I have problems to use 1D textures in OpenGL 4.x.
I create my 1d texture this way (BTW: I removed my error checks to make the code more clear and shorter - usually after each gl call a BLUE_ASSERTEx(glGetError() == GL_NO_ERROR, "glGetError failed.");
follows):
glGenTextures(1, &textureId_);
// bind texture
glBindTexture(GL_TEXTURE_1D, textureId_);
// tells OpenGL how the data that is going to be uploaded is aligned
glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
BLUE_ASSERTEx(description.data, "Invalid data provided");
glTexImage1D(
GL_TEXTURE_1D, // Specifies the target texture. Must be GL_TEXTURE_1D or GL_PROXY_TEXTURE_1D.
0, // Specifies the level-of-detail number. Level 0 is the base image level. Level n is the nth mipmap reduction image.
GL_RGBA32F,
description.width,
0, // border: This value must be 0.
GL_RGBA,
GL_FLOAT,
description.data);
BLUE_ASSERTEx(glGetError() == GL_NO_ERROR, "glGetError failed.");
// texture sampling/filtering operation.
glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_WRAP_T, GL_REPEAT);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri (GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glBindTexture(GL_TEXTURE_1D, 0);
After the creation I try to read the pixel data of the created texture this way: const int width = width_; const int height = 1;
// Allocate memory for depth buffer screenshot
float* pixels = new float[width*height*sizeof(buw::vector4f)];
// bind texture
glBindTexture(GL_TEXTURE_1D, textureId_);
glPixelStorei(GL_PACK_ALIGNMENT, 1);
glReadPixels(0, 0, width, height, GL_RGBA, GL_FLOAT, pixels);
glBindTexture(GL_TEXTURE_1D, 0);
buw::Image_4f::Ptr img(new buw::Image_4f(width, height, pixels));
buw::storeImageAsFile(filename.toCString(), img.get());
delete pixels;
But the returned pixel data is different to the input pixel data (input: color ramp, ouptut: black image)
Any ideas how to solve the issue? Maybe I am using a wrong API call.
Replacing glReadPixels
by glGetTexImage
does fix the issue.