Texturing - Praise for OpenGL ES 30 Programming Guide - page 259

Example 9-4 Loading a Cubemap Texture (continued)

// Load the cube face - Positive Z
glTexImage2D(GL_TEXTURE_CUBE_MAP_POSITIVE_Z, 0, GL_RGB, 1, 1,
0, GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[4]);

// Load the cube face - Negative Z
glTexImage2D(GL_TEXTURE_CUBE_MAP_NEGATIVE_Z, 0, GL_RGB, 1, 1,
0, GL_RGB, GL_UNSIGNED_BYTE, &cubePixels[5]);

// Set the filtering mode
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MIN_FILTER,
GL_NEAREST);
glTexParameteri(GL_TEXTURE_CUBE_MAP, GL_TEXTURE_MAG_FILTER,
GL_NEAREST);
return textureId;
}

This code loads each individual cubemap face with l × l RGB pixel data by
calling glTexImage2D for each cubemap face. The shader code to render
the sphere with a cubemap is provided in Example 9-5.

Example 9-5 Vertex and Fragment Shader Pair for Cubemap Texturing

// Vertex shader
#version 300 es
layout(location = 0) in vec4 a_position;
layout(location = 1) in vec3 a_normal;
out vec3 v_normal;
void main()
{
gl_Position = a_position;
v_normal = a_normal;
}

// Fragment shader
#version 300 es
precision mediump float;
in vec3 v_normal;
layout(location = 0) out vec4 outColor;
uniform samplerCube s_texture;
void main()
{
outColor = texture( s_texture, v_normal );
}