From: Mikko Rasa <tdb@tdb.fi>
Date: Wed, 2 Nov 2016 21:23:35 +0000 (+0200)
Subject: Support forward-compatible OpenGL contexts
X-Git-Url: http://git.tdb.fi/?p=libs%2Fgui.git;a=commitdiff_plain;h=018da17591533b034d6bf018d2a9ac640007575e

Support forward-compatible OpenGL contexts
---

diff --git a/source/graphics/glcontext.cpp b/source/graphics/glcontext.cpp
index 47e1e59..df6ad60 100644
--- a/source/graphics/glcontext.cpp
+++ b/source/graphics/glcontext.cpp
@@ -12,13 +12,16 @@ GLOptions::GLOptions():
 	alpha(false),
 	stencil(false),
 	doublebuffer(true),
-	multisample(0)
+	multisample(0),
+	forward_compatible(false),
+	gl_version_major(0),
+	gl_version_minor(0)
 { }
 
 
 unsupported_gl_mode::unsupported_gl_mode(const GLOptions &opts):
-	runtime_error(format("{ .alpha=%s, .stencil=%s, .doublebuffer=%s, .multisample=%d }",
-		opts.alpha, opts.stencil, opts.doublebuffer, opts.multisample))
+	runtime_error(format("{ .alpha=%s, .stencil=%s, .doublebuffer=%s, .multisample=%d, .forward_compatible=%s, .gl_version=%d.%d }",
+		opts.alpha, opts.stencil, opts.doublebuffer, opts.multisample, opts.forward_compatible, opts.gl_version_major, opts.gl_version_minor))
 { }
 
 
diff --git a/source/graphics/glcontext.h b/source/graphics/glcontext.h
index 8cf75c8..8c8b499 100644
--- a/source/graphics/glcontext.h
+++ b/source/graphics/glcontext.h
@@ -15,6 +15,9 @@ struct GLOptions
 	bool stencil;
 	bool doublebuffer;
 	unsigned multisample;
+	bool forward_compatible;
+	unsigned gl_version_major;
+	unsigned gl_version_minor;
 
 	GLOptions();
 };
diff --git a/source/graphics/glx/glcontext.cpp b/source/graphics/glx/glcontext.cpp
index 46da6d1..5f04e3b 100644
--- a/source/graphics/glx/glcontext.cpp
+++ b/source/graphics/glx/glcontext.cpp
@@ -1,6 +1,8 @@
+#include <set>
 #include <vector>
-#include <GL/gl.h>
 #include <GL/glx.h>
+#include <GL/glxext.h>
+#include <msp/strings/utils.h>
 #include "glcontext.h"
 #include "display_private.h"
 #include "window_private.h"
@@ -17,67 +19,189 @@ struct GLContext::Private
 	ContextHandle context;
 	// We need to create a window with the chosen visual
 	WindowHandle subwnd;
+	GLXWindow glxwnd;
 };
 
 
 void GLContext::platform_init(const GLOptions &opts)
 {
-	vector<int> attribs;
+	DisplayHandle dpy = display.get_private().display;
+	int event_base;
+	int error_base;
+	if(!glXQueryExtension(dpy, &event_base, &error_base))
+		throw runtime_error("glX not found");
 
-	attribs.push_back(GLX_RGBA);
-	attribs.push_back(GLX_DEPTH_SIZE);
-	attribs.push_back(1);
+	int major, minor;
+	glXQueryVersion(dpy, &major, &minor);
 
-	if(opts.alpha)
+	set<string> extensions;
+	if(major>1 || (major==1 && minor>=1))
 	{
-		attribs.push_back(GLX_ALPHA_SIZE);
-		attribs.push_back(1);
+		if(const char *ext_str = glXQueryExtensionsString(dpy, DefaultScreen(dpy)))
+		{
+			vector<string> exts = split(ext_str);
+			extensions.insert(exts.begin(), exts.end());
+		}
 	}
 
