HOWTO create OpenGL ES 2.0 SkyBox? - dictionary

Question

Can you give me hint to any good SkyBox example in OpenGL ES 2.0? I have found only OpenGL and does not work for me.
I am doing it this way:
Initialization:
glUseProgram(m_programSkyBox.Program);
glGenBuffers(1, &skyBoxVertexBuffer);
glBindBuffer(GL_ARRAY_BUFFER, skyBoxVertexBuffer);
float vertices[24] = {
-1.0, -1.0, 1.0,
1.0, -1.0, 1.0,
-1.0, 1.0, 1.0,
1.0, 1.0, 1.0,
-1.0, -1.0, -1.0,
1.0, -1.0, -1.0,
-1.0, 1.0, -1.0,
1.0, 1.0, -1.0,
};
glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices, GL_STATIC_DRAW);
glGenBuffers(1, &skyBoxIndexBuffer);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, skyBoxIndexBuffer);
GLubyte indices[14] = {0, 1, 2, 3, 7, 1, 5, 4, 7, 6, 2, 4, 0, 1};
glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices, GL_STATIC_DRAW);
Drawing the skybox:
glClearColor(0.5f, 0.5f, 0.5f, 1);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
glUseProgram(m_programSkyBox.Program);
glDisable(GL_DEPTH_TEST); // skybox should be drawn behind anything else
glBindTexture(GL_TEXTURE_CUBE_MAP, m_textures.Cubemap);
glBindBuffer(GL_ARRAY_BUFFER, skyBoxVertexBuffer);
glVertexAttribPointer(m_programSkyBox.Attributes.Position, 3, GL_FLOAT, GL_FALSE, 0, (void*)0);
glEnableVertexAttribArray(m_programSkyBox.Attributes.Position);
glBindBuffer(GL_ARRAY_BUFFER, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, skyBoxIndexBuffer);
glDrawElements(GL_TRIANGLE_STRIP, 14, GL_UNSIGNED_BYTE, 0);
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
glEnable(GL_DEPTH_TEST);
Texture loading is working. Shader is correctly compiled and looks like this:
Vertex shader:
attribute vec4 position;
varying mediump vec3 texCoord;
void main() {
texCoord.xyz = position.xyz;
}
Fragment shader:
uniform samplerCube Sampler;
varying mediump vec3 texCoord;
void main() {
mediump vec3 cube = vec3(textureCube(Sampler, texCoord.xyz));
gl_FragColor = vec4(cube, 1.0);
}
But I cant get cube visible. Am I doing anything wrong?
Thank you

Answer 1

My fault, I have found the problem. I have not "create" vertex in vertex shader. It should looks this way:
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
attribute vec4 position;
varying mediump vec4 texCoord;
void main() {
texCoord = position;
gl_Position = projectionMatrix * modelViewMatrix * position;
}