Another exotic extension, which can be emulated by the new AMD extension as...

Another exotic extension, which can be emulated by the new AMD extension as well, but is mostly found on ancient SGI machines.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@3680 dfc29bdd-3216-0410-991c-e03cc46cb475

include/SMaterial.h

@@ -45,7 +45,9 @@ namespace video
 		EBO_MIN,		//!< Choose minimum value of each color channel
 		EBO_MAX,		//!< Choose maximum value of each color channel
 		EBO_MIN_FACTOR,	//!< Choose minimum value of each color channel after applying blend factors, not widely supported
-		EBO_MAX_FACTOR	//!< Choose maximum value of each color channel after applying blend factors, not widely supported
+		EBO_MAX_FACTOR,	//!< Choose maximum value of each color channel after applying blend factors, not widely supported
+		EBO_MIN_ALPHA,	//!< Choose minimum value of each color channel based on alpha value, not widely supported
+		EBO_MAX_ALPHA	//!< Choose maximum value of each color channel based on alpha value, not widely supported
 	};
 
 	//! MaterialTypeParam: e.g. DirectX: D3DTOP_MODULATE, D3DTOP_MODULATE2X, D3DTOP_MODULATE4X

source/Irrlicht/CD3D9Driver.cpp

@@ -2273,10 +2273,12 @@ void CD3D9Driver::setBasicRenderStates(const SMaterial& material, const SMateria
 				break;
 			case EBO_MIN:
 			case EBO_MIN_FACTOR:
+			case EBO_MIN_ALPHA:
 				pID3DDevice->SetRenderState(D3DRS_BLENDOP, D3DBLENDOP_MIN);
 				break;
 			case EBO_MAX:
 			case EBO_MAX_FACTOR:
+			case EBO_MAX_ALPHA:
 				pID3DDevice->SetRenderState(D3DRS_BLENDOP, D3DBLENDOP_MAX);
 				break;
 			default:

source/Irrlicht/COpenGLDriver.cpp

@@ -2994,6 +2994,26 @@ void COpenGLDriver::setBasicRenderStates(const SMaterial& material, const SMater
 #endif
 				if (Version>=120)
 					extGlBlendEquation(GL_MAX);
+#endif
+				break;
+			case EBO_MIN_ALPHA:
+#if defined(GL_SGIX_blend_alpha_minmax)
+				if (FeatureAvailable[IRR_SGIX_blend_alpha_minmax])
+					extGlBlendEquation(GL_ALPHA_MIN_SGIX);
+				// fallback in case of missing extension
+				else
+					if (FeatureAvailable[IRR_EXT_blend_minmax])
+						extGlBlendEquation(GL_MIN_EXT);
+#endif
+				break;
+			case EBO_MAX_ALPHA:
+#if defined(GL_SGIX_blend_alpha_minmax)
+				if (FeatureAvailable[IRR_SGIX_blend_alpha_minmax])
+					extGlBlendEquation(GL_ALPHA_MAX_SGIX);
+				// fallback in case of missing extension
+				else
+					if (FeatureAvailable[IRR_EXT_blend_minmax])
+						extGlBlendEquation(GL_MAX_EXT);
 #endif
 				break;
 			default:
@@ -4135,6 +4155,7 @@ bool COpenGLDriver::setRenderTarget(const core::array<video::IRenderTarget>& tar
 					extGlBlendEquationIndexed(i, GL_MAX);
 					break;
 				case EBO_MIN_FACTOR:
+				case EBO_MIN_ALPHA:
 #if defined(GL_AMD_blend_minmax_factor)
 					if (FeatureAvailable[IRR_AMD_blend_minmax_factor])
 						extGlBlendEquationIndexed(i, GL_FACTOR_MIN_AMD);
@@ -4144,6 +4165,7 @@ bool COpenGLDriver::setRenderTarget(const core::array<video::IRenderTarget>& tar
 						extGlBlendEquation(GL_MIN);
 					break;
 				case EBO_MAX_FACTOR:
+				case EBO_MAX_ALPHA:
 #if defined(GL_AMD_blend_minmax_factor)
 					if (FeatureAvailable[IRR_AMD_blend_minmax_factor])
 						extGlBlendEquationIndexed(i, GL_FACTOR_MAX_AMD);