Question

I want to load a new texture during runtime, replacing an existing loaded texture. I have looked at a similar question ( Loading new texture into already defined texture name ) but no solution seemed to be found.

I am trying to load a new 3D texture, replacing an existing 3D texture used to draw a volume in a Cg shader. However, when the new volume (or 3d texture) is loaded, the old volume is still been drawn. I create the texture by doing the following:

glGenTextures(1, &volume_texture);
glBindTexture(GL_TEXTURE_3D, volume_texture);

glTexEnvi(GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_REPLACE);
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_BORDER);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_BORDER);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_BORDER);

glTexImage3D(GL_TEXTURE_3D, 0, GL_INTENSITY, WIDTH, HEIGHT, DEPTH, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, volumeData);

When I load a new texture, I do the following (where volumeData contains the new volume texture information):

glBindTexture(GL_TEXTURE_3D, volume_texture);

glTexImage3D(GL_TEXTURE_3D, 0, GL_INTENSITY, WIDTH, HEIGHT, DEPTH, 0, GL_LUMINANCE, GL_UNSIGNED_BYTE, volumeData);

I have tried glDeleteTextures to delete the existing texture before loading the new one, but it didn’t make any difference.

The data for the texture is loaded in correctly, as after the texture is created, the same data is used to build an octree, which is built correctly as it represents the loaded volume.

For rendering, I pass the 3D texture to a Cg shader. This is done using the following call, every time the scene is drawn

SetTextureParam("volumeTex", volumeTexture, fragment_main, param3);

void SetTextureParam(char* par, GLuint tex,const CGprogram &program,CGparameter param) 
{
    param = cgGetNamedParameter(program, par); 
    cgGLSetTextureParameter(param, tex); 
    cgGLEnableTextureParameter(param);
}

Answer 1

Try using

glBindTexture(GL_TEXTURE_3D, &volume_texture);
glTexSubImage3d(GL_TEXTURE_3D, 0, 0, 0, 0, WIDTH, HEIGHT, DEPTH, GL_LUMANANCE, GL_UNSIGNED_BYTE, newVolumeData)

newVolumeData is a pointer to the new volume data.