godot/platform/windows/context_gl_windows.cpp

/**************************************************************************/
/*  context_gl_windows.cpp                                                */
/**************************************************************************/
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/*                             GODOT ENGINE                               */
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/* Copyright (c) 2014-present Godot Engine contributors (see AUTHORS.md). */
/* Copyright (c) 2007-2014 Juan Linietsky, Ariel Manzur.                  */
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#if defined(OPENGL_ENABLED) || defined(GLES_ENABLED)

// Author: Juan Linietsky <reduzio@gmail.com>, (C) 2008

#include "context_gl_windows.h"

#include <dwmapi.h>

#define WGL_CONTEXT_MAJOR_VERSION_ARB 0x2091
#define WGL_CONTEXT_MINOR_VERSION_ARB 0x2092
#define WGL_CONTEXT_FLAGS_ARB 0x2094
#define WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB 0x00000002
#define WGL_CONTEXT_PROFILE_MASK_ARB 0x9126
#define WGL_CONTEXT_CORE_PROFILE_BIT_ARB 0x00000001

#if defined(__GNUC__)
// Workaround GCC warning from -Wcast-function-type.
#define wglGetProcAddress (void *)wglGetProcAddress
#endif

typedef HGLRC(APIENTRY *PFNWGLCREATECONTEXTATTRIBSARBPROC)(HDC, HGLRC, const int *);

void ContextGL_Windows::release_current() {
	wglMakeCurrent(hDC, NULL);
}

void ContextGL_Windows::make_current() {
	wglMakeCurrent(hDC, hRC);
}

bool ContextGL_Windows::is_offscreen_available() const {
	return hRC_offscreen != NULL;
}

void ContextGL_Windows::make_offscreen_current() {
	ERR_FAIL_COND(!wglMakeCurrent(hDC, hRC_offscreen));
}

void ContextGL_Windows::release_offscreen_current() {
	ERR_FAIL_COND(!wglMakeCurrent(hDC, NULL));
}

HDC ContextGL_Windows::get_hdc() {
	return hDC;
}

HGLRC ContextGL_Windows::get_hglrc() {
	return hRC;
}

int ContextGL_Windows::get_window_width() {
	return OS::get_singleton()->get_video_mode().width;
}

int ContextGL_Windows::get_window_height() {
	return OS::get_singleton()->get_video_mode().height;
}

bool ContextGL_Windows::should_vsync_via_compositor() {
	if (OS::get_singleton()->is_window_fullscreen() || !OS::get_singleton()->is_vsync_via_compositor_enabled()) {
		return false;
	}

	// Note: All Windows versions supported by Godot have a compositor.
	// It can be disabled on earlier Windows versions.
	BOOL dwm_enabled;

	if (SUCCEEDED(DwmIsCompositionEnabled(&dwm_enabled))) {
		return dwm_enabled;
	}

	return false;
}

void ContextGL_Windows::swap_buffers() {
	SwapBuffers(hDC);

	if (use_vsync) {
		bool vsync_via_compositor_now = should_vsync_via_compositor();

		if (vsync_via_compositor_now && wglGetSwapIntervalEXT() == 0) {
			DwmFlush();
		}

		if (vsync_via_compositor_now != vsync_via_compositor) {
			// The previous frame had a different operating mode than this
			// frame. Set the 'vsync_via_compositor' member variable and the
			// OpenGL swap interval to their proper values.
			set_use_vsync(true);
		}
	}
}

void ContextGL_Windows::set_use_vsync(bool p_use) {
	vsync_via_compositor = p_use && should_vsync_via_compositor();

	if (wglSwapIntervalEXT) {
		int swap_interval = (p_use && !vsync_via_compositor) ? 1 : 0;
		wglSwapIntervalEXT(swap_interval);
	}

