Here is a very little explanation on how to draw a textured or untextured object, assuming you already know about GU. Here is the skeleton of a very simple textured object and one untextured object.
VERTEX_TYPE *vertices;
vertices = (VERTEX_TYPE*)sceGuGetMemory(NUMBER_OF_VERTICES * sizeof(vertices[0]));
vertices[0].something = ...;
[...]
sceGuDrawArray(PRIMITIVETYPE, VERTEX_DESCRIPTION | GU_TRANSFORM_2D, NUMBER_OF_VERTICES, 0, vertices);
}
void drawSomethingUntextured(
OSL_IMAGE *img) {
VERTEX_TYPE *vertices;
vertices = (VERTEX_TYPE*)sceGuGetMemory(NUMBER_OF_VERTICES * sizeof(vertices[0]));
vertices[0].something = ...;
[...]
sceGuDrawArray(PRIMITIVETYPE, VERTEX_DESCRIPTION | GU_TRANSFORM_2D, NUMBER_OF_VERTICES, 0, vertices);
}
As you see, it's very simple, if you're used to GU. If not, please read tutorials and examples from ps2dev.org.