obs-studio/libobs-opengl/gl-x11.c

#include <X11/Xlib.h>

#include <stdio.h>

#include "gl-subsystem.h"

#include <GL/glx.h>
#include <GL/glxext.h>
	
static PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribsARB;
	
static const GLenum fb_attribs[] = {
	/* Hardcoded for now... */
	GLX_STENCIL_SIZE, 8,
	GLX_DEPTH_SIZE, 24, 
	GLX_BUFFER_SIZE, 32, /* Color buffer depth */
	GLX_DOUBLEBUFFER, True,
	None
};

static const GLenum ctx_attribs[] = {
#ifdef _DEBUG
	GLX_CONTEXT_FLAGS_ARB, GLX_CONTEXT_DEBUG_BIT_ARB,
#endif
	GLX_CONTEXT_PROFILE_MASK_ARB, GLX_CONTEXT_CORE_PROFILE_BIT_ARB,
	None, 
};

struct gl_windowinfo {
	uint32_t id;
	Display *display;
};
	
struct gl_platform {
	GLXContext context;
	struct gs_swap_chain swap;
};

extern struct gs_swap_chain *gl_platform_getswap(struct gl_platform *platform) 
{
	return &platform->swap;
}

extern struct gl_windowinfo *gl_windowinfo_create(struct gs_init_data *info) 
{
	struct gl_windowinfo *wi = bmalloc(sizeof(struct gl_windowinfo));
	memset(wi, 0, sizeof(struct gl_windowinfo));
	
	wi->id = info->window.id;
	/* wi->display = info->window.display; */

	/*
		In order to do the above, we have to call
		XInitThreads in the soonest possible time. 
		The wxFrame initializer is good but it sucks
		big time that I'm having to make X11 specific
		code all over platform-independent code. 

		The solution we have now avoids this although I'd
		like to be able to do the above as it's probably
		safer (I don't know the side-effects of using a Display
		connection that wasn't used to create the window)
		and more efficient. 
	 */
	
	return wi;
}

extern void gl_windowinfo_destroy(struct gl_windowinfo *wi) 
{
	bfree(wi);
}

extern void gl_getclientsize(struct gs_swap_chain *swap,
			     uint32_t *width, uint32_t *height) 
{
	XWindowAttributes info = { 0 };
	
	XGetWindowAttributes(swap->wi->display, swap->wi->id, &info);
	
	*height = info.height;
	*width = info.width;
}

static void print_info_stuff(struct gs_init_data *info)
{
	blog(	LOG_INFO,
		"X and Y: %i %i\n"
		"Backbuffers: %i\n"
		"Color Format: %i\n"
		"ZStencil Format: %i\n"
		"Adapter: %i\n",
		info->cx, info->cy, 
		info->num_backbuffers,
		info->format, info->zsformat, 
		info->adapter
	);
}

struct gl_platform *gl_platform_create(device_t device,
		struct gs_init_data *info)
{	
	int num_configs = 0;
	int error_base = 0, event_base = 0;
	Display *display = XOpenDisplay(NULL); /* Open default screen */
	struct gl_platform *plat = bmalloc(sizeof(struct gl_platform));
	GLXFBConfig* configs;
	
	print_info_stuff(info);
	
	memset(plat, 0, sizeof(struct gl_platform));
	
	if (!display) {
		blog(LOG_ERROR, "Unable to find display. DISPLAY variable may not be set correctly.");
		goto fail0;
	}
	
	
	if (!glXQueryExtension(display, &error_base, &event_base)) {
		blog(LOG_ERROR, "GLX not supported.");
		goto fail0;
	}
	
	/* We require glX version 1.4 */
	{
		int major = 0, minor = 0;
		
		glXQueryVersion(display, &major, &minor);
		if (major < 1 || minor < 4) {
			blog(LOG_ERROR, "GLX version found: %i.%i\nRequired: 1.4", major, minor);
			goto fail0;
		}
	}
	
	glXCreateContextAttribsARB = (PFNGLXCREATECONTEXTATTRIBSARBPROC)glXGetProcAddress("glXCreateContextAttribsARB");
	if (!glXCreateContextAttribsARB) {
		blog(LOG_ERROR, "ARB_GLX_create_context not supported!");
		goto fail0;
	}
	
	configs = glXChooseFBConfig(display, DefaultScreen(display), fb_attribs, &num_configs);

	if(!configs) {
		blog(LOG_ERROR, "Attribute list or screen is invalid.");
		goto fail0;
	}
	
	if(num_configs == 0) {
		blog(LOG_ERROR, "No framebuffer configurations found.");
		goto fail1;
	}
	
	/* We just use the first configuration found... as it does everything we want at the very least. */
	plat->context = glXCreateContextAttribsARB(display, configs[0], NULL, True, ctx_attribs);
	if(!plat->context) { 
		blog(LOG_ERROR, "Failed to create OpenGL context.");
		goto fail1;
	}
	
	if(!glXMakeCurrent(display, info->window.id, plat->context)) {
		blog(LOG_ERROR, "Failed to make context current.");
		goto fail2;
	}

	/* Initialize GLEW */
	{ 	
		glewExperimental = true;
		GLenum err = glewInit();
		
		if (GLEW_OK != err) {
			blog(LOG_ERROR, glewGetErrorString(err));
			goto fail2;
		}
	}
	
	blog(LOG_INFO, "OpenGL version: %s\n", glGetString(GL_VERSION));
	
	plat->swap.device = device;
	plat->swap.info	  = *info;
	plat->swap.wi     = gl_windowinfo_create(info);
	plat->swap.wi->display = display;
	
	XFree(configs);
	XSync(display, False);
	
	return plat;
	
fail2:
	glXMakeCurrent(display, None, NULL);
	glXDestroyContext(display, plat->context);
fail1: 
	XFree(configs);
fail0:
	bfree(plat);
	return NULL;
}

extern void gl_platform_destroy(struct gl_platform *platform) 
{
	if (!platform)
		return; 
	
	glXMakeCurrent(platform->swap.wi->display, None, NULL);
	glXDestroyContext(platform->swap.wi->display, platform->context);
	XCloseDisplay(platform->swap.wi->display);
	gl_windowinfo_destroy(platform->swap.wi);
	bfree(platform);
}

void device_entercontext(device_t device) 
{
	GLXContext context = device->plat->context;
	XID window = device->plat->swap.wi->id;
	Display *display = device->plat->swap.wi->display;
	
	if (device->cur_swap)
		 device->plat->swap.wi->id = device->cur_swap->wi->id;
	
	if (!glXMakeCurrent(display, window, context)) {
		blog(LOG_ERROR, "Failed to make context current.");
	}
}
void device_leavecontext(device_t device) 
{
	Display *display = device->plat->swap.wi->display;
	
	if(!glXMakeCurrent(display, None, NULL)) { 
		blog(LOG_ERROR, "Failed to reset current context.");
	}
}

void gl_update(device_t device)
{
	/* I don't know of anything we can do here. */
}

void device_load_swapchain(device_t device, swapchain_t swap) 
{
	if(!swap)
		swap = &device->plat->swap;
	
	device->cur_swap = swap;
}

void device_present(device_t device) 
{
	Display *display = device->plat->swap.wi->display;
	XID window = device->plat->swap.wi->id;
	
	glXSwapBuffers(display, window);
}