Game Engine: alpha blending and sorting

=======================================

Alpha blending + sorting was revised, to fix bugs and get it
to work more predictable.

* A new per texture face "Sort" setting defines if the face
  is alpha sorted or not, instead of abusing the "ZTransp"
  setting as it did before.
* Existing files are converted to hopefully match the old
  behavior as much as possible with a version patch.
* On new meshes the Sort flag is disabled by the default, to
  avoid unexpected and hard to find slowdowns.
* Alpha sorting for faces was incredibly slow. Sorting faces
  in a mesh with 600 faces lowered the framerate from 200 to
  70 fps in my test.. the sorting there case goes about 15x
  faster now, but it is still advised to use Clip Alpha if
  possible instead of regular Alpha.
* There still various limitations in the alpha sorting code,
  I've added some comments to the code about this.

Some docs at the bottom of the page:
http://www.blender.org/development/current-projects/changes-since-246/realtime-glsl-materials/

Merged some fixes from the apricot branch, most important
change is that  tangents are now exactly the same as the rest
of Blender, instead of being computed in the game engine with a
different algorithm.

Also, the subversion was bumped to 1.

1 files changed, 36 insertions, 12 deletions

diff --git a/source/gameengine/Rasterizer/RAS_OpenGLRasterizer/RAS_OpenGLRasterizer.cpp b/source/gameengine/Rasterizer/RAS_OpenGLRasterizer/RAS_OpenGLRasterizer.cpp
index dcc36bf5a39..1dcc6e70934 100644
--- a/source/gameengine/Rasterizer/RAS_OpenGLRasterizer/RAS_OpenGLRasterizer.cpp
+++ b/source/gameengine/Rasterizer/RAS_OpenGLRasterizer/RAS_OpenGLRasterizer.cpp
@@ -67,6 +67,7 @@ RAS_OpenGLRasterizer::RAS_OpenGLRasterizer(RAS_ICanvas* canvas)
 	m_motionblurvalue(-1.0),
 	m_texco_num(0),
 	m_attrib_num(0),
+	m_last_blendmode(0),
 	m_materialCachingInfo(0)
 {
 	m_viewmatrix.Identity();
@@ -171,6 +172,8 @@ bool RAS_OpenGLRasterizer::Init()
 	m_ambg = 0.0f;
 	m_ambb = 0.0f;
 
+	SetBlendingMode(0);
+
 	glClearColor(m_redback,m_greenback,m_blueback,m_alphaback);
 	glColorMask(GL_TRUE, GL_TRUE, GL_TRUE, GL_TRUE);
 	glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
@@ -189,18 +192,6 @@ void RAS_OpenGLRasterizer::SetAmbientColor(float red, float green, float blue)
 }
 
 
-void RAS_OpenGLRasterizer::SetAlphaTest(bool enable)
-{
-	if (enable)
-	{
-		glEnable(GL_ALPHA_TEST);
-		glAlphaFunc(GL_GREATER, 0.6f);
-	}
-	else glDisable(GL_ALPHA_TEST);
-}
-
-
-
 void RAS_OpenGLRasterizer::SetAmbient(float factor)
 {
 	float ambient[] = { m_ambr*factor, m_ambg*factor, m_ambb*factor, 1.0f };
@@ -353,6 +344,8 @@ bool RAS_OpenGLRasterizer::BeginFrame(int drawingmode, double time)
 		glEnable (GL_CULL_FACE);
 	}
 
+	SetBlendingMode(0);
+
 	glShadeModel(GL_SMOOTH);
 
 	m_2DCanvas->BeginFrame();
@@ -1389,3 +1382,34 @@ void RAS_OpenGLRasterizer::DisableMotionBlur()
 	m_motionblur = 0;
 	m_motionblurvalue = -1.0;
 }
+
+void RAS_OpenGLRasterizer::SetBlendingMode(int blendmode)
+{
+	if(blendmode == m_last_blendmode)
+		return;
+
+	if(blendmode == 0) {
+		glDisable(GL_BLEND);
+		glDisable(GL_ALPHA_TEST);
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+	}
+	else if(blendmode == 1) {
+		glBlendFunc(GL_ONE, GL_ONE);
+		glEnable(GL_BLEND);
+		glDisable(GL_ALPHA_TEST);
+	}
+	else if(blendmode == 2) {
+		glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
+		glEnable(GL_BLEND);
+		glEnable(GL_ALPHA_TEST);
+		glAlphaFunc(GL_GREATER, 0.0f);
+	}
+	else if(blendmode == 4) {
+		glDisable(GL_BLEND); 
+		glEnable(GL_ALPHA_TEST);
+		glAlphaFunc(GL_GREATER, 0.5f);
+	}
+
+	m_last_blendmode = blendmode;
+}
+