Platform specifics: Linux

This Section explains how to install Drivers to make OpenGL Programs run under Linux and how to use different Libraries/Toolkits to create Opengl Programs.

Mesa is an open-source OpenGL implementation, continually updated to support the latest OpenGL specification.

The Direct Rendering Infrastructure, also known as the DRI, is a framework for allowing direct access to graphics hardware under the X Window System in a safe and efficient manner.

http://dri.freedesktop.org/wiki/

Current version of EGL in Mesa implements EGL 1.4

http://mesa3d.org/egl.html

Mesa implements OpenGL ES 1.1 and OpenGL ES 2.0

http://mesa3d.org/opengles.html

Mesa 10.6.7 implements the OpenGL 3.3 API OpenGL 3.3 is only available if requested at context creation because compatibility contexts are not supported

http://mesa3d.org/relnotes/10.6.7.html

Big Picture (DRI)

mesa

Mesa is an open-source implementation of the OpenGL specification - a system for rendering interactive 3D graphics

Mesa ties into several other open-source projects: the Direct Rendering Infrastructure and X.org to provide OpenGL support to users of X on Linux, FreeBSD and other operating systems

http://www.mesa3d.org/intro.html

Checklist

• Direct Rendering Infrastructure [V]

Direct Rendering Infrastructure

Direct Rendering Infrastructure (DRI) is a framework for allowing direct access to graphics hardware under the X Window System in a safe, efficient way.[5] The main use of DRI is to provide hardware acceleration for the Mesa implementation of OpenGL

https://en.wikipedia.org/wiki/Direct_Rendering_Infrastructure

Mesa is an open-source OpenGL implementation, continually updated to support the latest OpenGL specification

Direct Rendering Infrastructure, also known as the DRI, is a framework for allowing direct access to graphics hardware under the X Window System in a safe and efficient manner. It includes changes to the X server, to several client libraries, and to the kernel (DRM, Direct Rendering Manager)

http://dri.freedesktop.org/wiki/

Checklist

• debian dri [V]
• debian drm [V]

debian dri

libgl1-mesa-dri (10.6.5-1 and others)

OpenGL API -- DRI modules

Mesa provides GLX and DRI capabilities: it is capable of both direct and indirect rendering. For direct rendering, it can use DRI modules from the libgl1-mesa-dri package to accelerate drawing

does not include the OpenGL library itself, only the DRI modules

dep: libdrm-nouveau2 Userspace interface to nouveau-specific kernel DRM services -- runtime

dep: libdrm2 Userspace interface to kernel DRM services -- runtime

Similar packages:

• libgl1-mesa-glx
• libegl1-mesa

https://packages.debian.org/sid/libgl1-mesa-dri

libegl1-mesa (10.6.5-1 and others)

EGL API -- runtime

contains the EGL native platform graphics interface library. EGL provides a platform-agnostic mechanism for creating rendering surfaces for use with other graphics libraries, such as OpenGL|ES

contains modules to interface with the existing system GLX or DRI2 drivers to provide OpenGL via EGL

https://packages.debian.org/sid/libegl1-mesa

/usr/lib/x86_64-linux-gnu/libEGL.so.1
/usr/lib/x86_64-linux-gnu/libEGL.so.1.0.0

https://packages.debian.org/sid/amd64/libegl1-mesa/filelist

debian drm

Direct Rendering Manager (DRM) is a subsystem of the Linux kernel responsible for interfacing with GPUs of modern video cards. DRM exposes an API that user space programs can use to send commands and data to the GPU, and perform operations such as configuring the mode setting of the display. DRM was first developed as the kernel space component of the X Server's Direct Rendering Infrastructure

https://en.wikipedia.org/wiki/Direct_Rendering_Manager

DRM is a kernel module that gives direct hardware access to DRI clients

module deals with DMA, AGP memory management, resource locking, and secure hardware access.

DRM supports the DRI in three major ways:

• DRM provides synchronized access to the graphics hardware
• DRM enforces the DRI security policy for access to the graphics hardware
• DRM provides a generic DMA engine

http://dri.freedesktop.org/wiki/DRM/

libdrm2 (2.4.64-1 and others)

Userspace interface to kernel DRM services -- runtime

DRM stands for "Direct Rendering Manager", which is the kernelspace portion of the "Direct Rendering Infrastructure" (DRI). The DRI is currently used on Linux to provide hardware-accelerated OpenGL drivers

Similar packages: ...

