Removed submodule maplibre-gl-js (#938)

shaders/debug.vertex.glsl

@@ -0,0 +1,12 @@
+attribute vec2 a_pos;
+varying vec2 v_uv;
+
+uniform mat4 u_matrix;
+uniform float u_overlay_scale;
+
+void main() {
+    // This vertex shader expects a EXTENT x EXTENT quad,
+    // The UV co-ordinates for the overlay texture can be calculated using that knowledge
+    v_uv = a_pos / 8192.0;
+    gl_Position = u_matrix * vec4(a_pos * u_overlay_scale, 0, 1);
+}