	use_vsync = p_use;
}

bool ContextGL_Windows::is_using_vsync() const {
	return use_vsync;
}

#define _WGL_CONTEXT_DEBUG_BIT_ARB 0x0001

Error ContextGL_Windows::initialize() {
	static PIXELFORMATDESCRIPTOR pfd = {
		sizeof(PIXELFORMATDESCRIPTOR), // Size Of This Pixel Format Descriptor
		1,
		PFD_DRAW_TO_WINDOW | // Format Must Support Window
				PFD_SUPPORT_OPENGL | // Format Must Support OpenGL
				PFD_DOUBLEBUFFER,
		(BYTE)PFD_TYPE_RGBA,
		(BYTE)(OS::get_singleton()->is_layered_allowed() ? 32 : 24),
		(BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, // Color Bits Ignored
		(BYTE)(OS::get_singleton()->is_layered_allowed() ? 8 : 0), // Alpha Buffer
		(BYTE)0, // Shift Bit Ignored
		(BYTE)0, // No Accumulation Buffer
		(BYTE)0, (BYTE)0, (BYTE)0, (BYTE)0, // Accumulation Bits Ignored
		(BYTE)24, // 24Bit Z-Buffer (Depth Buffer)
		(BYTE)0, // No Stencil Buffer
		(BYTE)0, // No Auxiliary Buffer
		(BYTE)PFD_MAIN_PLANE, // Main Drawing Layer
		(BYTE)0, // Reserved
		0, 0, 0 // Layer Masks Ignored
	};

	hDC = GetDC(hWnd);
	if (!hDC) {
		return ERR_CANT_CREATE; // Return FALSE
	}

	pixel_format = ChoosePixelFormat(hDC, &pfd);
	if (!pixel_format) // Did Windows Find A Matching Pixel Format?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	BOOL ret = SetPixelFormat(hDC, pixel_format, &pfd);
	if (!ret) // Are We Able To Set The Pixel Format?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	hRC = wglCreateContext(hDC);
	if (!hRC) // Are We Able To Get A Rendering Context?
	{
		return ERR_CANT_CREATE; // Return FALSE
	}

	wglMakeCurrent(hDC, hRC);

	if (opengl_3_context) {
		int attribs[] = {
			WGL_CONTEXT_MAJOR_VERSION_ARB, 3, //we want a 3.3 context
			WGL_CONTEXT_MINOR_VERSION_ARB, 3,
			//and it shall be forward compatible so that we can only use up to date functionality
			WGL_CONTEXT_PROFILE_MASK_ARB, WGL_CONTEXT_CORE_PROFILE_BIT_ARB,
			WGL_CONTEXT_FLAGS_ARB, WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB /*| _WGL_CONTEXT_DEBUG_BIT_ARB*/,
			0
		}; //zero indicates the end of the array

		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribsARB = NULL; //pointer to the method
		wglCreateContextAttribsARB = (PFNWGLCREATECONTEXTATTRIBSARBPROC)wglGetProcAddress("wglCreateContextAttribsARB");

		if (wglCreateContextAttribsARB == NULL) //OpenGL 3.0 is not supported
		{
			wglDeleteContext(hRC);
			return ERR_CANT_CREATE;
		}

		HGLRC new_hRC = wglCreateContextAttribsARB(hDC, 0, attribs);
		if (!new_hRC) {
			wglDeleteContext(hRC);
			return ERR_CANT_CREATE; // Return false
		}
		wglMakeCurrent(hDC, NULL);
		wglDeleteContext(hRC);
		hRC = new_hRC;

		if (!wglMakeCurrent(hDC, hRC)) // Try To Activate The Rendering Context
		{
			return ERR_CANT_CREATE; // Return FALSE
		}

		hRC_offscreen = wglCreateContextAttribsARB(hDC, 0, attribs);
	}

	wglSwapIntervalEXT = (PFNWGLSWAPINTERVALEXTPROC)wglGetProcAddress("wglSwapIntervalEXT");
	wglGetSwapIntervalEXT = (PFNWGLGETSWAPINTERVALEXTPROC)wglGetProcAddress("wglGetSwapIntervalEXT");
	//glWrapperInit(wrapper_get_proc_address);

	return OK;
}

ContextGL_Windows::ContextGL_Windows(HWND hwnd, bool p_opengl_3_context) {
	opengl_3_context = p_opengl_3_context;
	hWnd = hwnd;
	hRC_offscreen = NULL;
	use_vsync = false;
	vsync_via_compositor = false;
}

ContextGL_Windows::~ContextGL_Windows() {
}

#endif