T2.1 Draw two triangles using vertex indices

Github code

Release tag_a_two_triangle · zhaoyoubing/proj02GitHub

Now we are drawing two triangles.

One way is to use the method in Lab 01 to draw two triangles. However, it is not very efficient as you have to duplicate vertices.

    GLfloat verts[] = {
        -1.0f, 1.0f,  // v0
        -1.0f, -1.0f, // v1
        1.0f, -1.0f,  // v2

        1.0f, -1.0f,  // v2
        1.0f, 1.0f,   // v3
        -1.0f, 1.0f,  // v0
    };

This week we are going to learn use vertex with indices to draw multiple triangles.