obs-studio/plugins/win-capture/graphics-hook/gl-capture.c

#define _CRT_SECURE_NO_WARNINGS
#pragma warning(disable : 4214) /* nonstandard extension, non-int bitfield */
#pragma warning(disable : 4054) /* function pointer to data pointer */
#include <windows.h>

#define COBJMACROS
#include <dxgi.h>
#include <d3d11.h>

#include "gl-decs.h"
#include "graphics-hook.h"
#include "../funchook.h"

#define DUMMY_WINDOW_CLASS_NAME L"graphics_hook_gl_dummy_window"

static const GUID GUID_IDXGIFactory1 =
{0x770aae78, 0xf26f, 0x4dba, {0xa8, 0x29, 0x25, 0x3c, 0x83, 0xd1, 0xb3, 0x87}};
static const GUID GUID_IDXGIResource =
{0x035f3ab4, 0x482e, 0x4e50, {0xb4, 0x1f, 0x8a, 0x7f, 0x8b, 0xd8, 0x96, 0x0b}};

static struct func_hook swap_buffers;
static struct func_hook wgl_swap_layer_buffers;
static struct func_hook wgl_swap_buffers;
static struct func_hook wgl_delete_context;

struct gl_data {
	HDC                            hdc;
	uint32_t                       base_cx;
	uint32_t                       base_cy;
	uint32_t                       cx;
	uint32_t                       cy;
	DXGI_FORMAT                    format;
	GLuint                         fbo;
	bool                           using_shtex : 1;
	bool                           using_scale : 1;

	union {
		/* shared texture */
		struct {
			struct shtex_data      *shtex_info;
			ID3D11Device           *d3d11_device;
			ID3D11DeviceContext    *d3d11_context;
			ID3D11Texture2D        *d3d11_tex;
			IDXGISwapChain         *dxgi_swap;
			HANDLE                 gl_device;
			HANDLE                 gl_dxobj;
			HANDLE                 handle;
			HWND                   hwnd;
			GLuint                 texture;
		};
		/* shared memory */
		struct {
			struct shmem_data      *shmem_info;
			int                    cur_tex;
			int                    copy_wait;
			GLuint                 pbos[NUM_BUFFERS];
			GLuint                 textures[NUM_BUFFERS];
			bool                   texture_ready[NUM_BUFFERS];
			bool                   texture_mapped[NUM_BUFFERS];
		};
	};
};

static HMODULE gl = NULL;
static bool nv_capture_available = false;
static struct gl_data data = {0};

static inline bool gl_error(const char *func, const char *str)
{
	GLenum error = glGetError();
	if (error != 0) {
		hlog("%s: %s: %lu", func, str, error);
		return true;
	}

	return false;
}

static void gl_free(void)
{
	capture_free();

	if (data.using_shtex) {
		if (data.gl_dxobj)
			jimglDXUnregisterObjectNV(data.gl_device,
					data.gl_dxobj);
		if (data.gl_device)
			jimglDXCloseDeviceNV(data.gl_device);
		if (data.texture)
			glDeleteTextures(1, &data.texture);
		if (data.d3d11_tex)
			ID3D11Resource_Release(data.d3d11_tex);
		if (data.d3d11_context)
			ID3D11DeviceContext_Release(data.d3d11_context);
		if (data.d3d11_device)
			ID3D11Device_Release(data.d3d11_device);
		if (data.dxgi_swap)
			IDXGISwapChain_Release(data.dxgi_swap);
		if (data.hwnd)
			DestroyWindow(data.hwnd);
	} else {
		for (size_t i = 0; i < NUM_BUFFERS; i++) {
			if (data.pbos[i]) {
				if (data.texture_mapped[i]) {
					glBindBuffer(GL_PIXEL_PACK_BUFFER,
							data.pbos[i]);
					glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
					glBindBuffer(GL_PIXEL_PACK_BUFFER, 0);
				}

				glDeleteBuffers(1, &data.pbos[i]);
			}

			if (data.textures[i])
				glDeleteTextures(1, &data.textures[i]);
		}
	}

	if (data.fbo)
		glDeleteFramebuffers(1, &data.fbo);

	gl_error("gl_free", "GL error occurred on free");

	memset(&data, 0, sizeof(data));

	hlog("------------------ gl capture freed ------------------");
}

static inline void *base_get_proc(const char *name)
{
	return (void*)GetProcAddress(gl, name);
}

static inline void *wgl_get_proc(const char *name)
{
	return (void*)jimglGetProcAddress(name);
}

static inline void *get_proc(const char *name)
{
	void *func = wgl_get_proc(name);
	if (!func)
		func = base_get_proc(name);

	return func;
}

static void init_nv_functions(void)
{
	jimglDXSetResourceShareHandleNV =
		get_proc("wglDXSetResourceShareHandleNV");
	jimglDXOpenDeviceNV = get_proc("wglDXOpenDeviceNV");
	jimglDXCloseDeviceNV = get_proc("wglDXCloseDeviceNV");
	jimglDXRegisterObjectNV = get_proc("wglDXRegisterObjectNV");
	jimglDXUnregisterObjectNV = get_proc("wglDXUnregisterObjectNV");
	jimglDXObjectAccessNV = get_proc("wglDXObjectAccessNV");
	jimglDXLockObjectsNV = get_proc("wglDXLockObjectsNV");
	jimglDXUnlockObjectsNV = get_proc("wglDXUnlockObjectsNV");

	nv_capture_available =
		!!jimglDXSetResourceShareHandleNV &&
		!!jimglDXOpenDeviceNV &&
		!!jimglDXCloseDeviceNV &&
		!!jimglDXRegisterObjectNV &&
		!!jimglDXUnregisterObjectNV &&
		!!jimglDXObjectAccessNV &&
		!!jimglDXLockObjectsNV &&
		!!jimglDXUnlockObjectsNV;

	if (nv_capture_available)
		hlog("Shared-texture OpenGL capture available");
}

#define GET_PROC(cur_func, ptr, func) \
	do { \
		ptr = get_proc(#func); \
		if (!ptr) { \
			hlog("%s: failed to get function '%s'", #cur_func, \
					#func); \
			success = false; \
		} \
	} while (false)

static bool init_gl_functions(void)
{
	bool success = true;

	jimglGetProcAddress = base_get_proc("wglGetProcAddress");
	if (!jimglGetProcAddress) {
		hlog("init_gl_functions: failed to get wglGetProcAddress");
		return false;
	}

	GET_PROC(init_gl_functions, jimglMakeCurrent, wglMakeCurrent);
	GET_PROC(init_gl_functions, jimglGetCurrentDC, wglGetCurrentDC);
	GET_PROC(init_gl_functions, jimglGetCurrentContext,
			wglGetCurrentContext);
	GET_PROC(init_gl_functions, glTexImage2D, glTexImage2D);
	GET_PROC(init_gl_functions, glReadBuffer, glReadBuffer);
	GET_PROC(init_gl_functions, glGetTexImage, glGetTexImage);
	GET_PROC(init_gl_functions, glDrawBuffer, glDrawBuffer);
	GET_PROC(init_gl_functions, glGetError, glGetError);
	GET_PROC(init_gl_functions, glBufferData, glBufferData);
	GET_PROC(init_gl_functions, glDeleteBuffers, glDeleteBuffers);
	GET_PROC(init_gl_functions, glDeleteTextures, glDeleteTextures);
	GET_PROC(init_gl_functions, glGenBuffers, glGenBuffers);
	GET_PROC(init_gl_functions, glGenTextures, glGenTextures);
	GET_PROC(init_gl_functions, glMapBuffer, glMapBuffer);
	GET_PROC(init_gl_functions, glUnmapBuffer, glUnmapBuffer);
	GET_PROC(init_gl_functions, glBindBuffer, glBindBuffer);
	GET_PROC(init_gl_functions, glGetIntegerv, glGetIntegerv);
	GET_PROC(init_gl_functions, glBindTexture, glBindTexture);
	GET_PROC(init_gl_functions, glGenFramebuffers, glGenFramebuffers);
	GET_PROC(init_gl_functions, glDeleteFramebuffers, glDeleteFramebuffers);
	GET_PROC(init_gl_functions, glBindFramebuffer, glBindFramebuffer);
	GET_PROC(init_gl_functions, glBlitFramebuffer, glBlitFramebuffer);
	GET_PROC(init_gl_functions, glFramebufferTexture2D,
			glFramebufferTexture2D);

	init_nv_functions();
	return success;
}

static void get_window_size(HDC hdc, uint32_t *cx, uint32_t *cy)
{
	HWND hwnd = WindowFromDC(hdc);
        RECT rc = {0};

