int Init ( ESContext *esContext )
{
esContext->userData = malloc(sizeof(UserData));
UserData *userData = esContext->userData;
GLbyte vShaderStr[] =
"uniform mat4 u_mvpMatrix; \n"
"attribute vec4 a_position; \n"
"void main() \n"
"{ \n"
" gl_Position = u_mvpMatrix * a_position; \n"
"} \n";
GLbyte fShaderStr[] =
"precision mediump float; \n"
"void main() \n"
"{ \n"
" gl_FragColor = vec4( 1.0, 0.0, 0.0, 1.0 ); \n"
"} \n";
// Load the shaders and get a linked program object
userData->programObject = esLoadProgram ( vShaderStr, fShaderStr );
// Get the attribute locations
userData->positionLoc = glGetAttribLocation ( userData->programObject, "a_position" );
// Get the uniform locations
userData->mvpLoc = glGetUniformLocation( userData->programObject, "u_mvpMatrix" );
// Generate the vertex data
userData->numIndices = esGenCube( 1.0, &userData->vertices,
NULL, NULL, &userData->indices );
// Starting rotation angle for the cube
userData->angle = 45.0f;
glClearColor ( 0.0f, 0.0f, 0.0f, 0.0f );
return GL_TRUE;
}
void Draw ( ESContext *esContext )
{
UserData *userData = esContext->userData;
// Set the viewport
glViewport ( 0, 0, esContext->width, esContext->height );
// Clear the color buffer
glClear ( GL_COLOR_BUFFER_BIT );
// Use the program object
glUseProgram ( userData->programObject );
// Load the vertex position
glVertexAttribPointer ( userData->positionLoc, 3, GL_FLOAT,
GL_FALSE, 3 * sizeof(GLfloat), userData->vertices );
glEnableVertexAttribArray ( userData->positionLoc );
// Load the MVP matrix
glUniformMatrix4fv( userData->mvpLoc, 1, GL_FALSE, (GLfloat*) &userData->mvpMatrix.m[0][0] );
// Draw the cube
glDrawElements ( GL_TRIANGLES, userData->numIndices, GL_UNSIGNED_SHORT, userData->indices );
}
------------
注意: glGetAttribLocation 及 glVertexAttribPointer；
注意: glGetUniformLocation 及 glUniformMatrix4fv；