Apply mask to height

Sources/arm/node/MakeMesh.hx

@@ -39,6 +39,10 @@ class MakeMesh {
 				numLayers++;
 				vert.add_uniform('sampler2D texpaint_pack_vert' + l.id, '_texpaint_pack_vert' + l.id);
 				vert.write('height += textureLod(texpaint_pack_vert' + l.id + ', tex, 0.0).a;');
+				if (l.texpaint_mask != null) {
+					vert.add_uniform('sampler2D texpaint_mask_vert' + l.id, '_texpaint_mask_vert' + l.id);
+					vert.write('height *= textureLod(texpaint_mask_vert' + l.id + ', tex, 0.0).r;');
+				}
 			}
 			vert.write('wposition += wnormal * vec3(height, height, height) * vec3($displaceStrength, $displaceStrength, $displaceStrength);');
 		}

Sources/arm/render/Uniforms.hx

@@ -338,6 +338,10 @@ class Uniforms {
 			var tid = link.substr(link.length - 1);
 			return RenderPath.active.renderTargets.get("texpaint_pack" + tid).image;
 		}
+		if (link.startsWith("_texpaint_mask_vert")) {
+			var tid = Std.parseInt(link.substr(link.length - 1));
+			return Project.layers[tid].texpaint_mask;
+		}
 
 		if (link == "_texpaint_mask") {
 			return Context.layer.texpaint_mask;