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Asem

Multi-Texturing Problem

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I tried to use multi-texturing but for some reason I can't get it to work. I made sure that I support the extension and how many texture units I support( which is 4). I've followed many tutorials but I can't get it to work like I missing something but I have no clue what. The only texture that shows up is the one that was called last (using glBindTexture) regardless of active texture unit. I use the devIL image library to load my images and it works great so I know that library is not the problem. This is what I have trying to combine 2 textures...
[source lang="cpp"}


#include "OGL.h"

OGL::OGL()
{
}


OGL::~OGL()
{
    glDeleteTextures(1, &tId);
    ilDeleteImages(1, &iId);

    glDeleteTextures(1, &tId2);
    ilDeleteImages(1, &iId2);
}

void OGL::init()
{

{//DevIL Used


    ///Load Textures
    glEnable(GL_TEXTURE_2D);
    glEnable( GL_ALPHA_TEST );
    glAlphaFunc(GL_GREATER, 0.0);

    ilInit();

    ilGenImages(1, &iId);
    ilGenImages(1, &iId2);

    ilBindImage(iId);
    ilLoadImage("./test.png");

    iData = ilGetData();
    w = ilGetInteger(IL_IMAGE_WIDTH);
    h = ilGetInteger(IL_IMAGE_HEIGHT);

    glEnable( GL_TEXTURE_2D );

    glEnable(GL_TEXTURE_2D);
    glGenTextures(1, &tId);
    glBindTexture(GL_TEXTURE_2D, tId);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, iData);

    ///
    ilBindImage(iId2);

    ilLoadImage("./test2.png");

    iData = ilGetData();
    w = ilGetInteger(IL_IMAGE_WIDTH);
    h = ilGetInteger(IL_IMAGE_HEIGHT);

    glGenTextures(1, &tId2);
    glBindTexture(GL_TEXTURE_2D, tId2);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);

    glTexImage2D( GL_TEXTURE_2D, 0, GL_RGBA, w, h, 0, GL_RGBA, GL_UNSIGNED_BYTE, iData);

}




///Set texture units

    
    glActiveTextureARB(GL_TEXTURE0_ARB );
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, tId);
    glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
    glTexEnvf (GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_REPLACE);


    glActiveTextureARB(GL_TEXTURE1_ARB );
    glEnable(GL_TEXTURE_2D);
    glBindTexture(GL_TEXTURE_2D, tId2);
    glTexEnvf (GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_COMBINE_EXT);
    glTexEnvf (GL_TEXTURE_ENV, GL_COMBINE_RGB_EXT, GL_INCR);



    glActiveTextureARB(GL_TEXTURE0_ARB);

}


void OGL::draw(float t)
{
    //Clear Background
    glClear(GL_COLOR_BUFFER_BIT);

    glMatrixMode( GL_MODELVIEW );
    glLoadIdentity();

    glBindTexture(GL_TEXTURE_2D, tId);

    glPushMatrix();
    glBegin(GL_TRIANGLES);

         glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.0f,   1.0f);
         glMultiTexCoord2fARB(GL_TEXTURE1_ARB, 0.0f,   1.0f);
           glVertex2f(0.0f,   1.0f);

         glMultiTexCoord2fARB(GL_TEXTURE0_ARB, 0.87f,  -0.5f);
         glMultiTexCoord2fARB(GL_TEXTURE1_ARB, 0.87f,  -0.5f);
           glVertex2f(0.87f,  -0.5f);

         glMultiTexCoord2fARB(GL_TEXTURE0_ARB, -0.87f,  -0.5f);
         glMultiTexCoord2fARB(GL_TEXTURE1_ARB, -0.87f,  -0.5f);
           glVertex2f(-0.87f, -0.5f);

    glEnd();

    glPopMatrix();

    glFlush();

}





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I think you will want to enable blend mode and setting some reasonable blend function - I don't see anything obviously wrong so I suspect you're actually getting both textures, but they are not being combined.

By the way, why do you have negative texture coordinates? Usually they are clamped between 0 and 1.

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oops, sorry I didn't notice that I had another post because gamedev was running so slow that I didn't think the post went through. Thanks for the suggestions though.

About the texcoords I figured you could think of them as being on an xy grid which in this case is not a problem since it still worked but I get what your saying. I also did it just to do a quick test to see if I could get the multi texturing to work because the multi-tex shader I made was not doing what I expected.

It Worked! Now to try the same thing with my shader.

[Edited by - Asem on June 9, 2009 4:31:45 AM]

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