Feature/orion changes (#1359)

* Changed RenderableModel to allow user-control depth and blending.
* Updated RenderableModel to correctly handle the Orion Nebula model.
Co-authored-by: Alexander Bock <mail@alexanderbock.eu>

modules/base/shaders/model_fs.glsl

@@ -34,6 +34,7 @@ uniform float diffuseIntensity = 1.0;
 uniform float specularIntensity = 1.0;
 
 uniform bool performShading = true;
+uniform bool opacityBlending = false;
 
 uniform sampler2D texture1;
 
@@ -46,6 +47,10 @@ uniform float opacity = 1.0;
 const vec3 SpecularAlbedo = vec3(1.0);
 
 Fragment getFragment() {
+    if (opacity == 0.0) {
+        discard;
+    }
+
     vec3 diffuseAlbedo = texture(texture1, vs_st).rgb;
 
     Fragment frag;
@@ -84,12 +89,22 @@ Fragment getFragment() {
         frag.color.rgb = diffuseAlbedo;
     }
 
-    frag.color.a        = opacity;
+    if (opacityBlending) {
+        // frag.color.a = opacity * (frag.color.r + frag.color.g + frag.color.b)/3.0;
+        frag.color.a = opacity * max(max(frag.color.r, frag.color.g), frag.color.b);
+    }
+    else {
+        frag.color.a = opacity;
+    }
+
+    if (frag.color.a < 0.1) {
+        discard;
+    }
+
     frag.depth          = vs_screenSpaceDepth;
     frag.gPosition      = vs_positionCameraSpace;
     frag.gNormal        = vec4(vs_normalViewSpace, 0.0);
     frag.disableLDR2HDR = true;
 
-
     return frag;
 }