-	if(opts.stencil)
+	if(major>1 || (major==1 && minor>=3))
 	{
-		attribs.push_back(GLX_STENCIL_SIZE);
-		attribs.push_back(1);
-	}
+		vector<int> fb_attribs;
+
+		fb_attribs.push_back(GLX_DRAWABLE_TYPE);
+		fb_attribs.push_back(GLX_WINDOW_BIT);
+
+		fb_attribs.push_back(GLX_RENDER_TYPE);
+		fb_attribs.push_back(GLX_RGBA_BIT);
+
+		fb_attribs.push_back(GLX_DEPTH_SIZE);
+		fb_attribs.push_back(1);
+
+		if(opts.alpha)
+		{
+			fb_attribs.push_back(GLX_ALPHA_SIZE);
+			fb_attribs.push_back(1);
+		}
+
+		if(opts.stencil)
+		{
+			fb_attribs.push_back(GLX_STENCIL_SIZE);
+			fb_attribs.push_back(1);
+		}
+
+		fb_attribs.push_back(GLX_DOUBLEBUFFER);
+		fb_attribs.push_back(opts.doublebuffer);
+
+		if(opts.multisample>0)
+		{
+			fb_attribs.push_back(GLX_SAMPLE_BUFFERS_ARB);
+			fb_attribs.push_back(1);
+			fb_attribs.push_back(GLX_SAMPLES_ARB);
+			fb_attribs.push_back(opts.multisample);
+		}
+
+		fb_attribs.push_back(0);
+
+		int n_configs = 0;
+		GLXFBConfig *fb_configs = glXChooseFBConfig(dpy, DefaultScreen(dpy), &fb_attribs[0], &n_configs);
+		if(!fb_configs)
+			throw unsupported_gl_mode(opts);
+
+		XVisualInfo *vi = glXGetVisualFromFBConfig(dpy, fb_configs[0]);
+
+		XSetWindowAttributes attr;
+		attr.colormap = XCreateColormap(dpy, DefaultRootWindow(dpy), vi->visual, AllocNone);
+
+		priv = new Private;
+		priv->subwnd = XCreateWindow(dpy, window.get_private().window, 0, 0, window.get_width(), window.get_height(), 0, vi->depth, InputOutput, vi->visual, CWColormap, &attr);
+		XMapWindow(dpy, priv->subwnd);
+
+		priv->glxwnd = glXCreateWindow(dpy, fb_configs[0], priv->subwnd, 0);
+
+		if(opts.forward_compatible || opts.gl_version_major)
+		{
+			if(!extensions.count("GLX_ARB_create_context") || !extensions.count("GLX_ARB_get_proc_address"))
+				throw unsupported_gl_mode(opts);
 
-	if(opts.doublebuffer)
-		attribs.push_back(GLX_DOUBLEBUFFER);
+			vector<int> ctx_attribs;
 
-	if(opts.multisample>0)
+			ctx_attribs.push_back(GLX_RENDER_TYPE);
+			ctx_attribs.push_back(GLX_RGBA_TYPE);
+
+			if(opts.forward_compatible)
+			{
+				ctx_attribs.push_back(GLX_CONTEXT_FLAGS_ARB);
+				ctx_attribs.push_back(GLX_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB);
+			}
+
+			if(opts.gl_version_major)
+			{
+				ctx_attribs.push_back(GLX_CONTEXT_MAJOR_VERSION_ARB);
+				ctx_attribs.push_back(opts.gl_version_major);
+				ctx_attribs.push_back(GLX_CONTEXT_MINOR_VERSION_ARB);
+				ctx_attribs.push_back(opts.gl_version_minor);
+			}
+
+			ctx_attribs.push_back(0);
+
+			const GLubyte *name = reinterpret_cast<const GLubyte *>("glXCreateContextAttribsARB");
+			PFNGLXCREATECONTEXTATTRIBSARBPROC glXCreateContextAttribs = reinterpret_cast<PFNGLXCREATECONTEXTATTRIBSARBPROC>(glXGetProcAddressARB(name));
+			priv->context = glXCreateContextAttribs(dpy, fb_configs[0], 0, true, &ctx_attribs[0]);
+		}
+		else
+			priv->context = glXCreateNewContext(dpy, fb_configs[0], GLX_RGBA_TYPE, 0, true);
+
+		XFree(vi);
+		XFree(fb_configs);
+
+		glXMakeContextCurrent(dpy, priv->glxwnd, priv->glxwnd, priv->context);
+	}
+	else if(opts.forward_compatible || opts.gl_version_major)
+		throw unsupported_gl_mode(opts);
+	else
 	{
-		attribs.push_back(GLX_SAMPLE_BUFFERS_ARB);
+		vector<int> attribs;
+
+		attribs.push_back(GLX_RGBA);
+		attribs.push_back(GLX_DEPTH_SIZE);
 		attribs.push_back(1);
-		attribs.push_back(GLX_SAMPLES_ARB);
-		attribs.push_back(opts.multisample);
-	}
 
-	attribs.push_back(0);
+		if(opts.alpha)
+		{
+			attribs.push_back(GLX_ALPHA_SIZE);
+			attribs.push_back(1);
+		}
 
-	DisplayHandle dpy = display.get_private().display;
+		if(opts.stencil)
+		{
+			attribs.push_back(GLX_STENCIL_SIZE);
+			attribs.push_back(1);
+		}
 
-	XVisualInfo *vi = glXChooseVisual(dpy, DefaultScreen(dpy), &attribs.front());
-	if(!vi)
-		throw unsupported_gl_mode(opts);
+		if(opts.doublebuffer)
+			attribs.push_back(GLX_DOUBLEBUFFER);
+
+		if(opts.multisample>0)
+		{
+			attribs.push_back(GLX_SAMPLE_BUFFERS_ARB);
+			attribs.push_back(1);
+			attribs.push_back(GLX_SAMPLES_ARB);
+			attribs.push_back(opts.multisample);
+		}
+
+		attribs.push_back(0);
 
