From aed3339e43dbf7f1e22c5c6e0cdc16ad50cf32c9 Mon Sep 17 00:00:00 2001
From: Robert Osfield <robert@openscenegraph.com>
Date: Fri, 30 Jan 2009 18:56:30 +0000
Subject: [PATCH] Improved shaders to better handle region of constant values
 when doing normal generation

---
 src/osgVolume/Shaders/volume_frag.cpp        |  3 +-
 src/osgVolume/Shaders/volume_iso_frag.cpp    | 31 +++++++-------------
 src/osgVolume/Shaders/volume_lit_frag.cpp    | 18 +++++++-----
 src/osgVolume/Shaders/volume_lit_tf_frag.cpp | 16 +++++-----
 src/osgVolume/Shaders/volume_mip_frag.cpp    |  3 +-
 src/osgVolume/Shaders/volume_tf_frag.cpp     |  3 +-
 src/osgVolume/Shaders/volume_tf_iso_frag.cpp |  3 +-
 src/osgVolume/Shaders/volume_tf_mip_frag.cpp |  3 +-
 8 files changed, 35 insertions(+), 45 deletions(-)

diff --git a/src/osgVolume/Shaders/volume_frag.cpp b/src/osgVolume/Shaders/volume_frag.cpp
index 1cc4cfb90..d2e97f362 100644
--- a/src/osgVolume/Shaders/volume_frag.cpp
+++ b/src/osgVolume/Shaders/volume_frag.cpp
@@ -95,5 +95,4 @@ char volume_frag[] = "uniform sampler3D baseTexture;\n"
                      "    if (fragColor.w<AlphaFuncValue) discard;\n"
                      "    \n"
                      "    gl_FragColor = fragColor;\n"
-                     "}\n"
-                     "\n";
+                     "}\n";
diff --git a/src/osgVolume/Shaders/volume_iso_frag.cpp b/src/osgVolume/Shaders/volume_iso_frag.cpp
index 154439192..692ffed17 100644
--- a/src/osgVolume/Shaders/volume_iso_frag.cpp
+++ b/src/osgVolume/Shaders/volume_iso_frag.cpp
@@ -72,7 +72,6 @@ char volume_iso_frag[] = "uniform sampler3D baseTexture;\n"
                          "    vec3 deltaTexCoord=(t0-te)/float(num_iterations-1.0);\n"
                          "    vec3 texcoord = te;\n"
                          "\n"
-                         "    vec4 fragColor = vec4(0.0, 0.0, 0.0, 0.0);    \n"
                          "    vec4 previousColor = texture3D( baseTexture, texcoord);\n"
                          "    \n"
                          "    float normalSampleDistance = 1.0/512.0;\n"
@@ -100,25 +99,18 @@ char volume_iso_frag[] = "uniform sampler3D baseTexture;\n"
                          "            float nz = texture3D( baseTexture, texcoord - deltaZ).a;\n"
                          "            \n"
                          "            vec3 grad = vec3(px-nx, py-ny, pz-nz);\n"
-                         "            vec3 normal = normalize(grad);\n"
+                         "            if (grad.x!=0.0 || grad.y!=0.0 || grad.z!=0.0)\n"
+                         "            {\n"
+                         "                vec3 normal = normalize(grad);\n"
+                         "                float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection))*0.9;\n"
                          "\n"
-                         "            float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection))*0.9;\n"
+                         "                color.x *= lightScale;\n"
+                         "                color.y *= lightScale;\n"
+                         "                color.z *= lightScale;\n"
+                         "            }\n"
                          "            \n"
-                         "            \n"
-                         "#if 0\n"
-                         "            color.x *= lightScale;\n"
-                         "            color.y *= lightScale;\n"
-                         "            color.z *= lightScale;\n"
-                         "#else\n"
-                         "            color.x = lightScale;\n"
-                         "            color.y = lightScale;\n"
-                         "            color.z = lightScale;\n"
-                         "#endif\n"
-                         "\n"
-                         "            fragColor = vec4(lightScale, lightScale, lightScale, 1.0);\n"
