Question

I am trying to use multiple textures in the same scene but no matter what I try the same texture is loaded for each object. So this what I am doing at the moment, I initialise each shader:

rightWall.SendShaders("wall.vert","wall.frag","brick3.bmp", "wallTex", 0);      
demoFloor.SendShaders("floor.vert","floor.frag","dirt1.bmp", "floorTex", 1);

The code in SendShaders is:

            GLuint vert,frag;
            glEnable(GL_DEPTH_TEST);
            glEnable(GL_TEXTURE_2D);

            char *vs = NULL,*fs = NULL;

            vert = glCreateShader(GL_VERTEX_SHADER);
            frag = glCreateShader(GL_FRAGMENT_SHADER);

            vs = textFileRead(vertFile);
            fs = textFileRead(fragFile);
            const char * ff = fs;
            const char * vv = vs;

            glShaderSource(vert, 1, &vv, NULL);
            glShaderSource(frag, 1, &ff, NULL);

            free(vs); free(fs);

            glCompileShader(vert);
            glCompileShader(frag);

            program = glCreateProgram();
            glAttachShader(program, frag);
            glAttachShader(program, vert);

            glLinkProgram(program);
            glUseProgram(program);

        LoadGLTexture(textureImage, texture);

And then in the main loop:

rightWall.UseShader("wallTex");
rightWall.Draw();   

demoFloor.UseShader("floorTex");
demoFloor.Draw();

The code in UseShader:

void GraphicsObject::UseShader(char textureName []){

glUseProgram(program);  
GLint location = glGetUniformLocation(program, textureName);
glUniform1i(location, 0); 
glActiveTexture(GL_TEXTURE0);           
glBindTexture(GL_TEXTURE_2D, texture);

}

And finally, the texture load methods:

int GraphicsObject::LoadGLTexture(const char fileName []){

AUX_RGBImageRec *TextureImage[1]; // Create Storage Space For The Texture
memset(TextureImage,0,sizeof(void *)*1); // Set The Pointer To NULL
int arraySize = strlen(fileName); 
arraySize += 1;
 if (TextureImage[0]=LoadBMP(fileName, arraySize))
{
              glGenTextures(1, &texture);
    glBindTexture(GL_TEXTURE_2D, texture);
    glTexParameteri(GL_TEXTURE_2D, GL_GENERATE_MIPMAP, GL_TRUE);
    glTexImage2D(GL_TEXTURE_2D, 0, GL_RGB, TextureImage[0]->sizeX, 
    TextureImage[0]->sizeY, 0, GL_RGB,         
     GL_UNSIGNED_BYTE, TextureImage[0]->data);

    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);       
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);       
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_NEAREST);        
    glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_NEAREST);        
 }
if (TextureImage[0])
{
        if (TextureImage[0]->data)
    {
            free(TextureImage[0]->data);    
                }
    free(TextureImage[0]);              
}   

return 1;

}

AUX_RGBImageRec* GraphicsObject::LoadBMP(const char fileName[], int arraySize){

FILE *File=NULL; 
LPWSTR pwszFileName;
int lenW;
BSTR unicodestr;

lenW = MultiByteToWideChar(CP_ACP, 0, fileName, arraySize, 0,0);

DWORD bottom = GetLastError();
unicodestr = SysAllocStringLen(0, lenW);

MultiByteToWideChar(CP_ACP,0, fileName, arraySize,
    unicodestr,lenW);
SysFreeString(unicodestr);
DWORD tit = GetLastError();

if (!fileName) 
{
    return NULL; 
}

File=fopen(fileName,"r"); 

if (File) 
{
    fclose(File);
    return auxDIBImageLoad((LPCWSTR)unicodestr);
}
return NULL;

}

Which ever shader is initialised last is the texture which is used for both objects. Thank you for your time and I appreciate any comments.

Answer 1

Like you have to call glUseProgram(program) before using the shader for rendering, you also have to bind the right texture directly before rendering.

The code should look like this:

glUseProgram(program1);
glBindTexture(GL_TEXTURE_2D, texture1);
// render calls for object 1

glUseProgram(program2);
glBindTexture(GL_TEXTURE_2D, texture2);
// render calls for object 2

Moreover also Uniforms must be set directly before rendering, and not at shader intialization.

So in your case the part

GLint location = glGetUniformLocation(program, textureName);
glUniform1i(location, 0);
glActiveTexture(GL_TEXTURE0);           
glBindTexture(GL_TEXTURE_2D, texture);

does not belong in the function SendShaders, but in UseShader!