OpenGL render targets are now the same way up as in the other drivers. When...

OpenGL render targets are now the same way up as in the other drivers. When setting the projection matrix of a render target, the Y axis is flipped and polygon winding is switched to counter-clockwise.

git-svn-id: svn://svn.code.sf.net/p/irrlicht/code/trunk@787 dfc29bdd-3216-0410-991c-e03cc46cb475

changes.txt

 Changes in version 1.4 (... 2007)
 
+ - OpenGL render targets now the same way up as the other drivers. If you have
+   written opengl shaders that use render targets then you'll need to change your 
+   texture coordinates accordingly.
+
  - Fixed some OpenGL renderstate stuff. setBasicRenderstate returns with
    active texture layer 0. The material renderer must return from OnUnset
    with the same active texture layer. The alpha test is disabled and the

source/Irrlicht/COpenGLDriver.cpp

@@ -34,7 +34,7 @@ COpenGLDriver::COpenGLDriver(const core::dimension2d<s32>& screenSize, HWND wind
 : CNullDriver(io, screenSize), COpenGLExtensionHandler(),
 	CurrentRenderMode(ERM_NONE), ResetRenderStates(true), Transformation3DChanged(true),
 	AntiAlias(antiAlias), RenderTargetTexture(0), LastSetLight(-1),
-	CurrentRendertargetSize(0,0),
+	CurrentRendertargetSize(0,0), ClockwiseWinding(true),
 	HDc(0), Window(window), HRc(0)
 {
 	#ifdef _DEBUG
@@ -157,7 +157,7 @@ COpenGLDriver::COpenGLDriver(const core::dimension2d<s32>& screenSize, bool full
 : CNullDriver(io, screenSize), COpenGLExtensionHandler(),
 	CurrentRenderMode(ERM_NONE), ResetRenderStates(true), Transformation3DChanged(true),
 	AntiAlias(antiAlias),
-	RenderTargetTexture(0), LastSetLight(-1),
+	LastSetLight(-1), RenderTargetTexture(0), ClockwiseWinding(true), 
 	CurrentRendertargetSize(0,0), _device(device)
 {
 	#ifdef _DEBUG
@@ -177,7 +177,7 @@ COpenGLDriver::COpenGLDriver(const core::dimension2d<s32>& screenSize, bool full
 : CNullDriver(io, screenSize), COpenGLExtensionHandler(),
 	CurrentRenderMode(ERM_NONE), ResetRenderStates(true), Transformation3DChanged(true),
 	AntiAlias(antiAlias),
-	RenderTargetTexture(0), LastSetLight(-1),
+	LastSetLight(-1), RenderTargetTexture(0), ClockwiseWinding(true), 
 	CurrentRendertargetSize(0,0)
 {
 	#ifdef _DEBUG
@@ -213,7 +213,7 @@ COpenGLDriver::COpenGLDriver(const core::dimension2d<s32>& screenSize, bool full
 : CNullDriver(io, screenSize), COpenGLExtensionHandler(),
 	CurrentRenderMode(ERM_NONE), ResetRenderStates(true), Transformation3DChanged(true),
 	AntiAlias(antiAlias),
-	RenderTargetTexture(0), LastSetLight(-1),
+	LastSetLight(-1), RenderTargetTexture(0), ClockwiseWinding(true),
 	CurrentRendertargetSize(0,0)
 {
 	#ifdef _DEBUG
@@ -448,6 +448,25 @@ void COpenGLDriver::setTransform(E_TRANSFORMATION_STATE state, const core::matri
 		createGLMatrix(glmat, mat);
 		// flip z to compensate OpenGLs right-hand coordinate system
 		glmat[12] *= -1.0f;
+		// in render targets, flip the screen
+		if ( CurrentRendertargetSize.Width > 0 )
+		{
+			glmat[5] *= -1.0f;
+			// because we flipped the screen, triangles are the wrong way around
+			if (ClockwiseWinding)
+			{
+				glFrontFace(GL_CCW);
+				ClockwiseWinding = false;
+			}
+		}
+		else
+		{
+			if (!ClockwiseWinding)
+			{
+				glFrontFace(GL_CW);
+				ClockwiseWinding = true;
+			}
+		}
 		glMatrixMode(GL_PROJECTION);
 		glLoadMatrixf(glmat);
 		break;

source/Irrlicht/COpenGLDriver.h

@@ -329,6 +329,9 @@ namespace video
 		s32 LastSetLight;
 
 		core::dimension2d<s32> CurrentRendertargetSize;
+		//! bool to see if we are using clockwise or counter-clockwise winding,
+		//! render targets use opposite winding as their projection matrix is flipped.
+		bool ClockwiseWinding;
 
 		#ifdef _IRR_WINDOWS_API_
 			HDC HDc; // Private GDI Device Context