From 01bda6348ed346223a296a77bd4292f13c571693 Mon Sep 17 00:00:00 2001
From: Magnus Norddahl <dpjudas@users.noreply.github.com>
Date: Mon, 18 Jun 2018 21:15:52 +0200
Subject: [PATCH] - change swrender mapping to use two buffers/textures and
 glTexSubImage2D for uploads

---
 src/gl/textures/gl_hwtexture.cpp |  8 ++++++--
 src/swrenderer/r_swscene.cpp     | 32 +++++++++++++++++---------------
 src/swrenderer/r_swscene.h       |  6 ++++--
 3 files changed, 27 insertions(+), 19 deletions(-)

diff --git a/src/gl/textures/gl_hwtexture.cpp b/src/gl/textures/gl_hwtexture.cpp
index 36feab0b7a..ef069114dc 100644
--- a/src/gl/textures/gl_hwtexture.cpp
+++ b/src/gl/textures/gl_hwtexture.cpp
@@ -192,7 +192,8 @@ unsigned int FHardwareTexture::CreateTexture(unsigned char * buffer, int w, int
 	}
 	*/
 	TranslatedTexture * glTex=GetTexID(translation);
-	if (glTex->glTexID==0) glGenTextures(1,&glTex->glTexID);
+	bool firstCall = glTex->glTexID == 0;
+	if (firstCall) glGenTextures(1,&glTex->glTexID);
 	if (texunit != 0) glActiveTexture(GL_TEXTURE0+texunit);
 	glBindTexture(GL_TEXTURE_2D, glTex->glTexID);
 	FGLDebug::LabelObject(GL_TEXTURE, glTex->glTexID, name);
@@ -256,7 +257,10 @@ unsigned int FHardwareTexture::CreateTexture(unsigned char * buffer, int w, int
 		sourcetype = GL_BGRA;
 	}
 	
-	glTexImage2D(GL_TEXTURE_2D, 0, texformat, rw, rh, 0, sourcetype, GL_UNSIGNED_BYTE, buffer);
+	if (!firstCall && glBufferID > 0)
+		glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, rw, rh, sourcetype, GL_UNSIGNED_BYTE, buffer);
+	else
+		glTexImage2D(GL_TEXTURE_2D, 0, texformat, rw, rh, 0, sourcetype, GL_UNSIGNED_BYTE, buffer);
 
 	if (deletebuffer && buffer) free(buffer);
 	else if (glBufferID)
diff --git a/src/swrenderer/r_swscene.cpp b/src/swrenderer/r_swscene.cpp
index 214fb2a0c9..8e25222669 100644
--- a/src/swrenderer/r_swscene.cpp
+++ b/src/swrenderer/r_swscene.cpp
@@ -86,38 +86,40 @@ public:
 
 SWSceneDrawer::SWSceneDrawer()
 {
-	PaletteTexture = new FSWPaletteTexture;
+	PaletteTexture.reset(new FSWPaletteTexture);
 }
 
 SWSceneDrawer::~SWSceneDrawer()
 {
-	if (PaletteTexture != nullptr) delete PaletteTexture;
-	if (FBTexture != nullptr) delete FBTexture;
 }
 
 sector_t *SWSceneDrawer::RenderView(player_t *player)
 {
+	// Avoid using the pixel buffer from the last frame
+	FBTextureIndex = (FBTextureIndex + 1) % 2;
+	auto &fbtex = FBTexture[FBTextureIndex];
+
 	DCanvas buffer(screen->GetWidth(), screen->GetHeight(), V_IsTrueColor());
-	if (FBTexture == nullptr || FBTexture->SystemTexture[0] == nullptr || 
-		FBTexture->GetWidth() != screen->GetWidth() || 
-		FBTexture->GetHeight() != screen->GetHeight() || 
-		(V_IsTrueColor() ? 1:0) != FBTexture->WidthBits)
+	if (fbtex == nullptr || fbtex->SystemTexture[0] == nullptr || 
+		fbtex->GetWidth() != screen->GetWidth() || 
+		fbtex->GetHeight() != screen->GetHeight() || 
+		(V_IsTrueColor() ? 1:0) != fbtex->WidthBits)
 	{
 		// This manually constructs its own material here.
-		if (FBTexture != nullptr) delete FBTexture;
-		FBTexture = new FSWSceneTexture(screen->GetWidth(), screen->GetHeight(), V_IsTrueColor());
-		FBTexture->SystemTexture[0]->AllocateBuffer(screen->GetWidth(), screen->GetHeight(), V_IsTrueColor() ? 4 : 1);
-		auto mat = FMaterial::ValidateTexture(FBTexture, false);
-		mat->AddTextureLayer(PaletteTexture);
+		fbtex.reset();
+		fbtex.reset(new FSWSceneTexture(screen->GetWidth(), screen->GetHeight(), V_IsTrueColor()));
+		fbtex->SystemTexture[0]->AllocateBuffer(screen->GetWidth(), screen->GetHeight(), V_IsTrueColor() ? 4 : 1);
+		auto mat = FMaterial::ValidateTexture(fbtex.get(), false);
+		mat->AddTextureLayer(PaletteTexture.get());
 	}
-	auto buf = FBTexture->SystemTexture[0]->MapBuffer();
+	auto buf = fbtex->SystemTexture[0]->MapBuffer();
 	if (!buf) I_FatalError("Unable to map buffer for software rendering");
 	buffer.SetBuffer(screen->GetWidth(), screen->GetHeight(), screen->GetWidth(), buf);
 	SWRenderer->RenderView(player, &buffer);
-	FBTexture->SystemTexture[0]->CreateTexture(nullptr, screen->GetWidth(), screen->GetHeight(), 0, false, 0, "swbuffer");
+	fbtex->SystemTexture[0]->CreateTexture(nullptr, screen->GetWidth(), screen->GetHeight(), 0, false, 0, "swbuffer");
 
 	auto map = swrenderer::CameraLight::Instance()->ShaderColormap();
-	screen->DrawTexture(FBTexture, 0, 0, DTA_SpecialColormap, map, TAG_DONE);
+	screen->DrawTexture(fbtex.get(), 0, 0, DTA_SpecialColormap, map, TAG_DONE);
 	SWRenderer->DrawRemainingPlayerSprites();
 	return r_viewpoint.sector;
 }
diff --git a/src/swrenderer/r_swscene.h b/src/swrenderer/r_swscene.h
index ef52c20c65..9c6921ee41 100644
--- a/src/swrenderer/r_swscene.h
+++ b/src/swrenderer/r_swscene.h
@@ -6,13 +6,15 @@
 #include "hwrenderer/scene/hw_clipper.h"
 #include "r_utility.h"
 #include "c_cvars.h"
+#include <memory>
 
 class FSWSceneTexture;
 
 class SWSceneDrawer
 {
-	FTexture *PaletteTexture = nullptr;
-	FSWSceneTexture *FBTexture = nullptr;
+	std::unique_ptr<FTexture> PaletteTexture;
+	std::unique_ptr<FSWSceneTexture> FBTexture[2];
+	int FBTextureIndex = 0;
 	bool FBIsTruecolor = false;
 
 public: