As I know, OpenGL has highly supported NPOT textures since 3.0. Now I’ m facing an bizarre phenomenon that NPOT texture cannot be allocated with precise corresponding data.
Words are plain. My testing code is as below.
glGenTextures(1, &texVoxels); glBindTexture(GL_TEXTURE_3D, texVoxels); glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE); int width = 513; int height = 513; int depth = 513; unsigned char *data = new unsigned char[width*height*depth]; memset(data, 0, sizeof(unsigned char)*width*height*depth); glTexImage3D(GL_TEXTURE_3D, 0, GL_LUMINANCE8, width, height,depth, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, data); delete data; data = NULL;
As code shown above, I need to allocate an NPOT cubic texture of 2^N +1. But program will exit error on glTexImage3D(). The error, I think, is caused by “the size of data less than the texture needed”. Because if I allocate data larger enough, the program will pass.
Could anybody please explain this thing for me? I think it is a hardware-related question. Anyway, how could I use NPOT texture and allocate data like this? Even though when the size of data is larger enough the program passes, I am really not sure about how data exactly corresponds to the texture location then.
PS. My graphic card is quadro fx 4800, which supports OpenGL 3.3.