Question

I’ve been trying to figure out how to send a texture to a shader but I can’t figure it out. My code looks fine to me but my second texture is black.

void setShaders() {

    glEnable (GL_TEXTURE_2D);
    v2 = glCreateShader(GL_VERTEX_SHADER);
    f2 = glCreateShader(GL_FRAGMENT_SHADER);    


    load_shader(v2,"a.vert");
    load_shader(f2,"a.frag");

    glCompileShader(v2);
    glCompileShader(f2);

    p = glCreateProgram();

    glAttachShader(p,v2);
    glAttachShader(p,f2);

    GLubyte* textura=LoadImageToTexture("d.jpg");
    GLubyte* textura2=LoadImageToTexture("n.jpg");

    GLuint texturaID[2];
    glGenTextures(2, texturaID);

    glBindTexture(GL_TEXTURE_2D, texturaID[0]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D,0,GL_RGBA, w, h, 0, GL_RGBA,GL_UNSIGNED_BYTE,(GLvoid*)textura );


    glBindTexture(GL_TEXTURE_2D, texturaID[1]);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
    glTexImage2D(GL_TEXTURE_2D,1,GL_RGBA, w, h, 0, GL_RGBA,GL_UNSIGNED_BYTE,(GLvoid*)textura2 );


    glLinkProgram(p);
    glUseProgram(p);
    GLint baseImageLoc = glGetUniformLocation(p, "tex");
    GLint normImage = glGetUniformLocation(p, "norm");
    glUniform1i(baseImageLoc, 0);
    glUniform1i(normImage, 1);

    glActiveTexture(GL_TEXTURE0 + 0);
    glBindTexture(GL_TEXTURE_2D, texturaID[0]);

    glActiveTexture(GL_TEXTURE0 + 1);
    glBindTexture(GL_TEXTURE_2D, texturaID[1]);

}

Shaders
[vertex]

void main()
{

    gl_TexCoord[0] = gl_MultiTexCoord0;
    gl_Position = ftransform();
}

uniform sampler2D tex;
uniform sampler2D norm;

[fragment]
void main()
{
    vec4 color = texture2D(tex,gl_TexCoord[0].st);
    vec4 color2 = texture2D(norm,gl_TexCoord[0].st);
    gl_FragColor = color*color2;
}

EDIT here is the devil!!!

   glTexImage2D(GL_TEXTURE_2D,**1**,GL_RGBA, w, h, 0, GL_RGBA,GL_UNSIGNED_BYTE,(GLvoid*)textura2 );

Instead of 1 it should be 0.

Answer 1

Your second texture seems to be created in a wrong way :

glTexImage2D(GL_TEXTURE_2D,1,...);

should be

glTexImage2D(GL_TEXTURE_2D,0,...);

As for your second question, even if I’m not sure to get it right ; when you comment the lines, you actually leave the uniform value to its default value, which is 0. The net effect is thus the same as

glUniform1i(baseImageLoc, 0);