        GetClientRect(hwnd, &rc);
	*cx = rc.right;
	*cy = rc.bottom;
}

static inline bool gl_shtex_init_window(void)
{
	data.hwnd = CreateWindowExW(0, DUMMY_WINDOW_CLASS_NAME,
			L"Dummy GL window, ignore",
			WS_POPUP | WS_CLIPCHILDREN | WS_CLIPSIBLINGS,
			0, 0, 2, 2, NULL, NULL, GetModuleHandle(NULL), NULL);
	if (!data.hwnd) {
		hlog("gl_shtex_init_window: failed to create window: %d",
				GetLastError());
		return false;
	}

	return true;
}

typedef HRESULT (WINAPI *create_dxgi_factory1_t)(REFIID, void **);

const static D3D_FEATURE_LEVEL feature_levels[] =
{
	D3D_FEATURE_LEVEL_11_0,
	D3D_FEATURE_LEVEL_10_1,
	D3D_FEATURE_LEVEL_10_0,
	D3D_FEATURE_LEVEL_9_3,
};

static inline bool gl_shtex_init_d3d11(void)
{
	D3D_FEATURE_LEVEL level_used;
	IDXGIFactory1 *factory;
	IDXGIAdapter *adapter;
	HRESULT hr;

	HMODULE d3d11 = load_system_library("d3d11.dll");
	if (!d3d11) {
		hlog("gl_shtex_init_d3d11: failed to load D3D11.dll: %d",
				GetLastError());
		return false;
	}

	HMODULE dxgi = load_system_library("dxgi.dll");
	if (!dxgi) {
		hlog("gl_shtex_init_d3d11: failed to load DXGI.dll: %d",
				GetLastError());
		return false;
	}

	DXGI_SWAP_CHAIN_DESC desc      = {0};
	desc.BufferCount               = 2;
	desc.BufferDesc.Format         = DXGI_FORMAT_B8G8R8A8_UNORM;
	desc.BufferDesc.Width          = 2;
	desc.BufferDesc.Height         = 2;
	desc.BufferUsage               = DXGI_USAGE_RENDER_TARGET_OUTPUT;
	desc.SampleDesc.Count          = 1;
	desc.Windowed                  = true;
	desc.OutputWindow              = data.hwnd;

	create_dxgi_factory1_t create_factory = (void*)GetProcAddress(dxgi,
			"CreateDXGIFactory1");
	if (!create_factory) {
		hlog("gl_shtex_init_d3d11: failed to load CreateDXGIFactory1 "
		     "procedure: %d", GetLastError());
		return false;
	}

	PFN_D3D11_CREATE_DEVICE_AND_SWAP_CHAIN create = (void*)GetProcAddress(
			d3d11, "D3D11CreateDeviceAndSwapChain");
	if (!create) {
		hlog("gl_shtex_init_d3d11: failed to load "
		     "D3D11CreateDeviceAndSwapChain procedure: %d",
		     GetLastError());
		return false;
	}

	hr = create_factory(&GUID_IDXGIFactory1, (void**)&factory);
	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11: failed to create factory", hr);
		return false;
	}

	hr = IDXGIFactory1_EnumAdapters1(factory, 0, (IDXGIAdapter1**)&adapter);
	IDXGIFactory1_Release(factory);

	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11: failed to create adapter", hr);
		return false;
	}

	hr = create(adapter, D3D_DRIVER_TYPE_UNKNOWN, NULL, 0, feature_levels,
			sizeof(feature_levels) / sizeof(D3D_FEATURE_LEVEL),
			D3D11_SDK_VERSION, &desc, &data.dxgi_swap,
			&data.d3d11_device, &level_used, &data.d3d11_context);
	IDXGIAdapter_Release(adapter);

