Vertex color material and shaders

The Cube component needs a Material to render it on the display. Our Cube has separate colors for each face, defined as separate vertex colors. We'll define a VertexColorMaterial instance and the corresponding shaders.

Vertex color shaders

At a minimum, the OpenGL pipeline requires that we define a vertex shader, which transforms vertices from 3D space to 2D, and a fragment shader, which calculates the pixel color values for a raster segment. Similar to the simple shaders that we created in Chapter 3, Cardboard Box, we'll create two files, vertex_color_vertex.shader and vertex_color_fragment.shader. Unless you have done so already, create a new Android resource directory with the raw type and name it raw. Then, for each file, right-click on the directory, and go to New | File. Use the following code for each of the two files. The code for the vertex shader is as follows:

// File:res/raw/vertex_color_vertex.shader
uniform mat4 u_Model;
uniform mat4 u_MVP;

attribute...