From 5e5a624681a268e759df53edc15a73f587fda6df Mon Sep 17 00:00:00 2001
From: aap <aap@papnet.eu>
Date: Sun, 25 Oct 2020 11:10:14 +0100
Subject: [PATCH] subraster rendering on gl

---
 src/gl/gl3device.cpp | 36 ++++++++++++++++++++++++++++++------
 src/rwbase.h         |  2 +-
 2 files changed, 31 insertions(+), 7 deletions(-)

diff --git a/src/gl/gl3device.cpp b/src/gl/gl3device.cpp
index b07e823..877141c 100644
--- a/src/gl/gl3device.cpp
+++ b/src/gl/gl3device.cpp
@@ -52,6 +52,7 @@ struct GlGlobals
 	GLFWwindow **pWindow;
 #endif
 	int presentWidth, presentHeight;
+	int presentOffX, presentOffY;
 
 	// for opening the window
 	int winWidth, winHeight;
@@ -1036,8 +1037,8 @@ flushCache(void)
 static void
 setFrameBuffer(Camera *cam)
 {
-	Raster *fbuf = cam->frameBuffer;
-	Raster *zbuf = cam->zBuffer;
+	Raster *fbuf = cam->frameBuffer->parent;
+	Raster *zbuf = cam->zBuffer->parent;
 	assert(fbuf);
 
 	Gl3Raster *natfb = PLUGINOFFSET(Gl3Raster, fbuf, nativeRasterOffset);
@@ -1151,24 +1152,45 @@ beginUpdate(Camera *cam)
 	setFrameBuffer(cam);
 
 	int w, h;
-	if(cam->frameBuffer->type == Raster::CAMERA){
+	int x, y;
+	Raster *fb = cam->frameBuffer->parent;
+	if(fb->type == Raster::CAMERA){
 #ifdef LIBRW_SDL2
 		SDL_GetWindowSize(glGlobals.window, &w, &h);
 #else
 		glfwGetWindowSize(glGlobals.window, &w, &h);
 #endif
 	}else{
+		w = fb->width;
+		h = fb->height;
+	}
+	x = 0;
+	y = 0;
+
+	// Got a subraster
+	if(cam->frameBuffer != fb){
+		x = cam->frameBuffer->offsetX;
+		// GL y offset is from bottom
+		y = h - cam->frameBuffer->height - cam->frameBuffer->offsetY;
 		w = cam->frameBuffer->width;
 		h = cam->frameBuffer->height;
 	}
 
-	if(w != glGlobals.presentWidth || h != glGlobals.presentHeight){
-		glViewport(0, 0, w, h);
+	if(w != glGlobals.presentWidth || h != glGlobals.presentHeight ||
+	   x != glGlobals.presentOffX || y != glGlobals.presentOffY){
+		glViewport(x, y, w, h);
 		glGlobals.presentWidth = w;
 		glGlobals.presentHeight = h;
+		glGlobals.presentOffX = x;
+		glGlobals.presentOffY = y;
 	}
 }
 
+static void
+endUpdate(Camera *cam)
+{
+}
+
 static void
 clearCamera(Camera *cam, RGBA *col, uint32 mode)
 {
@@ -1442,6 +1464,8 @@ printf("version %s\n", glGetString(GL_VERSION));
 	*glGlobals.pWindow = win;
 	glGlobals.presentWidth = 0;
 	glGlobals.presentHeight = 0;
+	glGlobals.presentOffX = 0;
+	glGlobals.presentOffY = 0;
 	return 1;
 }
 
@@ -1656,7 +1680,7 @@ deviceSystemGLFW(DeviceReq req, void *arg, int32 n)
 Device renderdevice = {
 	-1.0f, 1.0f,
 	gl3::beginUpdate,
-	null::endUpdate,
+	gl3::endUpdate,
 	gl3::clearCamera,
 	gl3::showRaster,
 	gl3::rasterRenderFast,
diff --git a/src/rwbase.h b/src/rwbase.h
index 6b40302..573269c 100644
--- a/src/rwbase.h
+++ b/src/rwbase.h
@@ -387,8 +387,8 @@ struct Line
 
 struct Rect
 {
-	int32 h, w;
 	int32 x, y;
+	int32 w, h;
 };
 
 struct Sphere