diff --git a/src/osgVolume/Shaders/volume_tf_mip_frag.cpp b/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
index 059b1fee4..4fc50b798 100644
--- a/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
+++ b/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
@@ -14,9 +14,9 @@ char volume_tf_mip_frag[] = "uniform sampler3D baseTexture;\n"
                             "varying vec4 baseColor;\n"
                             "\n"
                             "void main(void)\n"
-                            "{ \n"
-                            "    vec3 t0 = (texgen * vertexPos).xyz;\n"
-                            "    vec3 te = (texgen * cameraPos).xyz;\n"
+                            "{\n"
+                            "    vec4 t0 = vertexPos;\n"
+                            "    vec4 te = cameraPos;\n"
                             "\n"
                             "    if (te.x>=0.0 && te.x<=1.0 &&\n"
                             "        te.y>=0.0 && te.y<=1.0 &&\n"
@@ -63,19 +63,22 @@ char volume_tf_mip_frag[] = "uniform sampler3D baseTexture;\n"
                             "        }\n"
                             "    }\n"
                             "\n"
+                            "    t0 = t0 * texgen;\n"
+                            "    te = te * texgen;\n"
+                            "\n"
                             "    const float max_iteratrions = 2048.0;\n"
-                            "    float num_iterations = ceil(length(te-t0)/SampleDensityValue);\n"
+                            "    float num_iterations = ceil(length((te-t0).xyz)/SampleDensityValue);\n"
                             "    if (num_iterations<2.0) num_iterations = 2.0;\n"
-                            "    \n"
-                            "    if (num_iterations>max_iteratrions) \n"
+                            "\n"
+                            "    if (num_iterations>max_iteratrions)\n"
                             "    {\n"
                             "        num_iterations = max_iteratrions;\n"
                             "    }\n"
                             "\n"
-                            "    vec3 deltaTexCoord=(te-t0)/float(num_iterations-1.0);\n"
-                            "    vec3 texcoord = t0;\n"
+                            "    vec3 deltaTexCoord=(te-t0).xyz/float(num_iterations-1.0);\n"
+                            "    vec3 texcoord = t0.xyz;\n"
                             "\n"
-                            "    vec4 fragColor = vec4(0.0, 0.0, 0.0, 0.0); \n"
+                            "    vec4 fragColor = vec4(0.0, 0.0, 0.0, 0.0);\n"
                             "    while(num_iterations>0.0)\n"
                             "    {\n"
                             "        float v = texture3D( baseTexture, texcoord).s * tfScale + tfOffset;\n"
@@ -84,7 +87,7 @@ char volume_tf_mip_frag[] = "uniform sampler3D baseTexture;\n"
                             "        {\n"
                             "            fragColor = color;\n"
                             "        }\n"
-                            "        texcoord += deltaTexCoord; \n"
+                            "        texcoord += deltaTexCoord;\n"
                             "\n"
                             "        --num_iterations;\n"
                             "    }\n"