[aquaria] Patch to fix water surface rendering glitch

[Andrew Church]

Quick fix for a bug reported on the Aquaria support forum
(http://www.bit-blot.com/forum/index.php?topic=778.0); it turns out the
calculations for frame buffer texture coordinates got thrown off if the
frame buffer height was not 1024 pixels.  I'll admit I haven't studied
the algorithm enough to know exactly where all the magic numbers come
from (: but I've checked that the texture coordinates from the new code
match those from the old code to 6 decimal places at 800x600 and 1024x768.

  --Andrew Church
    achurch at achurch.org
    http://achurch.org/

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# HG changeset patch
# User achurch
# Date 1280739646 -32400
# Branch water-surface-hi-res-glitch-fix
# Node ID 2d74c5dbf92dd986520cbd0211bf764100607663
# Parent  f08314f4174e071225534ab2922d22ff56cdf01b
Fix a rendering glitch on the water surface at high resolutions.

This patch fixes a rendering glitch reported on the Bit Blot forums
(http://www.bit-blot.com/forum/index.php?topic=778.0), in which the
water surface reflection was not properly rendered when the height of
the game window exceeded 1024 pixels.  (The glitch could also be seen
with a height of 512 pixels or less, such as at 640x480.)

diff -r f08314f4174e -r 2d74c5dbf92d Aquaria/WaterSurfaceRender.cpp
--- a/Aquaria/WaterSurfaceRender.cpp	Sat Jul 10 15:04:54 2010 +0900
+++ b/Aquaria/WaterSurfaceRender.cpp	Mon Aug 02 18:00:46 2010 +0900
@@ -201,18 +201,16 @@
 
 	if (dsq->useFrameBuffer && dsq->frameBuffer.isInited())
 	{
-		int scrh=0;
-		scrh = 768;
-		float factor = core->frameBuffer.getHeight()/float(scrh);
+		const float reflectSize = 97;
+		const float reflectPos = (dsq->game->waterLevel.x - core->cameraPos.y)
+				+ (dsq->game->waterLevel.x - core->screenCenter.y) / 3;
+		const float reflectOffset = -0.03f;
+		const float coordDiv = 768;
+		const float v0 = 1 + reflectOffset - (reflectPos * core->globalScale.x) / coordDiv;
+		const float v1 = v0 + (reflectSize * core->globalScale.x) / coordDiv;
 
-		float diff = (dsq->game->waterLevel.x - core->screenCenter.y)*factor + (core->screenCenter.y-core->cameraPos.y);
-
-		float tehSz = 97;
-		float psy1 = (tehSz/100.0)-(diff/float(scrh*core->invGlobalScale));
-		float bit = (tehSz/float(scrh*core->invGlobalScale));
-		
-		upperLeftTextureCoordinates.y = (psy1*core->frameBuffer.getHeightP());
-		lowerRightTextureCoordinates.y = (psy1*core->frameBuffer.getHeightP() + bit*core->frameBuffer.getHeightP());
+		upperLeftTextureCoordinates.y = v0 * core->frameBuffer.getHeightP();
+		lowerRightTextureCoordinates.y = v1 * core->frameBuffer.getHeightP();
 
 		upperLeftTextureCoordinates.x = 0;
 		lowerRightTextureCoordinates.x = core->frameBuffer.getWidthP();