orthographic projection matrix in Opengl-es 2.0 - opengl-es

Question

float pfIdentity[] =
{
-1.0f,0.0f,0.0f,0.0f,
0.0f,1.0f,0.0f,0.0f,
0.0f,0.0f,1.0f,0.0f,
0.0f,0.0f,0.0f,1.0f
};
==================================================================================
const char* pszVertShader = "\
attribute highp vec4 myVertex;\
uniform mediump mat4 myPMVMatrix;\
invariant gl_Position;\
void main(void)\
{\
gl_Position = myPMVMatrix * myVertex;\
}";
=====================================================================
for(int i = 0; i < 80000; ++i)
{
glClear(GL_COLOR_BUFFER_BIT);
int i32Location = glGetUniformLocation(uiProgramObject, "myPMVMatrix");
glUniformMatrix4fv( i32Location, 1, GL_FALSE, pfIdentity);
glEnableVertexAttribArray(VERTEX_ARRAY);
glVertexAttribPointer(VERTEX_ARRAY, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDrawArrays(GL_TRIANGLES, 0,i);
eglSwapBuffers(eglDisplay, eglSurface);
}
return 0;
}
p.s : i am doing opengl-es in ubuntu 10.10 with kronos headers , its an emulator for opengl-es 2.0 in linux.

Answer 1

You don't have a projection at all. The Projection-Model-View matrix you're setting the myPMVMatrix uniform to is
float pfIdentity[] =
{
-1.0f,0.0f,0.0f,0.0f,
0.0f,1.0f,0.0f,0.0f,
0.0f,0.0f,1.0f,0.0f,
0.0f,0.0f,0.0f,1.0f
};
/* ... */
glUniformMatrix4fv( i32Location, 1, GL_FALSE, pfIdentity);
BTW: The idea of uniforms is, that you don't set them at each primitive iteration.
Anyway, this is a identity matrix, and since it's the only transformation applied it will just pass through the vertices as they are to the fragment stage. The solution for your problem is applying a orthographic projection to it, i.e. multiply that matrix with a ortho projection matrix and use the result of that operation instead. http://www.songho.ca/opengl/gl_projectionmatrix.html