how to render multiple textures with GLSL

Question

i am about to port all my rendering from "old" opengl to glsl.

now i have a mesh with different textures, so in "old" gl i just used bindTexture to change the texture. i guess, i still need to do this, but something is missing, since my everything seems to be rendered with the first texture only.

uniform sampler2D tex;
void main() {
    gl_FragColor = tex2D(tex, gl_TexCoord[0].st);
}

"tex" is the name of the texture which i put to glsl like this:

int loc = glGetUniformLocationARB(id, "tex");
glUniform1iARB(loc, 0);

note: i am not talking about multitexturing! :-)

Answer 1

You have bound texture unit 0 to the sampler2D, but you need to bind the texture to the texture unit as well. So that'd be simply a glBindTexture call.

Answer 2

i was confused with the way to tell GLSL which texture unit to use for which sampler as well. i searched hours for my problem and could not solve it because i think this topic is not very well explained in all the literature out there.

here is a valuable explaination: (see the part "Using Textures With GLSL") http://nehe.gamedev.net/data/articles/article.asp?article=21

maybe this helps somebody!