Use a fragment shader as well as a vertex shader for the skinned meshes.

I tracked the ATI slowdown down to using a vertex shader in combination 
with fixed function fog.  Also cleaned up ShaderConfig a little.


git-svn-id: svn+ssh://src.earth.threerings.net/nenya/trunk@244 ed5b42cb-e716-0410-a449-f6a68f950b19

rsrc/media/jme/skin.frag

@@ -0,0 +1,56 @@
+//
+// $Id: ImageCache.java 158 2007-02-24 00:38:17Z mdb $
+//
+// Nenya library - tools for developing networked games
+// Copyright (C) 2002-2007 Three Rings Design, Inc., All Rights Reserved
+// http://www.threerings.net/code/nenya/
+//
+// This library is free software; you can redistribute it and/or modify it
+// under the terms of the GNU Lesser General Public License as published
+// by the Free Software Foundation; either version 2.1 of the License, or
+// (at your option) any later version.
+//
+// This library is distributed in the hope that it will be useful,
+// but WITHOUT ANY WARRANTY; without even the implied warranty of
+// MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+// Lesser General Public License for more details.
+//
+// You should have received a copy of the GNU Lesser General Public
+// License along with this library; if not, write to the Free Software
+// Foundation, Inc., 59 Temple Place, Suite 330, Boston, MA 02111-1307 USA
+
+/** The diffuse texture map. */
+uniform sampler2D diffuseMap;
+
+/** The emissive texture map. */
+#ifdef EMISSIVE_MAPPED
+    uniform sampler2D emissiveMap;
+#endif
+
+/** The amount of fog. */
+#ifdef FOG
+    varying float fogAlpha;
+#endif
+
+/**
+ * Fragment shader for skinned meshes.
+ */
+void main ()
+{
+    // start with the diffuse color
+    vec4 fragColor = texture2D(diffuseMap, gl_TexCoord[0].st);
+
+    // modulate by the light color
+    #ifdef EMISSIVE_MAPPED
+        fragColor *= (gl_Color + vec4(texture2D(emissiveMap, gl_TexCoord[0].st).rgb, 0.0));
+    #else
+        fragColor *= gl_Color;
+    #endif
+
+    // blend between the computed color and the fog color
+    #ifdef FOG
+        gl_FragColor = mix(gl_Fog.color, fragColor, fogAlpha);
+    #else
+        gl_FragColor = fragColor;
+    #endif
+}

rsrc/media/jme/skin.vert

@@ -38,6 +38,11 @@ attribute ATTRIB_TYPE boneIndices;
 /** The bone weights. */
 attribute ATTRIB_TYPE boneWeights;
 
+/** The amount of fog. */
+#ifdef FOG
+  varying float fogAlpha;
+#endif
+
 /**
  * Vertex shader for skinned meshes.
  */
@@ -65,12 +70,12 @@ void main ()
     vec3 eyeVertex = vec3(gl_ModelViewMatrix * modelVertex);
     vec3 eyeNormal = normalize(vec3(gl_ModelViewMatrixInverseTranspose * modelNormal));
 
-    // eye space 'z' is the standard fog coordinate
-    gl_FogFragCoord = -eyeVertex.z;
-
     // set gl_FrontColor based on vertex, normal and light parameters
     SET_FRONT_COLOR
 
     // set the varying texture coordinates
     SET_TEX_COORDS
+
+    // set the fog alpha based on the eye space vertex
+    SET_FOG_ALPHA
 }