Access current/last render target via functions

To make it easier for functionality like screenshot capture and frame
rendering to use the correct render target this change introduces two
functions for use inside the renderer to borrow the currently presented
render target and a render target suitable for drawing.

Author: zao

engine/render/r_main.cpp

@@ -1372,8 +1372,7 @@ void r_renderer_c::EndFrame()
 	bool decideDraw = false;
 	bool elideDraw = false;
 	{
-		int drawRtt = 1 - presentRtt;
-		glBindFramebuffer(GL_FRAMEBUFFER, rttMain[drawRtt].framebuffer);
+		glBindFramebuffer(GL_FRAMEBUFFER, GetDrawRenderTarget().framebuffer);
 		glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
 		int l{};
 		for (l = 0; l < numLayer; l++) {
@@ -1402,7 +1401,7 @@ void r_renderer_c::EndFrame()
 			layer->Render();
 		}
 		if (!elideDraw) {
-			presentRtt = drawRtt;
+			presentRtt = 1 - presentRtt;
 			++drawnFrames;
 		}
 	}
@@ -1422,7 +1421,7 @@ void r_renderer_c::EndFrame()
 	delete[] layerSort;
 
 	{
-		auto rtt = rttMain[presentRtt];
+		auto& rtt = GetPresentRenderTarget();
 		glBindFramebuffer(GL_FRAMEBUFFER, 0);
 		glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
 		glClear(GL_DEPTH_BUFFER_BIT | GL_COLOR_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);
@@ -1833,7 +1832,7 @@ void r_renderer_c::DoScreenshot(image_c* i, const char* ext)
 	if (i->type != IMGTYPE_RGB) {
 		return;
 	}
-	auto& rt = rttMain[presentRtt];
+	auto& rt = GetPresentRenderTarget();
 	int const xs = rt.width;
 	int const ys = rt.height;
 
@@ -1848,7 +1847,7 @@ void r_renderer_c::DoScreenshot(image_c* i, const char* ext)
 	GLenum oglErr = glGetError();
 	GLenum implColorReadFormat{}, implColorReadType{};
 	glGetIntegerv(GL_FRAMEBUFFER_BINDING, &oldFb);
-	glBindFramebuffer(GL_FRAMEBUFFER, rttMain[presentRtt].framebuffer);
+	glBindFramebuffer(GL_FRAMEBUFFER, rt.framebuffer);
 	glPixelStorei(GL_PACK_ALIGNMENT, 1);
 	glReadPixels(0, 0, xs, ys, GL_RGBA, GL_UNSIGNED_BYTE, sbuf.data());
 	oglErr = glGetError();
@@ -1895,6 +1894,16 @@ void r_renderer_c::DoScreenshot(image_c* i, const char* ext)
 	}
 }
 
+r_renderer_c::RenderTarget& r_renderer_c::GetDrawRenderTarget()
+{
+	return rttMain[1 - presentRtt];
+}
+
+r_renderer_c::RenderTarget& r_renderer_c::GetPresentRenderTarget()
+{
+	return rttMain[presentRtt];
+}
+
 // ============================================
 // MurmurHash implementation from public domain
 // ============================================

engine/render/r_main.h

@@ -205,4 +205,7 @@ class r_renderer_c: public r_IRenderer, public conCmdHandler_c {
 	void	DoScreenshot(image_c* i, const char* ext);
 
 	void	C_Screenshot(IConsole* conHnd, args_c &args);
+
+	RenderTarget& GetDrawRenderTarget();
+	RenderTarget& GetPresentRenderTarget();
 };