-                         "            \n"
-                         "            if (fragColor.w>1.0) fragColor.w = 1.0; \n"
-                         "            gl_FragColor = fragColor;\n"
+                         "            if (color.w>1.0) color.w = 1.0; \n"
+                         "            gl_FragColor = color;\n"
                          "            \n"
                          "            return;\n"
                          "        }\n"
@@ -132,5 +124,4 @@ char volume_iso_frag[] = "uniform sampler3D baseTexture;\n"
                          "\n"
                          "    // we didn't find an intersection so just discard fragment\n"
                          "    discard;\n"
-                         "}\n"
-                         "\n";
+                         "}\n";
diff --git a/src/osgVolume/Shaders/volume_lit_frag.cpp b/src/osgVolume/Shaders/volume_lit_frag.cpp
index 647ab5217..cb2ca122a 100644
--- a/src/osgVolume/Shaders/volume_lit_frag.cpp
+++ b/src/osgVolume/Shaders/volume_lit_frag.cpp
@@ -80,6 +80,7 @@ char volume_lit_frag[] = "uniform sampler3D baseTexture;\n"
                          "    while(num_iterations>0.0)\n"
                          "    {\n"
                          "        vec4 color = texture3D( baseTexture, texcoord);\n"
+                         "\n"
                          "        float a = color.a;\n"
                          "        float px = texture3D( baseTexture, texcoord + deltaX).a;\n"
                          "        float py = texture3D( baseTexture, texcoord + deltaY).a;\n"
@@ -90,13 +91,15 @@ char volume_lit_frag[] = "uniform sampler3D baseTexture;\n"
                          "        float nz = texture3D( baseTexture, texcoord - deltaZ).a;\n"
                          "\n"
                          "        vec3 grad = vec3(px-nx, py-ny, pz-nz);\n"
-                         "        vec3 normal = normalize(grad);\n"
+                         "        if (grad.x!=0.0 || grad.y!=0.0 || grad.z!=0.0)\n"
+                         "        {\n"
+                         "            vec3 normal = normalize(grad);\n"
+                         "            float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection))*0.9;\n"
                          "\n"
-                         "        float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection));\n"
-                         "\n"
-                         "        color.x *= lightScale;\n"
-                         "        color.y *= lightScale;\n"
-                         "        color.z *= lightScale;\n"
+                         "            color.x *= lightScale;\n"
+                         "            color.y *= lightScale;\n"
+                         "            color.z *= lightScale;\n"
+                         "        }\n"
                          "\n"
                          "        float r = color[3]*TransparencyValue;\n"
                          "        if (r>AlphaFuncValue)\n"
@@ -120,5 +123,4 @@ char volume_lit_frag[] = "uniform sampler3D baseTexture;\n"
                          "    if (fragColor.w<AlphaFuncValue) discard;\n"
                          "    \n"
                          "    gl_FragColor = fragColor;\n"
-                         "}\n"
-                         "\n";
+                         "}\n";
diff --git a/src/osgVolume/Shaders/volume_lit_tf_frag.cpp b/src/osgVolume/Shaders/volume_lit_tf_frag.cpp
index 9d7ab6265..6ed289510 100644
--- a/src/osgVolume/Shaders/volume_lit_tf_frag.cpp
+++ b/src/osgVolume/Shaders/volume_lit_tf_frag.cpp
@@ -93,13 +93,16 @@ char volume_lit_tf_frag[] = "uniform sampler3D baseTexture;\n"
                             "        float nz = texture3D( baseTexture, texcoord - deltaZ).a;\n"
                             "\n"
                             "        vec3 grad = vec3(px-nx, py-ny, pz-nz);\n"
-                            "        vec3 normal = normalize(grad);\n"
