opengl.shaders: Use unified lighting and texturing 'snippets' for fragment shaders.

3-mid/opengl/assets/shader/texturing-frag.snippet

@@ -0,0 +1,27 @@
+uniform int         texture_Count;
+uniform sampler2D   Textures [32];
+uniform float       Fade     [32];
+
+vec4
+apply_Texturing (vec2   Coords)
+{
+    vec4   Color = vec4 (0);
+
+    for (int i = 0;   i < texture_Count;   ++i)
+    {
+        Color.rgb +=   texture (Textures [i], Coords).rgb
+                     * texture (Textures [i], Coords).a
+                     * (1.0 - Fade [i]);
+                                      
+//        Color.a    += texture (Textures [i],  Coords).a * (1.0 - Fade[1]);
+
+        Color.a    = max (Color.a,
+                          texture (Textures [i],Coords).a * (1.0 - Fade[i]));
+
+
+//        Color.a    = max (Color.a,
+//                            texture (Textures [i],Coords).a);
+    }
+    
+    return Color;
+}