Use square tree textures with reduce UV coordinates.

Shaders/deferred-tree.vert

@@ -11,9 +11,10 @@ void main() {
 
     // Texture coordinates
     float numVarieties = gl_Normal.z;
-		float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / (numVarieties * 4.0);
-		texFract += floor(gl_MultiTexCoord0.x) / (numVarieties * 4.0);
-    gl_TexCoord[0] = vec4(texFract + 0.5 * float(season), gl_MultiTexCoord0.y, 0.0, 0.0);  
+    float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties;
+    texFract += floor(gl_MultiTexCoord0.x) / numVarieties;
+    gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0);  
+    gl_TexCoord[0].y =  gl_TexCoord[0].y + 0.5 * season;
     
     // Position and scaling
     vec3 position = gl_Vertex.xyz * gl_Normal.xxy;

Shaders/tree-haze.vert

@@ -75,17 +75,18 @@ void main()
 // this code is copied from tree.vert
 
   float numVarieties = gl_Normal.z;
-  float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / (numVarieties * 4.0);
-  texFract += floor(gl_MultiTexCoord0.x) / (numVarieties * 4.0);
+  float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties;
+  texFract += floor(gl_MultiTexCoord0.x) / numVarieties;
   
   // Determine the rotation for the tree.  The Fog Coordinate provides rotation information
   // to rotate one of the quands by 90 degrees.  We then apply an additional position seed
   // so that trees aren't all oriented N/S
   float sr = sin(gl_FogCoord + gl_Color.x);
   float cr = cos(gl_FogCoord + gl_Color.x);
+  gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0);
   
-  // Shift texture to account for snow level and seasons
-  gl_TexCoord[0] = vec4(texFract + 0.25 * step(snow_level, gl_Color.z) + 0.5 * float(season), gl_MultiTexCoord0.y, 0.0, 0.0);
+  // Determine the y texture coordinate based on whether it's summer, winter, snowy.
+  gl_TexCoord[0].y =  gl_TexCoord[0].y + 0.25 * step(snow_level, gl_Color.z) + 0.5 * season;
 
   // scaling
   vec3 position = gl_Vertex.xyz * gl_Normal.xxy;

Shaders/tree.vert

@@ -17,15 +17,16 @@ uniform int season;
 void main(void)
 {
   float numVarieties = gl_Normal.z;
-  float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / (numVarieties * 4.0);
-  texFract += floor(gl_MultiTexCoord0.x) / (numVarieties * 4.0);
+  float texFract = floor(fract(gl_MultiTexCoord0.x) * numVarieties) / numVarieties;
+  texFract += floor(gl_MultiTexCoord0.x) / numVarieties;
   
   // Determine the rotation for the tree.  The Fog Coordinate provides rotation information
   // to rotate one of the quands by 90 degrees.  We then apply an additional position seed
   // so that trees aren't all oriented N/S
   float sr = sin(gl_FogCoord + gl_Color.x);
   float cr = cos(gl_FogCoord + gl_Color.x);
-  gl_TexCoord[0] = vec4(texFract + 0.5 * float(season), gl_MultiTexCoord0.y, 0.0, 0.0);
+  gl_TexCoord[0] = vec4(texFract, gl_MultiTexCoord0.y, 0.0, 0.0);
+  gl_TexCoord[0].y =  gl_TexCoord[0].y + 0.5 * season;
 
   // scaling
   vec3 position = gl_Vertex.xyz * gl_Normal.xxy;