From Pavel Moloshtan, added GL_ARB_shadow_support to osg::Texture.

include/osg/Texture

@@ -75,6 +75,11 @@
 #define GL_TEXTURE_3D                     0x806F
 #endif
 
+#ifndef GL_TEXTURE_COMPARE_MODE_ARB
+#define GL_TEXTURE_COMPARE_MODE_ARB       0x884C
+#define GL_TEXTURE_COMPARE_FUNC_ARB       0x884D
+#define GL_COMPARE_R_TO_TEXTURE_ARB       0x884E
+#endif
 
 
 namespace osg {
@@ -232,6 +237,29 @@ class SG_EXPORT Texture : public osg::StateAttribute
         void dirtyTextureParameters();
 
 
+        // set mode of GL_TEXTURE_COMPARE_MODE_ARB to GL_COMPARE_R_TO_TEXTURE_ARB
+        // See http://oss.sgi.com/projects/ogl-sample/registry/ARB/shadow.txt
+        void setShadowComparison(bool flag) { _use_shadow_comparison = flag; }
+
+        enum ShadowCompareFunc {
+            LEQUAL = GL_LEQUAL,
+            GEQUAL = GL_GEQUAL
+        };
+
+        // set shadow texture comparison function
+        void setShadowCompareFunc(ShadowCompareFunc func) { _shadow_compare_func = func; }
+        ShadowCompareFunc getShadowCompareFunc() { return _shadow_compare_func; }
+
+        enum ShadowTextureMode {
+            LUMINANCE = GL_LUMINANCE,
+            INTENSITY = GL_INTENSITY,
+            ALPHA = GL_ALPHA
+        };
+
+        // set shadow texture mode after comparison
+        void setShadowTextureMode(ShadowTextureMode mode) { _shadow_texture_mode = mode; }
+        ShadowTextureMode getShadowTextureMode() { return _shadow_texture_mode; }
+
 
         
         /** Texture is pure virtual base class, apply must be overriden. */
@@ -278,6 +306,9 @@ class SG_EXPORT Texture : public osg::StateAttribute
                 void setGenerateMipMapSupported(bool flag) { _isGenerateMipMapSupported=flag; }
                 bool isGenerateMipMapSupported() const { return _isGenerateMipMapSupported; }
 
+                void setShadowSupported(bool flag) { _isShadowSupported = flag; }
+                bool isShadowSupported() const { return _isShadowSupported; }
+
                 void setMaxTextureSize(GLint maxsize) { _maxTextureSize=maxsize; }
                 GLint maxTextureSize() const { return _maxTextureSize; }
 
@@ -304,6 +335,7 @@ class SG_EXPORT Texture : public osg::StateAttribute
                 bool    _isTextureEdgeClampSupported;
                 bool    _isTextureBorderClampSupported;
                 bool    _isGenerateMipMapSupported;
+                bool    _isShadowSupported;
                 
                 GLint   _maxTextureSize;
 
@@ -372,8 +404,11 @@ class SG_EXPORT Texture : public osg::StateAttribute
 
         InternalFormatMode  _internalFormatMode;
         mutable GLint       _internalFormat;
-        
-        
+      
+        bool                _use_shadow_comparison;
+        ShadowCompareFunc   _shadow_compare_func;
+        ShadowTextureMode   _shadow_texture_mode;
+
     public:
     
         class TextureObject : public osg::Referenced

src/osg/Texture.cpp

@@ -174,7 +174,10 @@ Texture::Texture():
             _unrefImageDataAfterApply(false),
             _borderColor(0.0, 0.0, 0.0, 0.0),
             _internalFormatMode(USE_IMAGE_DATA_FORMAT),
-            _internalFormat(0)
+            _internalFormat(0),
+            _use_shadow_comparison(false),
+            _shadow_compare_func(LEQUAL),
+            _shadow_texture_mode(LUMINANCE)
 {
 }
 
@@ -190,7 +193,10 @@ Texture::Texture(const Texture& text,const CopyOp& copyop):
             _unrefImageDataAfterApply(text._unrefImageDataAfterApply),
             _borderColor(text._borderColor),
             _internalFormatMode(text._internalFormatMode),
-            _internalFormat(text._internalFormat)
+            _internalFormat(text._internalFormat),
+            _use_shadow_comparison(text._use_shadow_comparison),
+            _shadow_compare_func(text._shadow_compare_func),
+            _shadow_texture_mode(text._shadow_texture_mode)
 {
 }
 
@@ -211,6 +217,9 @@ int Texture::compareTexture(const Texture& rhs) const
     COMPARE_StateAttribute_Parameter(_useHardwareMipMapGeneration)
     COMPARE_StateAttribute_Parameter(_internalFormatMode)
     COMPARE_StateAttribute_Parameter(_internalFormat)
+    COMPARE_StateAttribute_Parameter(_use_shadow_comparison)
+    COMPARE_StateAttribute_Parameter(_shadow_compare_func)
+    COMPARE_StateAttribute_Parameter(_shadow_texture_mode)
     
     return 0;
 }
@@ -474,6 +483,20 @@ void Texture::applyTexParameters(GLenum target, State& state) const
         glTexParameterfv(target, GL_TEXTURE_BORDER_COLOR, _borderColor.ptr());
     }
 
+    if (extensions->isShadowSupported() && target == GL_TEXTURE_2D)
+      {
+        if (_use_shadow_comparison)
+          {
+            glTexParameteri(target, GL_TEXTURE_COMPARE_MODE_ARB, GL_COMPARE_R_TO_TEXTURE);
+            glTexParameteri(target, GL_TEXTURE_COMPARE_FUNC_ARB, _shadow_compare_func);
+            glTexParameteri(target, GL_DEPTH_TEXTURE_MODE_ARB, _shadow_texture_mode);
+          }
+        else 
+          {
+            glTexParameteri(target, GL_TEXTURE_COMPARE_MODE_ARB, GL_NONE);
+          }
+      }
+
     getTextureParameterDirty(state.getContextID()) = false;
 
 }
@@ -1038,6 +1061,7 @@ void Texture::Extensions::setupGLExtenions()
     _isTextureBorderClampSupported = isGLExtensionSupported("GL_ARB_texture_border_clamp");
     _isGenerateMipMapSupported = (strncmp((const char*)glGetString(GL_VERSION),"1.4",3)>=0) ||
                                   isGLExtensionSupported("GL_SGIS_generate_mipmap");
+    _isShadowSupported = isGLExtensionSupported("GL_ARB_shadow");
 
 
     glGetIntegerv(GL_MAX_TEXTURE_SIZE,&_maxTextureSize);