Vertex Attributes, Vertex Arrays, and Buffer Objects - Praise for OpenGL ES 30 Programming Guide - page 148

Example 6-5 Drawing with and without Vertex Buffer Objects (continued)

void Draw ( ESContext *esContext )
{
UserData *userData = (UserData*) esContext->userData;

// 3 vertices, with (x, y, z),(r, g, b, a) per-vertex
GLfloat vertices[3 * (VERTEX_POS_SIZE + VERTEX_COLOR_SIZE)] =
{
-0.5f, 0.5f, 0.0f, // v0
1.0f, 0.0f, 0.0f, 1.0f, // c0
-1.0f, -0.5f, 0.0f, // v1
0.0f, 1.0f, 0.0f, 1.0f, // c1
0.0f, -0.5f, 0.0f, // v2
0.0f, 0.0f, 1.0f, 1.0f, // c2
};
// index buffer data
GLushort indices[3] = { 0, 1, 2 };
glViewport ( 0, 0, esContext->width, esContext->height );
glClear ( GL_COLOR_BUFFER_BIT );
glUseProgram ( userData->programObject );
glUniform1f ( userData->offsetLoc, 0.0f );

DrawPrimitiveWithoutVBOs ( vertices,
sizeof(GLfloat) * (VERTEX_POS_SIZE + VERTEX_COLOR_SIZE),
3, indices );

// offset the vertex positions so both can be seen
glUniform1f ( userData->offsetLoc, 1.0f );

DrawPrimitiveWithVBOs ( esContext, 3, vertices,
sizeof(GLfloat) * (VERTEX_POS_SIZE + VERTEX_COLOR_SIZE),
3, indices );
}

In Example 6-5, we used one buffer object to store all the vertex data. This
demonstrates the array of structures method of storing vertex attributes
described in Example 6-1. It is also possible to have a buffer object for
each vertex attribute—that is, the structure of arrays method of storing
vertex attributes described in Example 6-2. Example 6-6 illustrates how
drawPrimitiveWithVBOs would look with a separate buffer object for
each vertex attribute.