Initial material graph nodes for textures mapped to world uvs

exts/cesium.omniverse/mdl/cesium.mdl

@@ -0,0 +1,57 @@
+mdl 1.7;
+
+import ::anno::*;
+import ::state::*;
+import ::tex::*;
+
+module [[
+	anno::version( 1, 0, 0),
+	anno::display_name("Cesium MDL functions")
+]];
+
+export float2 world_coordinate_2d(float2 min_world_xy=float2(-5000.0,-5000.0), float2 max_world_xy=float2(5000.0,5000.0))
+[[
+    anno::display_name("World Coordinate 2D"),
+    anno::description("Returns UV coordinates for mapping rasters to world space positions."),
+    anno::author("Cesium"),
+	anno::in_group("Cesium functions"),
+	anno::ui_order(300)
+]]{
+	// Get the world pos of the pixel
+	float3 world_pos = state::transform_vector(state::coordinate_internal, state::coordinate_world, state::position());
+
+	// Return 0-1 UVs based on the min/max world coordinates provided 
+	return float2(0.0,0.0) + (float2(world_pos.x, world_pos.y) - min_world_xy) * (float2(1.0, 1.0) - float2(0.0, 0.0)) / (max_world_xy - min_world_xy);
+}
+
+export float4 lookup_world_texture_float4(uniform texture_2d texture = texture_2d(), float2 min_world_xy=float2(-5000.0,-5000.0), float2 max_world_xy=float2(5000.0,5000.0))
+[[
+    anno::display_name("World-mapped texture lookup float4"),
+    anno::description("Returns float4 from a texture mapped to world UV coordinates"),
+    anno::author("Cesium GS Inc."),
+	anno::in_group("Cesium functions"),
+	anno::ui_order(300)
+]]
+{
+	return tex::lookup_float4(
+        tex: texture,
+        coord: world_coordinate_2d(min_world_xy, max_world_xy),
+        wrap_u: ::tex::wrap_clamp,
+        wrap_v: ::tex::wrap_clamp);
+}
+
+export color lookup_world_texture_color(uniform texture_2d texture = texture_2d(), float2 min_world_xy=float2(-5000.0,-5000.0), float2 max_world_xy=float2(5000.0,5000.0))
+[[
+    anno::display_name("World-mapped texture lookup color"),
+    anno::description("Returns color from a texture mapped to world UV coordinates"),
+    anno::author("Cesium GS Inc."),
+	anno::in_group("Cesium functions"),
+	anno::ui_order(300)
+]]
+{
+	return tex::lookup_color(
+        tex: texture,
+        coord: world_coordinate_2d(min_world_xy, max_world_xy),
+        wrap_u: ::tex::wrap_clamp,
+        wrap_v: ::tex::wrap_clamp);
+}