+                            "        if (grad.x!=0.0 || grad.y!=0.0 || grad.z!=0.0)\n"
+                            "        {\n"
+                            "            vec3 normal = normalize(grad);\n"
+                            "            float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection))*0.9;\n"
                             "\n"
-                            "        float lightScale = 0.1 +  abs(dot(normal.xyz, eyeDirection));\n"
+                            "            color.x *= lightScale;\n"
+                            "            color.y *= lightScale;\n"
+                            "            color.z *= lightScale;\n"
+                            "        }\n"
                             "\n"
-                            "        color.x *= lightScale;\n"
-                            "        color.y *= lightScale;\n"
-                            "        color.z *= lightScale;\n"
                             "\n"
                             "        float r = color[3]*TransparencyValue;\n"
                             "        if (r>AlphaFuncValue)\n"
@@ -123,5 +126,4 @@ char volume_lit_tf_frag[] = "uniform sampler3D baseTexture;\n"
                             "    if (fragColor.w<AlphaFuncValue) discard;\n"
                             "    \n"
                             "    gl_FragColor = fragColor;\n"
-                            "}\n"
-                            "\n";
+                            "}\n";
diff --git a/src/osgVolume/Shaders/volume_mip_frag.cpp b/src/osgVolume/Shaders/volume_mip_frag.cpp
index c536d8289..707a3a46d 100644
--- a/src/osgVolume/Shaders/volume_mip_frag.cpp
+++ b/src/osgVolume/Shaders/volume_mip_frag.cpp
@@ -88,5 +88,4 @@ char volume_mip_frag[] = "uniform sampler3D baseTexture;\n"
                          "    if (fragColor.w<AlphaFuncValue) discard;\n"
                          "    \n"
                          "    gl_FragColor = fragColor;\n"
-                         "}\n"
-                         "\n";
+                         "}\n";
diff --git a/src/osgVolume/Shaders/volume_tf_frag.cpp b/src/osgVolume/Shaders/volume_tf_frag.cpp
index f068dd4a4..c3f9517f0 100644
--- a/src/osgVolume/Shaders/volume_tf_frag.cpp
+++ b/src/osgVolume/Shaders/volume_tf_frag.cpp
@@ -98,5 +98,4 @@ char volume_tf_frag[] = "uniform sampler3D baseTexture;\n"
                         "    if (fragColor.w<AlphaFuncValue) discard;\n"
                         "    \n"
                         "    gl_FragColor = fragColor;\n"
-                        "}\n"
-                        "\n";
+                        "}\n";
diff --git a/src/osgVolume/Shaders/volume_tf_iso_frag.cpp b/src/osgVolume/Shaders/volume_tf_iso_frag.cpp
index 016694a6f..caa5f4c91 100644
--- a/src/osgVolume/Shaders/volume_tf_iso_frag.cpp
+++ b/src/osgVolume/Shaders/volume_tf_iso_frag.cpp
@@ -126,5 +126,4 @@ char volume_tf_iso_frag[] = "uniform sampler3D baseTexture;\n"
                             "   // we didn't find an intersection so just discard fragment\n"
                             "   discard;\n"
                             "\n"
-                            "}\n"
-                            "\n";
+                            "}\n";
diff --git a/src/osgVolume/Shaders/volume_tf_mip_frag.cpp b/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
index 49ef80443..4c208c128 100644
--- a/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
+++ b/src/osgVolume/Shaders/volume_tf_mip_frag.cpp
@@ -89,5 +89,4 @@ char volume_tf_mip_frag[] = "uniform sampler3D baseTexture;\n"
                             "    if (fragColor.w>1.0) fragColor.w = 1.0; \n"
                             "    if (fragColor.w<AlphaFuncValue) discard;\n"
                             "    gl_FragColor = fragColor;\n"
-                            "}\n"
-                            "\n";
+                            "}\n";