Shade layerview elements printed with non-active extruder(s)

CURA-2025

plugins/LayerView/layers.shader

@@ -0,0 +1,35 @@
+[shaders]
+vertex =
+    uniform highp mat4 u_modelViewProjectionMatrix;
+    uniform lowp float u_active_extruder;
+    uniform lowp float u_shade_factor;
+
+    attribute highp vec4 a_vertex;
+    attribute lowp vec4 a_color;
+    varying lowp vec4 v_color;
+    void main()
+    {
+        gl_Position = u_modelViewProjectionMatrix * a_vertex;
+        // shade the color depending on the extruder index stored in the alpha component of the color
+        v_color = (a_color.a == u_active_extruder) ? a_color : a_color * u_shade_factor;
+        v_color.a = 1.0;
+    }
+
+fragment =
+    varying lowp vec4 v_color;
+
+    void main()
+    {
+        gl_FragColor = v_color;
+    }
+
+[defaults]
+u_active_extruder = 0.0
+u_shade_factor = 0.75
+
+[bindings]
+u_modelViewProjectionMatrix = model_view_projection_matrix
+
+[attributes]
+a_vertex = vertex
+a_color = color