	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11: failed to create device", hr);
		return false;
	}

	return true;
}

static inline bool gl_shtex_init_d3d11_tex(void)
{
	IDXGIResource *dxgi_res;
	HRESULT hr;

	D3D11_TEXTURE2D_DESC desc      = {0};
	desc.Width                     = data.cx;
	desc.Height                    = data.cy;
	desc.MipLevels                 = 1;
	desc.ArraySize                 = 1;
	desc.Format                    = DXGI_FORMAT_B8G8R8A8_UNORM;
	desc.SampleDesc.Count          = 1;
	desc.Usage                     = D3D11_USAGE_DEFAULT;
	desc.MiscFlags                 = D3D11_RESOURCE_MISC_SHARED;
	desc.BindFlags                 = D3D11_BIND_RENDER_TARGET |
	                                 D3D11_BIND_SHADER_RESOURCE;

	hr = ID3D11Device_CreateTexture2D(data.d3d11_device, &desc, NULL,
			&data.d3d11_tex);
	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11_tex: failed to create texture",
				hr);
		return false;
	}

	hr = ID3D11Device_QueryInterface(data.d3d11_tex,
			&GUID_IDXGIResource, (void**)&dxgi_res);
	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11_tex: failed to get IDXGIResource",
				hr);
		return false;
	}

	hr = IDXGIResource_GetSharedHandle(dxgi_res, &data.handle);
	IDXGIResource_Release(dxgi_res);

	if (FAILED(hr)) {
		hlog_hr("gl_shtex_init_d3d11_tex: failed to get shared handle",
				hr);
		return false;
	}

	return true;
}

static inline bool gl_shtex_init_gl_tex(void)
{
	data.gl_device = jimglDXOpenDeviceNV(data.d3d11_device);
	if (!data.gl_device) {
		hlog("gl_shtex_init_gl_tex: failed to open device");
		return false;
	}

	glGenTextures(1, &data.texture);
	if (gl_error("gl_shtex_init_gl_tex", "failed to generate texture")) {
		return false;
	}

	data.gl_dxobj = jimglDXRegisterObjectNV(data.gl_device, data.d3d11_tex,
			data.texture, GL_TEXTURE_2D,
			WGL_ACCESS_WRITE_DISCARD_NV);
	if (!data.gl_dxobj) {
		hlog("gl_shtex_init_gl_tex: failed to register object");
		return false;
	}

	return true;
}

static inline bool gl_init_fbo(void)
{
	glGenFramebuffers(1, &data.fbo);
	return !gl_error("gl_init_fbo", "failed to initialize FBO");
}

static bool gl_shtex_init(HWND window)
{
	if (!gl_shtex_init_window()) {
		return false;
	}
	if (!gl_shtex_init_d3d11()) {
		return false;
	}
	if (!gl_shtex_init_d3d11_tex()) {
		return false;
	}
	if (!gl_shtex_init_gl_tex()) {
		return false;
	}
	if (!gl_init_fbo()) {
		return false;
	}
	if (!capture_init_shtex(&data.shtex_info, window,
				data.base_cx, data.base_cy, data.cx, data.cy,
				data.format, true, (uint32_t)data.handle)) {
		return false;
	}

	hlog("gl shared texture capture successful");
	return true;
}

static inline bool gl_shmem_init_data(size_t idx, size_t size)
{
	glBindBuffer(GL_PIXEL_PACK_BUFFER, data.pbos[idx]);
	if (gl_error("gl_shmem_init_data", "failed to bind pbo")) {
		return false;
	}

	glBufferData(GL_PIXEL_PACK_BUFFER, size, 0, GL_STREAM_READ);
	if (gl_error("gl_shmem_init_data", "failed to set pbo data")) {
		return false;
	}

	glBindTexture(GL_TEXTURE_2D, data.textures[idx]);
	if (gl_error("gl_shmem_init_data", "failed to set bind texture")) {
		return false;
	}

	glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, data.cx, data.cy,
			0, GL_BGRA, GL_UNSIGNED_BYTE, NULL);
	if (gl_error("gl_shmem_init_data", "failed to set texture data")) {
		return false;
	}

	return true;
}

static inline bool gl_shmem_init_buffers(void)
{
	uint32_t size = data.cx * data.cy * 4;
	GLint last_pbo;
	GLint last_tex;

	glGenBuffers(NUM_BUFFERS, data.pbos);
	if (gl_error("gl_shmem_init_buffers", "failed to generate buffers")) {
		return false;
	}

	glGenTextures(NUM_BUFFERS, data.textures);
	if (gl_error("gl_shmem_init_buffers", "failed to generate textures")) {
		return false;
	}

	glGetIntegerv(GL_PIXEL_PACK_BUFFER_BINDING, &last_pbo);
	if (gl_error("gl_shmem_init_buffers",
				"failed to save pixel pack buffer")) {
		return false;
	}

	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_tex);
	if (gl_error("gl_shmem_init_buffers", "failed to save texture")) {
		return false;
	}

	for (size_t i = 0; i < NUM_BUFFERS; i++) {
		if (!gl_shmem_init_data(i, size)) {
			return false;
		}
	}

	glBindBuffer(GL_PIXEL_PACK_BUFFER, last_pbo);
	glBindTexture(GL_TEXTURE_2D, last_tex);
	return true;
}

static bool gl_shmem_init(HWND window)
{
	if (!gl_shmem_init_buffers()) {
		return false;
	}
	if (!gl_init_fbo()) {
		return false;
	}
	if (!capture_init_shmem(&data.shmem_info, window,
				data.base_cx, data.base_cy, data.cx, data.cy,
				data.cx * 4, data.format, true)) {
		return false;
	}

	hlog("gl memory capture successful");
	return true;
}

static void gl_init(HDC hdc)
{
	HWND window = WindowFromDC(hdc);
	bool success = false;
	RECT rc = {0};

	GetClientRect(window, &rc);

	data.base_cx = rc.right;
	data.base_cy = rc.bottom;
	data.hdc = hdc;
	data.format = DXGI_FORMAT_B8G8R8A8_UNORM;
	data.using_scale = global_hook_info->use_scale;
	data.using_shtex = nv_capture_available &&
		!global_hook_info->force_shmem;

	if (data.using_scale) {
		data.cx = global_hook_info->cx;
		data.cy = global_hook_info->cy;
	} else {
		data.cx = data.base_cx;
		data.cy = data.base_cy;
	}

	if (data.using_shtex)
		success = gl_shtex_init(window);
	else
		success = gl_shmem_init(window);

	if (!success)
		gl_free();
}

static void gl_copy_backbuffer(GLuint dst)
{
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, data.fbo);
	if (gl_error("gl_shtex_capture_blit", "failed to bind FBO")) {
		return;
	}

	glBindTexture(GL_TEXTURE_2D, dst);
	if (gl_error("gl_shtex_capture_blit", "failed to bind texture")) {
		return;
	}

	glFramebufferTexture2D(GL_DRAW_FRAMEBUFFER, GL_COLOR_ATTACHMENT0,
			GL_TEXTURE_2D, dst, 0);
	if (gl_error("gl_shtex_capture_blit", "failed to set frame buffer")) {
		return;
	}

	glReadBuffer(GL_BACK);
	if (gl_error("gl_shtex_capture_blit", "failed to set read buffer")) {
		return;
	}

	glDrawBuffer(GL_COLOR_ATTACHMENT0);
	if (gl_error("gl_shtex_capture_blit", "failed to set draw buffer")) {
		return;
	}

	glBlitFramebuffer(0, 0, data.base_cx, data.base_cy,
			0, 0, data.cx, data.cy, GL_COLOR_BUFFER_BIT, GL_LINEAR);
	gl_error("gl_shtex_capture_blit", "failed to blit");
}

static void gl_shtex_capture(void)
{
	GLint last_fbo;
	GLint last_tex;

	jimglDXLockObjectsNV(data.gl_device, 1, &data.gl_dxobj);

	glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &last_fbo);
	if (gl_error("gl_shtex_capture", "failed to get last fbo")) {
		return;
	}

