From: Mikko Rasa <tdb@tdb.fi>
Date: Fri, 1 Oct 2021 09:48:01 +0000 (+0300)
Subject: Add color write mask to blend state
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgl.git;a=commitdiff_plain;h=bae374a3cda6a1b59f36016624ef518bf2676355

Add color write mask to blend state
---

diff --git a/source/core/blend.cpp b/source/core/blend.cpp
index 324440d3..8ceb2382 100644
--- a/source/core/blend.cpp
+++ b/source/core/blend.cpp
@@ -1,6 +1,7 @@
 #include <msp/gl/extensions/ext_blend_minmax.h>
 #include <msp/gl/extensions/ext_blend_subtract.h>
 #include <msp/strings/format.h>
+#include <msp/strings/utils.h>
 #include "blend.h"
 
 using namespace std;
@@ -13,7 +14,8 @@ Blend::Blend():
 	equation(ADD),
 	src_factor(ONE),
 	dst_factor(ZERO),
-	constant(0.0f, 0.0f, 0.0f, 0.0f)
+	constant(0.0f, 0.0f, 0.0f, 0.0f),
+	write_mask(WRITE_ALL)
 { }
 
 Blend::Blend(BlendFactor sf, BlendFactor df):
@@ -21,7 +23,8 @@ Blend::Blend(BlendFactor sf, BlendFactor df):
 	equation(ADD),
 	src_factor(sf),
 	dst_factor(df),
-	constant(0.0f, 0.0f, 0.0f, 0.0f)
+	constant(0.0f, 0.0f, 0.0f, 0.0f),
+	write_mask(WRITE_ALL)
 { }
 
 Blend::Blend(BlendEquation e, BlendFactor sf, BlendFactor df):
@@ -29,7 +32,8 @@ Blend::Blend(BlendEquation e, BlendFactor sf, BlendFactor df):
 	equation(e),
 	src_factor(sf),
 	dst_factor(df),
-	constant(0.0f, 0.0f, 0.0f, 0.0f)
+	constant(0.0f, 0.0f, 0.0f, 0.0f),
+	write_mask(WRITE_ALL)
 { }
 
 
@@ -182,5 +186,47 @@ void operator<<(LexicalConverter &conv, BlendFactor factor)
 	}
 }
 
+void operator>>(const LexicalConverter &conv, ColorWriteMask &mask)
+{
+	ColorWriteMask result = WRITE_NONE;
+	for(const string &p: split(conv.get(), '_'))
+	{
+		if(p=="ALL")
+			result = result|WRITE_ALL;
+		else if(p=="RED")
+			result = result|WRITE_RED;
+		else if(p=="GREEN")
+			result = result|WRITE_GREEN;
+		else if(p=="BLUE")
+			result = result|WRITE_BLUE;
+		else if(p=="ALPHA")
+			result = result|WRITE_ALPHA;
+		else
+			throw lexical_error(format("conversion of '%s' to ColorWriteMask", conv.get()));
+	}
+	mask = result;
+}
+
+void operator<<(LexicalConverter &conv, ColorWriteMask mask)
+{
+	if(mask==WRITE_ALL)
+		conv.result("ALL");
+	else if(mask&~WRITE_ALL)
+		conv.result(format("ColorWriteMask(%#x)", static_cast<int>(mask)));
+	else
+	{
+		string result;
+		if(mask&WRITE_RED)
+			result = "RED";
+		if(mask&WRITE_GREEN)
+			append(result, "_", "GREEN");
+		if(mask&WRITE_BLUE)
+			append(result, "_", "BLUE");
+		if(mask&WRITE_ALPHA)
+			append(result, "_", "ALPHA");
+		conv.result(result);
+	}
+}
+
 } // namespace GL
 } // namespace Msp
diff --git a/source/core/blend.h b/source/core/blend.h
index ad7ba241..a1180050 100644
--- a/source/core/blend.h
+++ b/source/core/blend.h
@@ -35,6 +35,16 @@ enum BlendFactor
 	ONE_MINUS_CONSTANT_ALPHA
 };
 
+enum ColorWriteMask
+{
+	WRITE_NONE = 0,
+	WRITE_RED = 1,
+	WRITE_GREEN = 2,
+	WRITE_BLUE = 4,
+	WRITE_ALPHA = 8,
+	WRITE_ALL = 15
+};
+
 /**
 Blends incoming fragments with those already in the framebuffer.
 */
@@ -56,12 +66,17 @@ struct Blend
 	BlendFactor src_factor;
 	BlendFactor dst_factor;
 	Color constant;
+	ColorWriteMask write_mask;
 
 	Blend();
 	Blend(BlendFactor, BlendFactor);
 	Blend(BlendEquation, BlendFactor, BlendFactor);
 };
 
+
+inline ColorWriteMask operator|(ColorWriteMask m1, ColorWriteMask m2)
+{ return static_cast<ColorWriteMask>(static_cast<int>(m1)|static_cast<int>(m2)); }
+
 unsigned get_gl_blend_equation(BlendEquation);
 unsigned get_gl_blend_factor(BlendFactor);
 
@@ -71,6 +86,9 @@ void operator<<(LexicalConverter &, BlendEquation);
 void operator>>(const LexicalConverter &, BlendFactor &);
 void operator<<(LexicalConverter &, BlendFactor);
 
+void operator>>(const LexicalConverter &, ColorWriteMask &);
+void operator<<(LexicalConverter &, ColorWriteMask);
+
 } // namespace GL
 } // namespace Msp
 
diff --git a/source/core/pipelinestate.cpp b/source/core/pipelinestate.cpp
index 97f353dc..262dd26b 100644
--- a/source/core/pipelinestate.cpp
+++ b/source/core/pipelinestate.cpp
@@ -322,9 +322,14 @@ void PipelineState::apply(unsigned mask) const
 			glBlendEquation(get_gl_blend_equation(blend->equation));
 			glBlendFunc(get_gl_blend_factor(blend->src_factor), get_gl_blend_factor(blend->dst_factor));
 			glBlendColor(blend->constant.r, blend->constant.g, blend->constant.b, blend->constant.a);
+			ColorWriteMask cw = blend->write_mask;
+			glColorMask((cw&WRITE_RED)!=0, (cw&WRITE_GREEN)!=0, (cw&WRITE_BLUE)!=0, (cw&WRITE_ALPHA)!=0);
 		}
 		else
+		{
 			glDisable(GL_BLEND);
+			glColorMask(true, true, true, true);
+		}
 	}
 
 	last_applied = this;