OpenGL Terrain Texture3D Map

Question

In OpenGL I am trying to map a terrain with 8 512x512 images using texture3D to get blended texture change. But OpenGL forces me to allocate 512x512x512 array instead of 512x512x8 What can be solution

Answer 1

But Opengl forces me to allocate 512x512x512

What gave you that idea? 512×512×8 is a completely valid 3D texture size. For terrains you might also look at GL_TEXTURE_2D_ARRAY, which is initialized with glTexImage3D as well, but doesn't interpolate between the layers, which is usefull in certain situations.

Answer 2

Even though you need interpolation to blend one texture into another, you should also try using a GL_TEXTURE_2D_ARRAY and just manually blend the textures together in the fragment shader. Although it might seem that it's better to take advantage of the automatic hardware magnification filter, bear in mind that for GL_TEXTURE_3D implementation it's far more likely that the neighboring pixels in 6 directions will get cached, and from what I understand you have more emphasis on the individual 2D textures in the set and their neighboring layers, so you're better off having the hardware make 3 cache lines, each in 4 directions. It's a good idea to try both and see what performs better