_lightAmbientLoc = gl.glGetUniformLocation(_program, "lightAmbient");
_lightDiffuseLoc = gl.glGetUniformLocation(_program, "lightDiffuse");
_textureLoc = gl.glGetUniformLocation(_program, "texture");
// Set uniform values
gl.glUniform1i(_textureLoc, 0);
// Light direction (normalized)
gl.glUniform3f(_lightDirectionLoc, 0.0f, 0.0f, -1.0f);
// Ambient light color