BGE: Setting up the RAS_ICanvas interface as the primary way to alter the OpenGL

viewport. This helps to eliminate OpenGL calls in weird places like the physics
code and to reduce glGet calls, which are expensive.

There should be no functional changes (except maybe a very slight speed improvement).

2 files changed, 25 insertions, 0 deletions

diff --git a/source/gameengine/GamePlayer/common/GPC_Canvas.cpp b/source/gameengine/GamePlayer/common/GPC_Canvas.cpp
index 7581484a41f..b5c1c29238a 100644
--- a/source/gameengine/GamePlayer/common/GPC_Canvas.cpp
+++ b/source/gameengine/GamePlayer/common/GPC_Canvas.cpp
@@ -57,6 +57,8 @@ GPC_Canvas::GPC_Canvas(
 	m_displayarea.m_y1 = 0;
 	m_displayarea.m_x2 = width;
 	m_displayarea.m_y2 = height;
+
+	glGetIntegerv(GL_VIEWPORT, (GLint*)m_viewport);
 }
 
 
@@ -121,11 +123,31 @@ void GPC_Canvas::SetViewPort(int x1, int y1, int x2, int y2)
 		 * whole canvas/rendertools mess.
 		 */
 	glEnable(GL_SCISSOR_TEST);
+	
+	m_viewport[0] = x1;
+	m_viewport[1] = y1;
+	m_viewport[2] = x2-x1 + 1;
+	m_viewport[3] = y2-y1 + 1;
 
 	glViewport(x1,y1,x2-x1 + 1,y2-y1 + 1);
 	glScissor(x1,y1,x2-x1 + 1,y2-y1 + 1);
 };
 
+const int *GPC_Canvas::GetViewPort()
+{
+#ifdef DEBUG
+	// If we're in a debug build, we might as well make sure our values don't differ
+	// from what the gpu thinks we have. This could lead to nasty, hard to find bugs.
+	int viewport[4];
+	glGetIntegerv(GL_VIEWPORT, viewport);
+	assert(viewport[0] == m_viewport[0]);
+	assert(viewport[1] == m_viewport[1]);
+	assert(viewport[2] == m_viewport[2]);
+	assert(viewport[3] == m_viewport[3]);
+#endif
+
+	return m_viewport;
+}
 
 void GPC_Canvas::ClearBuffer(
 	int type
diff --git a/source/gameengine/GamePlayer/common/GPC_Canvas.h b/source/gameengine/GamePlayer/common/GPC_Canvas.h
index 453b9505183..2a597c4c43d 100644
--- a/source/gameengine/GamePlayer/common/GPC_Canvas.h
+++ b/source/gameengine/GamePlayer/common/GPC_Canvas.h
@@ -90,6 +90,8 @@ protected:
 	 * relative to the context */
 	RAS_Rect m_displayarea;
 
+	int *m_viewport;
+
 	/** Storage for the banners to display. */
 	TBannerMap m_banners;
 	/** State of banner display. */
@@ -153,6 +155,7 @@ public:
 	);
 	
 	void SetViewPort(int x1, int y1, int x2, int y2);
+	const int *GetViewPort();
 
 	void ClearColor(float r, float g, float b, float a);