/** * Returns the vertex shader program. Note that this program <em>must</em> preserve the use of * the existing attributes and uniforms. You can add new uniforms and attributes, but you cannot * remove or change the defaults. */ protected String vertexShader() { return baseVertexShader().replace("_MAX_QUADS_", ""+maxQuads). replace("_VEC4S_PER_QUAD_", ""+vec4sPerQuad()); }