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, 27 insertions, 0 deletions

diff --git a/source/gameengine/BlenderRoutines/KX_BlenderCanvas.cpp b/source/gameengine/BlenderRoutines/KX_BlenderCanvas.cpp
index 4f450bcd668..0b41cceb646 100644
--- a/source/gameengine/BlenderRoutines/KX_BlenderCanvas.cpp
+++ b/source/gameengine/BlenderRoutines/KX_BlenderCanvas.cpp
@@ -33,6 +33,7 @@
 #include "KX_BlenderCanvas.h"
 #include "DNA_screen_types.h"
 #include <stdio.h>
+#include <assert.h>
 
 
 KX_BlenderCanvas::KX_BlenderCanvas(struct wmWindow *win, RAS_Rect &rect, struct ARegion *ar) :
@@ -44,6 +45,8 @@ m_frame_rect(rect)
 	// area boundaries needed for mouse coordinates in Letterbox framing mode
 	m_area_left = ar->winrct.xmin;
 	m_area_top = ar->winrct.ymax;
+
+	glGetIntegerv(GL_VIEWPORT, (GLint*)m_viewport);
 }
 
 KX_BlenderCanvas::~KX_BlenderCanvas()
@@ -166,10 +169,31 @@ SetViewPort(
 	m_area_rect.SetRight(minx + x2);
 	m_area_rect.SetTop(miny + y2);
 
+	m_viewport[0] = minx+x1;
+	m_viewport[1] = miny+y1;
+	m_viewport[2] = vp_width;
+	m_viewport[3] = vp_height;
+
 	glViewport(minx + x1, miny + y1, vp_width, vp_height);
 	glScissor(minx + x1, miny + y1, vp_width, vp_height);
 }
 
+	const int*
+KX_BlenderCanvas::
+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 KX_BlenderCanvas::SetMouseState(RAS_MouseState mousestate)
 {
diff --git a/source/gameengine/BlenderRoutines/KX_BlenderCanvas.h b/source/gameengine/BlenderRoutines/KX_BlenderCanvas.h
index ee7997abb39..004f7dd0dd9 100644
--- a/source/gameengine/BlenderRoutines/KX_BlenderCanvas.h
+++ b/source/gameengine/BlenderRoutines/KX_BlenderCanvas.h
@@ -61,6 +61,7 @@ private:
 	/** Rect that defines the area used for rendering,
 	    relative to the context */
 	RAS_Rect m_displayarea;
+	int m_viewport[4];
 
 public:
 	/* Construct a new canvas.
@@ -150,6 +151,8 @@ public:
 		int x1, int y1,
 		int x2, int y2
 	);
+		const int*
+	GetViewPort();
 
 		void 
 	SetMouseState(