Add a debug mode window to show game framebuffer

I was trying to debug issues with rendering for dirty rectangles, so I added a window to show the contents of the framebuffer that backs the dirty rect system. The color output is wrong because OpenGL's pixels are BGR and I'm just rendering it to the HWND as RGB, but that doesn't really matter.
nsgomez · Oct 19, 2024 · 8f5a632 · 8f5a632
1 parent 8c32ae4
commit 8f5a632
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Showing 4 changed files with 126 additions and 0 deletions.
diff --git a/scgl/cGDriver.h b/scgl/cGDriver.h
@@ -98,6 +98,12 @@ namespace nSCGL
 		void* deviceContext;
 		void* glContext;
 
+#ifndef NDEBUG
+		void* secondaryWindow;
+		void* secondaryDeviceContext;
+		void* pixels;
+#endif
+
 	private:
 		void SetLastError(DriverError err);
 		void DestroyOpenGLContext();

diff --git a/scgl/cGDriver_Init.cpp b/scgl/cGDriver_Init.cpp
@@ -5,6 +5,24 @@
 namespace nSCGL
 {
 	bool cGDriver::Init(void) {
+#ifndef NDEBUG
+		WNDCLASS wcDebug{};
+		wcDebug.style = CS_OWNDC;
+		wcDebug.lpfnWndProc = DefWindowProcA;
+		wcDebug.hInstance = GetModuleHandle(nullptr);
+		wcDebug.lpszClassName = "GDriverClass--OpenGLDebug";
+
+		UnregisterClass(wcDebug.lpszClassName, nullptr);
+
+		if (!RegisterClass(&wcDebug)) {
+			DWORD err = GetLastError();
+			if (err != ERROR_CLASS_ALREADY_EXISTS) {
+				MessageBoxA(NULL, "Failed to set up an OpenGL debug window class", "SCGL failed to start", MB_ICONERROR);
+				return false;
+			}
+		}
+#endif
+
 		// Create an invisible default window to set up an initial OpenGL context
 		WNDCLASS wc{};
 		wc.style = CS_OWNDC;

diff --git a/scgl/cGDriver_Viewport.cpp b/scgl/cGDriver_Viewport.cpp
@@ -207,6 +207,53 @@ namespace nSCGL
 				return;
 			}
 
+#ifndef NDEBUG
+			{
+				HWND secondaryHwnd = CreateWindowExA(
+					dwExtStyle,
+					"GDriverClass--OpenGLDebug",
+					"GDriverWindow--OpenGLDebug",
+					(dwStyle) & ~(WS_EX_APPWINDOW | WS_POPUP),
+					wndRect.left,
+					wndRect.top,
+					wndRect.right - wndRect.left,
+					wndRect.bottom - wndRect.top,
+					nullptr,
+					nullptr,
+					GetModuleHandle(nullptr),
+					nullptr);
+
+				if (secondaryHwnd == nullptr) {
+					DWORD error = GetLastError();
+					MessageBoxA(NULL, "Failed to create window.", "SCGL video mode error", MB_ICONWARNING);
+					return;
+				}
+
+				HDC secondaryDC = GetDC(secondaryHwnd);
+				secondaryWindow = secondaryHwnd;
+				secondaryDeviceContext = secondaryDC;
+
+				pfd.nSize = sizeof(PIXELFORMATDESCRIPTOR);
+				pfd.nVersion = 1;
+				pfd.dwFlags = PFD_DRAW_TO_WINDOW;
+				pfd.iPixelType = PFD_TYPE_RGBA;
+				pfd.cAlphaBits = (newMode.depth == 32) ? 8 : 1;
+				pfd.cColorBits = (newMode.depth == 32) ? 24 : 15;
+				pfd.cDepthBits = (newMode.depth == 32) ? 24 : 16;
+				pfd.cStencilBits = 8;
+				pfd.iLayerType = PFD_MAIN_PLANE;
+
+				pixelFormat = ChoosePixelFormat(secondaryDC, &pfd);
+
+				if (!SetPixelFormat(secondaryDC, pixelFormat, &pfd)) {
+					MessageBoxA(NULL, "Failed to set video mode on debug window.", "SCGL video mode error", MB_ICONWARNING);
+				}
+
+				ShowWindow(secondaryHwnd, SW_SHOWNORMAL);
+				pixels = new char[3 * newMode.width * newMode.height];
+			}
+#endif
+
 			wglMakeCurrent(hdc, static_cast<HGLRC>(glContext));
 
 			if (supportedExtensions.swapControl) {

diff --git a/scgl/ext/cGDriver_BufferRegions.cpp b/scgl/ext/cGDriver_BufferRegions.cpp
@@ -101,6 +101,61 @@ namespace nSCGL
 		glBlitFramebuffer(srcX0, srcY0, srcX1, srcY1, dstX0, dstY0, dstX1, dstY1, framebufferMasks[bufferRegionIndex], GL_NEAREST);
 		glBindFramebuffer(GL_DRAW_FRAMEBUFFER, 0);
 
+#ifndef NDEBUG
+		if (framebufferMasks[bufferRegionIndex] == GL_COLOR_BUFFER_BIT)
+		{
+			glFinish();
+
+			memset(pixels, 127, width * height * 3);
+			glReadPixels(srcX0, srcY0, width, height, GL_RGB, GL_UNSIGNED_BYTE, pixels);
+
+			InvalidateRect((HWND)secondaryWindow, nullptr, TRUE);
+
+			PAINTSTRUCT ps;
+			DWORD dwError;
+			HDC hdc = BeginPaint((HWND)secondaryWindow, &ps);
+
+			dwError = GetLastError();
+
+			BITMAPINFO bm;
+			bm.bmiHeader.biSize = sizeof(BITMAPINFOHEADER);
+			bm.bmiHeader.biWidth = width;
+			bm.bmiHeader.biHeight = height;
+			bm.bmiHeader.biPlanes = 1;
+			bm.bmiHeader.biBitCount = 24;
+			bm.bmiHeader.biCompression = BI_RGB;
+			bm.bmiHeader.biSizeImage = 0;
+			bm.bmiHeader.biXPelsPerMeter = 2835;
+			bm.bmiHeader.biYPelsPerMeter = 2835;
+			bm.bmiHeader.biClrUsed = 0;
+			bm.bmiHeader.biClrImportant = 0;
+			bm.bmiColors->rgbBlue = 255;
+			bm.bmiColors->rgbGreen = 255;
+			bm.bmiColors->rgbRed = 255;
+			bm.bmiColors->rgbReserved = 0;
+
+			dwError = ::SetDIBitsToDevice(
+				hdc,
+				dstX0,
+				windowHeight - dstY1,
+				width,
+				height,
+				0,
+				0,
+				0,
+				height,
+				pixels,
+				&bm,
+				DIB_RGB_COLORS);
+
+			dwError = GetLastError();
+
+			EndPaint((HWND)secondaryWindow, &ps);
+
+			dwError = GetLastError();
+		}
+#endif
+
 		return true;
 	}