1 files changed, 39 insertions, 0 deletions
diff --git a/Runtime/GfxDevice/VramLimits.cpp b/Runtime/GfxDevice/VramLimits.cpp
new file mode 100644
index 0000000..36bfe50
--- /dev/null
+++ b/Runtime/GfxDevice/VramLimits.cpp
@@ -0,0 +1,39 @@
+#include "UnityPrefix.h"
+#include "VramLimits.h"
+#include "Runtime/Shaders/GraphicsCaps.h"
+
+
+int ChooseSuitableFSAALevel( int width, int height, int backbufferBPP, int frontbufferBPP, int depthBPP, int fsaa )
+{
+	// no AA support?
+	if( !gGraphicsCaps.hasMultiSample )
+		return 0;
+
+	// figure out appropriate AA level based on VRAM and screen size
+	int vramKB = int(gGraphicsCaps.videoMemoryMB * 1024);
+
+	const int vramAllowedByPortion = int(vramKB * 0.5f); // allow max. 50% of total VRAM for screen
+	const int vramAllowedMax = 256 * 1024; // max 256MB for screen
+	// Make sure at least this amount of free of VRAM left after the screen.
+	// E.g. on a 32MB VRAM PPC MacMini, going 1280x960 2xAA still corrupts the screen (VRAM taken: 23.5MB).
+	// So we need to keep somewhat more free than 8MB... 16MB works.
+	const int vramAllowedWithKeepingSomeFree = int(vramKB - 16*1024);
+
+	int vramAllowedKB = std::min(vramAllowedByPortion, std::min(vramAllowedMax,vramAllowedWithKeepingSomeFree));
+	int vramNeededKB;
+	do {
+		vramNeededKB = width * height * (std::max(fsaa,1) * (backbufferBPP+depthBPP) + frontbufferBPP) / 1024;
+		if( vramNeededKB < vramAllowedKB )
+			break;
+
+		#if !UNITY_RELEASE
+		printf_console("Screen %ix%i at %ixAA won't fit, reducing AA (needed mem=%i allowedmem=%i)\n", width, height, fsaa, vramNeededKB, vramAllowedKB );
+		#endif
+		fsaa /= 2;
+	} while( fsaa > 1 );
+
+	if( fsaa == 1 )
+		fsaa = 0;
+
+	return fsaa;
+}