); 
GLuint idk = glGetUniformLocation(programHandle, "tex1"); 
glActiveTexture(GL_TEXTURE1); 
glBindTexture(GL_TEXTURE_1D,lut[0]); 
glUniform1i(idk,0); 
glBindTexture(GL_TEXTURE_1D,0); 
glUseProgram(0); 
glE(); 
//Pack static data into a VAO 
float vecData[] = { 
    -1, 1, 
    -1,-1, 
    1, 1, 
    -1,-1, 
    1,-1, 
    1, 1 
}; 
float texData[] = { 
    0,1, 
    0,0, 
    1,1, 
    0,0, 
    1,0, 
    1,1 
}; 
vboHandles=(GLuint*)malloc(sizeof(int)*2); 
glGenBuffers(2,vboHandles); 
GLuint vecBuf=vboHandles[0]; 
GLuint texBuf=vboHandles[1]; 
glBindBuffer(GL_ARRAY_BUFFER, vecBuf); 
glBufferData(GL_ARRAY_BUFFER, 8*2 * sizeof(GLfloat), vecData, GL_STATIC_DRAW); 
glBindBuffer(GL_ARRAY_BUFFER, texBuf); 
glBufferData(GL_ARRAY_BUFFER, 8*2 * sizeof(GLfloat), texData, GL_STATIC_DRAW); 
glBindBuffer(GL_ARRAY_BUFFER, 0); 
glE(); 
glGenVertexArrays(1, &vaoHandle); 
glBindVertexArray(vaoHandle); 
glEnableVertexAttribArray(0); // Vertex position 
glEnableVertexAttribArray(1); // Vertex color 
glBindBuffer(GL_ARRAY_BUFFER, vecBuf); 
glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, (GLubyte *)NULL); 
glBindBuffer(GL_ARRAY_BUFFER, texBuf); 
glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, (GLubyte *)NULL); //2 attribute per vertex 
glBindBuffer(GL_ARRAY_BUFFER,0); 
glBindVertexArray(0); 
glE(); 

渲染功能

glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT); 
glE(); 
//Bind 
glUseProgram(programHandle); 
glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D,textures[frame]); 
glActiveTexture(GL_TEXTURE1); 
glBindTexture(GL_TEXTURE_1D,lut[0]); 
GLuint idk = glGetUniformLocation(programHandle, "tex1"); 
glUniform1i(idk,0); 
glBindSampler(0,sampler[0]);glE(); 
glE(); 
//Draw 
glBindVertexArray(vaoHandle); 
glDrawArrays(GL_TRIANGLES,0,8); 
glBindVertexArray(0); 
glE(); 
//Unbind 
glActiveTexture(GL_TEXTURE1); 
glBindSampler(0,0); 
glBindTexture(GL_TEXTURE_1D,0); 
glActiveTexture(GL_TEXTURE0); 
glBindTexture(GL_TEXTURE_2D,0); 
glUseProgram(0); 
glE(); 
//DumpFrame 
glFlush(); 
glFinish(); 
glE(); 

Answer 1

要設置

glUniform1i(idk,0); 

所以你告訴GL使用紋理單元0採樣「tex1」 1D質地，因爲你必然有一個2D紋理這僅僅是無效的。