Update code to use image textures

shaders/vert.glsl

@@ -2,10 +2,13 @@
 
 layout(location=0) in vec3 position;
 layout(location=1) in vec3 color;
+layout(location=2) in vec2 uv;
 
 out vec3 vert_color;
+out vec2 tex_coords;
 
 void main() {
-  vert_color = color;
+  tex_coords  = uv;
+  vert_color  = color;
   gl_Position = vec4(position, 1.0);
 };