	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_tex);
	if (gl_error("gl_shtex_capture", "failed to get last texture")) {
		return;
	}

	gl_copy_backbuffer(data.texture);

	glBindTexture(GL_TEXTURE_2D, last_tex);
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, last_fbo);

	jimglDXUnlockObjectsNV(data.gl_device, 1, &data.gl_dxobj);

	IDXGISwapChain_Present(data.dxgi_swap, 0, 0);
}

static inline void gl_shmem_capture_queue_copy(void)
{
	for (int i = 0; i < NUM_BUFFERS; i++) {
		if (data.texture_ready[i]) {
			GLvoid *buffer;

			data.texture_ready[i] = false;

			glBindBuffer(GL_PIXEL_PACK_BUFFER, data.pbos[i]);
			if (gl_error("gl_shmem_capture_queue_copy",
						"failed to bind pbo")) {
				return;
			}

			buffer = glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
			if (buffer) {
				data.texture_mapped[i] = true;
				shmem_copy_data(i, buffer);
			}
			break;
		}
	}
}

static inline void gl_shmem_capture_stage(GLuint dst_pbo, GLuint src_tex)
{
	glBindTexture(GL_TEXTURE_2D, src_tex);
	if (gl_error("gl_shmem_capture_stage", "failed to bind src_tex")) {
		return;
	}

	glBindBuffer(GL_PIXEL_PACK_BUFFER, dst_pbo);
	if (gl_error("gl_shmem_capture_stage", "failed to bind dst_pbo")) {
		return;
	}

	glGetTexImage(GL_TEXTURE_2D, 0, GL_BGRA, GL_UNSIGNED_BYTE, 0);
	if (gl_error("gl_shmem_capture_stage", "failed to read src_tex")) {
		return;
	}
}

static void gl_shmem_capture(void)
{
	int next_tex;
	GLint last_fbo;
	GLint last_tex;

	glGetIntegerv(GL_DRAW_FRAMEBUFFER_BINDING, &last_fbo);
	if (gl_error("gl_shmem_capture", "failed to get last fbo")) {
		return;
	}

	glGetIntegerv(GL_TEXTURE_BINDING_2D, &last_tex);
	if (gl_error("gl_shmem_capture", "failed to get last texture")) {
		return;
	}

	gl_shmem_capture_queue_copy();

	next_tex = (data.cur_tex == NUM_BUFFERS - 1) ? 0 : data.cur_tex + 1;

	gl_copy_backbuffer(data.textures[next_tex]);

	if (data.copy_wait < NUM_BUFFERS - 1) {
		data.copy_wait++;
	} else {
		GLuint src = data.textures[next_tex];
		GLuint dst = data.pbos[next_tex];

		if (shmem_texture_data_lock(next_tex)) {
			glUnmapBuffer(GL_PIXEL_PACK_BUFFER);
			data.texture_mapped[next_tex] = false;
			shmem_texture_data_unlock(next_tex);
		}

		gl_shmem_capture_stage(dst, src);
		data.texture_ready[next_tex] = true;
	}

	glBindTexture(GL_TEXTURE_2D, last_tex);
	glBindFramebuffer(GL_DRAW_FRAMEBUFFER, last_fbo);
}

static void gl_capture(HDC hdc)
{
	static bool functions_initialized = false;
	static bool critical_failure = false;

	if (critical_failure) {
		return;
	}

	if (!functions_initialized) {
		functions_initialized = init_gl_functions();
		if (!functions_initialized) {
			critical_failure = true;
			return;
		}
	}

	if (capture_should_stop()) {
		gl_free();
	}
	if (capture_should_init()) {
		gl_init(hdc);
	}
	if (capture_ready() && hdc == data.hdc) {
		uint32_t new_cx;
		uint32_t new_cy;

