OGL: Use floating points for viewport parameters.

As told by neobain, ARB_viewport_array introduced float viewports.
They must be supported on OGL4.1+, but it's usually also implemented on 3.3 GPUs.

2 files changed, 17 insertions, 7 deletions

diff --git a/Source/Core/VideoBackends/OGL/Src/Render.cpp b/Source/Core/VideoBackends/OGL/Src/Render.cpp
index 4dca112031..e507fc45cd 100644
--- a/Source/Core/VideoBackends/OGL/Src/Render.cpp
+++ b/Source/Core/VideoBackends/OGL/Src/Render.cpp
@@ -386,6 +386,7 @@ Renderer::Renderer()
 	g_ogl_config.bSupportCoverageMSAA = false; // XXX: GLES3 spec has MSAA
 	g_ogl_config.bSupportSampleShading = false; 
 	g_ogl_config.bSupportOGL31 = false; 
+	g_ogl_config.bSupportViewportFloat = false;
 	if (DriverDetails::HasBug(DriverDetails::BUG_ISTEGRA) || DriverDetails::HasBug(DriverDetails::BUG_ISPOWERVR))
 		g_ogl_config.eSupportedGLSLVersion = GLSLES2;
 	else
@@ -496,6 +497,7 @@ Renderer::Renderer()
 	g_ogl_config.bSupportCoverageMSAA = GLEW_NV_framebuffer_multisample_coverage;
 	g_ogl_config.bSupportSampleShading = GLEW_ARB_sample_shading;
 	g_ogl_config.bSupportOGL31 = GLEW_VERSION_3_1;
+	g_ogl_config.bSupportViewportFloat = GLEW_ARB_viewport_array;
 
 	if(strstr(g_ogl_config.glsl_version, "1.00") || strstr(g_ogl_config.glsl_version, "1.10") || strstr(g_ogl_config.glsl_version, "1.20"))
 	{
@@ -1105,12 +1107,12 @@ void Renderer::UpdateViewport(Matrix44& vpCorrection)
 	int scissorYOff = bpmem.scissorOffset.y * 2;
 
 	// TODO: ceil, floor or just cast to int?
-	int X = EFBToScaledX((int)ceil(xfregs.viewport.xOrig - xfregs.viewport.wd - (float)scissorXOff));
-	int Y = EFBToScaledY((int)ceil((float)EFB_HEIGHT - xfregs.viewport.yOrig + xfregs.viewport.ht + (float)scissorYOff));
-	int Width = EFBToScaledX((int)ceil(2.0f * xfregs.viewport.wd));
-	int Height = EFBToScaledY((int)ceil(-2.0f * xfregs.viewport.ht));
-	double GLNear = (xfregs.viewport.farZ - xfregs.viewport.zRange) / 16777216.0f;
-	double GLFar = xfregs.viewport.farZ / 16777216.0f;
+	float X = EFBToScaledXf(xfregs.viewport.xOrig - xfregs.viewport.wd - (float)scissorXOff);
+	float Y = EFBToScaledYf((float)EFB_HEIGHT - xfregs.viewport.yOrig + xfregs.viewport.ht + (float)scissorYOff);
+	float Width = EFBToScaledXf(2.0f * xfregs.viewport.wd);
+	float Height = EFBToScaledYf(-2.0f * xfregs.viewport.ht);
+	float GLNear = (xfregs.viewport.farZ - xfregs.viewport.zRange) / 16777216.0f;
+	float GLFar = xfregs.viewport.farZ / 16777216.0f;
 	if (Width < 0)
 	{
 		X += Width;
@@ -1126,7 +1128,14 @@ void Renderer::UpdateViewport(Matrix44& vpCorrection)
 	Matrix44::LoadIdentity(vpCorrection);
 
 	// Update the view port
-	glViewport(X, Y, Width, Height);
+	if(g_ogl_config.bSupportViewportFloat)
+	{
+		glViewportIndexedf(0, X, Y, Width, Height);
+	}
+	else
+	{
+		glViewport(round(X), round(Y), round(Width), round(Height));
+	}
 	glDepthRangef(GLNear, GLFar);
 }
 
diff --git a/Source/Core/VideoBackends/OGL/Src/Render.h b/Source/Core/VideoBackends/OGL/Src/Render.h
index 8c6a8ca8f8..efafb8708d 100644
--- a/Source/Core/VideoBackends/OGL/Src/Render.h
+++ b/Source/Core/VideoBackends/OGL/Src/Render.h
@@ -27,6 +27,7 @@ extern struct VideoConfig {
 	bool bSupportSampleShading;
 	GLSL_VERSION eSupportedGLSLVersion;
 	bool bSupportOGL31;
+	bool bSupportViewportFloat;
 	
 	const char *gl_vendor;
 	const char *gl_renderer;