Sampler1D映射空白，没有错误

Question

我最终希望基于3个1d采样器对图像进行着色。我写了这个快速程序来测试我是否可以将纹理的红色通道映射到它自己，这就是所谓的线性映射。

尽管我在程序、着色器和一般执行中进行了所有错误检查，但现在代码显示的是一个空白屏幕。当我不执行贴图时，纹理会按预期进行渲染。

我使用的是GeForce Ti 550，目标是Windows。

该方法的主要灵感来源于：http://www.arcsynthesis.org/gltut/Texturing/Tutorial%2014.html

制作纹理和采样器

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

制作程序，也没有错误

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

您正在设置

glUniform1i(idk,0);

所以你告诉GL使用纹理单元0来采样"tex1"1D纹理，这是无效的，因为你有一个2D纹理绑定在那里。