		/* reset capture if resized */
		get_window_size(hdc, &new_cx, &new_cy);
		if (new_cx != data.base_cx || new_cy != data.base_cy) {
			gl_free();
			return;
		}

		if (data.using_shtex)
			gl_shtex_capture();
		else
			gl_shmem_capture();
	}
}

static BOOL WINAPI hook_swap_buffers(HDC hdc)
{
	BOOL ret;

	if (!global_hook_info->capture_overlay)
		gl_capture(hdc);

	unhook(&swap_buffers);
	BOOL (WINAPI *call)(HDC) = swap_buffers.call_addr;
	ret = call(hdc);
	rehook(&swap_buffers);

	if (global_hook_info->capture_overlay)
		gl_capture(hdc);

	return ret;
}

static BOOL WINAPI hook_wgl_swap_buffers(HDC hdc)
{
	BOOL ret;

	if (!global_hook_info->capture_overlay)
		gl_capture(hdc);

	unhook(&wgl_swap_buffers);
	BOOL (WINAPI *call)(HDC) = wgl_swap_buffers.call_addr;
	ret = call(hdc);
	rehook(&wgl_swap_buffers);

	if (global_hook_info->capture_overlay)
		gl_capture(hdc);

	return ret;
}

static BOOL WINAPI hook_wgl_swap_layer_buffers(HDC hdc, UINT planes)
{
	BOOL ret;

	if (!global_hook_info->capture_overlay)
		gl_capture(hdc);

	unhook(&wgl_swap_layer_buffers);
	BOOL (WINAPI *call)(HDC, UINT) = wgl_swap_layer_buffers.call_addr;
	ret = call(hdc, planes);
	rehook(&wgl_swap_layer_buffers);

	if (global_hook_info->capture_overlay)
		gl_capture(hdc);

	return ret;
}

static BOOL WINAPI hook_wgl_delete_context(HGLRC hrc)
{
	BOOL ret;

	if (capture_active()) {
		HDC last_hdc = jimglGetCurrentDC();
		HGLRC last_hrc = jimglGetCurrentContext();

		jimglMakeCurrent(data.hdc, hrc);
		gl_free();
		jimglMakeCurrent(last_hdc, last_hrc);
	}

	unhook(&wgl_delete_context);
	BOOL (WINAPI *call)(HGLRC) = wgl_delete_context.call_addr;
	ret = call(hrc);
	rehook(&wgl_delete_context);

	return ret;
}

static bool gl_register_window(void)
{
	WNDCLASSW wc = {0};
	wc.style = CS_OWNDC;
	wc.hInstance = GetModuleHandle(NULL);
	wc.lpfnWndProc = DefWindowProc;
	wc.lpszClassName = DUMMY_WINDOW_CLASS_NAME;

	if (!RegisterClassW(&wc)) {
		hlog("gl_register_window: failed to register window class: %d",
				GetLastError());
		return false;
	}

	return true;
}

bool hook_gl(void)
{
	void *wgl_dc_proc;
	void *wgl_slb_proc;
	void *wgl_sb_proc;

	gl = get_system_module("opengl32.dll");
	if (!gl) {
		return false;
	}

	if (!gl_register_window()) {
		return true;
	}

	wgl_dc_proc = base_get_proc("wglDeleteContext");
	wgl_slb_proc = base_get_proc("wglSwapLayerBuffers");
	wgl_sb_proc = base_get_proc("wglSwapBuffers");

	hook_init(&swap_buffers, SwapBuffers, hook_swap_buffers, "SwapBuffers");
	if (wgl_dc_proc) {
		hook_init(&wgl_delete_context, wgl_dc_proc,
				hook_wgl_delete_context,
				"wglDeleteContext");
		rehook(&wgl_delete_context);
	}
	if (wgl_slb_proc) {
		hook_init(&wgl_swap_layer_buffers, wgl_slb_proc,
				hook_wgl_swap_layer_buffers,
				"wglSwapLayerBuffers");
		rehook(&wgl_swap_layer_buffers);
	}
	if (wgl_sb_proc) {
		hook_init(&wgl_swap_buffers, wgl_sb_proc,
				hook_wgl_swap_buffers,
				"wglSwapBuffers");
		rehook(&wgl_swap_buffers);
	}

	rehook(&swap_buffers);

	return true;
}