-	priv = new Private;
-	priv->context = glXCreateContext(dpy, vi, 0, true);
+		XVisualInfo *vi = glXChooseVisual(dpy, DefaultScreen(dpy), &attribs.front());
+		if(!vi)
+			throw unsupported_gl_mode(opts);
 
-	XSetWindowAttributes attr;
-	attr.colormap = XCreateColormap(dpy, DefaultRootWindow(dpy), vi->visual, AllocNone);
+		priv = new Private;
+		priv->glxwnd = 0;
+		priv->context = glXCreateContext(dpy, vi, 0, true);
 
-	priv->subwnd = XCreateWindow(dpy, window.get_private().window, 0, 0, window.get_width(), window.get_height(), 0, vi->depth, InputOutput, vi->visual, CWColormap, &attr);
-	XMapWindow(dpy, priv->subwnd);
+		XSetWindowAttributes attr;
+		attr.colormap = XCreateColormap(dpy, DefaultRootWindow(dpy), vi->visual, AllocNone);
 
-	XFree(vi);
+		priv->subwnd = XCreateWindow(dpy, window.get_private().window, 0, 0, window.get_width(), window.get_height(), 0, vi->depth, InputOutput, vi->visual, CWColormap, &attr);
+		XMapWindow(dpy, priv->subwnd);
 
-	glXMakeCurrent(dpy, priv->subwnd, priv->context);
+		XFree(vi);
+
+		glXMakeCurrent(dpy, priv->subwnd, priv->context);
+	}
 }
 
 GLContext::~GLContext()
 {
 	DisplayHandle dpy = display.get_private().display;
 
-	glXMakeCurrent(dpy, 0, 0);
+	if(priv->glxwnd)
+	{
+		glXMakeContextCurrent(dpy, 0, 0, 0);
+		glXDestroyWindow(dpy, priv->glxwnd);
+	}
+	else
+		glXMakeCurrent(dpy, 0, 0);
 	glXDestroyContext(dpy, priv->context);
 	XDestroyWindow(dpy, priv->subwnd);
 
@@ -90,12 +214,12 @@ void GLContext::set_swap_interval(unsigned i)
 	PFNGLXSWAPINTERVALEXTPROC func = reinterpret_cast<PFNGLXSWAPINTERVALEXTPROC>(glXGetProcAddress(name));
 	if(!func)
 		throw runtime_error("glXSwapIntervalEXT not found");
-	func(display.get_private().display, priv->subwnd, i);
+	func(display.get_private().display, (priv->glxwnd ? priv->glxwnd : priv->subwnd), i);
 }
 
 void GLContext::swap_buffers()
 {
-	glXSwapBuffers(display.get_private().display, priv->subwnd);
+	glXSwapBuffers(display.get_private().display, (priv->glxwnd ? priv->glxwnd : priv->subwnd));
 }
 
 void GLContext::window_resized(unsigned w, unsigned h)
diff --git a/source/graphics/wgl/glcontext.cpp b/source/graphics/wgl/glcontext.cpp
index 3df83f3..6c378a6 100644
--- a/source/graphics/wgl/glcontext.cpp
+++ b/source/graphics/wgl/glcontext.cpp
@@ -42,7 +42,34 @@ void GLContext::platform_init(const GLOptions &opts)
 	SetPixelFormat(dc, pf_index, &pfd);
 
 	priv = new Private;
-	priv->context = wglCreateContext(dc);
+	if(opts.forward_compatible || opts.gl_version_major)
+	{
+		PFNWGLCREATECONTEXTATTRIBSARBPROC wglCreateContextAttribs = reinterpret_cast<PFNWGLCREATECONTEXTATTRIBSARBPROC>(wglGetProcAddress("wglCreateContextAttribs"));
+		if(!wglCreateContextAttribs)
+			throw unsupported_gl_mode(opts);
+
+		vector<int> ctx_attribs;
+
+		if(opts.forward_compatible)
+		{
+			ctx_attribs.push_back(WGL_CONTEXT_FLAGS_ARB);
+			ctx_attribs.push_back(WGL_CONTEXT_FORWARD_COMPATIBLE_BIT_ARB);
+		}
+
+		if(opts.gl_version_major)
+		{
+			ctx_attribs.push_back(WGL_CONTEXT_MAJOR_VERSION_ARB);
+			ctx_attribs.push_back(opts.gl_version_major);
+			ctx_attribs.push_back(WGL_CONTEXT_MINOR_VERSION_ARB);
+			ctx_attribs.push_back(opts.gl_version_minor);
+		}
+
+		ctx_attribs.push_back(0);
+
+		priv->context = wglCreateContextAttribs(dc, 0, &ctx_attribs[0]);
+	}
+	else
+		priv->context = wglCreateContext(dc);
 	wglMakeCurrent(dc, priv->context);
 
 	ReleaseDC(window.get_private().window, dc);