Application crash on glColor4f OpenGl function in IOS

Question

I am working on OpenCV client app, my application works fine on IOS 5.1 but when i run my application on IOS 4.3 then it crashed at glColor4f function which defined in gl.h class, but it not show any error message on crash. I am doing like following:

QCAR::Matrix44F modelViewProjection;


                glColor4f(0.5f,0.0f,0.0f,0.0f);
                ShaderUtils::multiplyMatrix(&qUtils.projectionMatrix.data[0], &modelViewMatrix.data[0], &modelViewProjection.data[0]);
                glUseProgram(shaderProgramID);
                glVertexAttribPointer(vertexHandle, 3, GL_FLOAT, GL_FALSE, 0, (const GLvoid*) &vbVertices[0]);
                glEnableVertexAttribArray(vertexHandle);
                glUniformMatrix4fv(mvpMatrixHandle, 1, GL_FALSE, (GLfloat*)&modelViewProjection.data[0] );
                glColor4f(0.5f,0.0f,0.0f,0.0f);

                glEnableClientState (GL_VERTEX_ARRAY);
                glEnableClientState (GL_COLOR_ARRAY); 
                glEnableClientState(GL_COLOR_ARRAY);    
              //  glColorPointer(4, GL_FLOAT, 0, triangleColors);  
                glVertexPointer(3, GL_FLOAT, 0, (const GLvoid*) &vbVertices[0]); 
                glDisableClientState(GL_TEXTURE_COORD_ARRAY);
                glDisable(GL_TEXTURE_2D);
                glDrawArrays(GL_LINES, 0, 8);
                //glDisableClientState(GL_TEXTURE_COORD_ARRAY);
                //glDisable(GL_TEXTURE_2D);
                glDisableVertexAttribArray(vertexHandle);

Answer 1

I've done some research and here's a couple of things for you to try:

• Experiment the glColor4d()instead, which takes 4 double parameters;
• You might be calling a null function pointer, hence the crash. That happens when the load procedure doesn't call getProc for glColor4f;
• Try calling glGetError() before glColor4f() to know if there are problem on the GL side of things.

Also, someone replied your question in this thread. He might be right.

Answer 2

glColor4f() is only used with the OpenGL ES 1.1 fixed function pipeline. From the use of glUseProgram() in your above code, you're working in OpenGL ES 2.0, therefore glColor4f() is not supported.

If you wish to set the color of your materials, you will need to do that via a uniform in your shader program. If you instead want to just set the background color of your scene, you'd use something like the following:

    glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
    glClear(GL_COLOR_BUFFER_BIT);