• libdrm-nouveau2

...

https://packages.debian.org/sid/libdrm2

/usr/lib/x86_64-linux-gnu/libdrm.so.2
/usr/lib/x86_64-linux-gnu/libdrm.so.2.4.0

https://packages.debian.org/sid/amd64/libdrm2/filelist

libdrm-nouveau2 (2.4.64-1 and others)

interface to nouveau-specific kernel DRM services -- runtime

implements the userspace interface to the kernel DRM services. DRM stands for "Direct Rendering Manager", which is the kernelspace portion of the "Direct Rendering Infrastructure" (DRI). The DRI is currently used on Linux to provide hardware-accelerated OpenGL drivers

https://packages.debian.org/sid/libdrm-nouveau2

/usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2
/usr/lib/x86_64-linux-gnu/libdrm_nouveau.so.2.0.0

https://packages.debian.org/sid/amd64/libdrm-nouveau2/filelist

Checklist

• linux drm [V]
• hardware acceleration [V]
• kernelspace
• userspace

linux drm

• DRM Core
  • Introduction
  • DRM Internals
    • Driver Initialization
    • Memory management
    • Mode Setting
    • KMS Initialization and Cleanup
    • Mode Setting Helper Functions
    • KMS Properties
    • Vertical Blanking
    • Open/Close, File Operations and IOCTLs
    • Legacy Support Code
  • Userland interfaces
• DRM Drivers

https://www.kernel.org/doc/htmldocs/drm/

hardware acceleration

hardware acceleration is the use of computer hardware to perform some functions faster than is possible in software running on a more general-purpose CPU. Examples of hardware acceleration include blitting acceleration functionality in graphics processing units (GPUs)

https://en.wikipedia.org/wiki/Hardware_acceleration

Mesa3D GL* through EGL & XCB

OpenGL ABI

• ABI (Application Binary Interface) and runtime environment for applications using OpenGL under X11 on Linux enable applications using the OpenGL API for rendering to run on a variety of underlying implementations transparently. The intent is to address all of open source, commercial closed binary, OpenGL SI-based, and Mesa-based implementations.

• SDK for developing apps using OpenGL. This includes header file locations, conventions for use of extensions, etc.

https://www.opengl.org/registry/ABI/

Some Linux distributions may include support for hardware acceleration. Also, some GPUs have Open Source drivers developed by the community even though a closed source driver may be available from the manufacturer.

Prerequisites

/usr/lib/x86_64-linux-gnu/libEGL.so.1
/usr/lib/x86_64-linux-gnu/libEGL.so.1.0.0
/usr/share/bug/libegl1-mesa/control
/usr/share/bug/libegl1-mesa/script
/usr/share/doc/libegl1-mesa/changelog.Debian.gz
/usr/share/doc/libegl1-mesa/copyright
/usr/share/lintian/overrides/libegl1-mesa

https://packages.debian.org/sid/amd64/libegl1-mesa/filelist

/usr/include/EGL/egl.h
/usr/include/EGL/eglext.h
/usr/include/EGL/eglextchromium.h
/usr/include/EGL/eglmesaext.h
/usr/include/EGL/eglplatform.h
/usr/include/KHR/khrplatform.h
/usr/lib/x86_64-linux-gnu/libEGL.so
/usr/lib/x86_64-linux-gnu/libwayland-egl.so
/usr/lib/x86_64-linux-gnu/pkgconfig/egl.pc
/usr/lib/x86_64-linux-gnu/pkgconfig/wayland-egl.pc
/usr/share/bug/libegl1-mesa-dev/control
/usr/share/bug/libegl1-mesa-dev/script
/usr/share/doc/libegl1-mesa-dev/changelog.Debian.gz
/usr/share/doc/libegl1-mesa-dev/copyright

https://packages.debian.org/sid/amd64/libegl1-mesa-dev/filelist

/usr/lib/x86_64-linux-gnu/libGLESv2.so.2
/usr/lib/x86_64-linux-gnu/libGLESv2.so.2.0.0
/usr/share/bug/libgles2-mesa/control
/usr/share/bug/libgles2-mesa/script
/usr/share/doc/libgles2-mesa/changelog.Debian.gz
/usr/share/doc/libgles2-mesa/copyright
/usr/share/lintian/overrides/libgles2-mesa

https://packages.debian.org/sid/amd64/libgles2-mesa/filelist

/usr/include/GLES2/gl2.h
/usr/include/GLES2/gl2ext.h
/usr/include/GLES2/gl2platform.h
/usr/include/GLES3/gl3.h
/usr/include/GLES3/gl31.h
/usr/include/GLES3/gl3ext.h
/usr/include/GLES3/gl3platform.h
/usr/lib/x86_64-linux-gnu/libGLESv2.so
/usr/lib/x86_64-linux-gnu/pkgconfig/glesv2.pc
/usr/share/bug/libgles2-mesa-dev/control
/usr/share/bug/libgles2-mesa-dev/script
/usr/share/doc/libgles2-mesa-dev/changelog.Debian.gz
/usr/share/doc/libgles2-mesa-dev/copyright

https://packages.debian.org/sid/amd64/libgles2-mesa-dev/filelist

Source Code

/*
MIT License
Copyright (c) 2015 Alex Cham

Permission is hereby granted, free of charge, to any person obtaining a copy of
this software and associated documentation files (the "Software"), to deal in
the Software without restriction, including without limitation the rights to
use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies
of the Software, and to permit persons to whom the Software is furnished to do
so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all
copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
SOFTWARE.


Very Dirty Code! Test Purposes Only!

 Why XCB?
 X protocol C-language Binding (XCB) is a replacement for Xlib
 http://xcb.freedesktop.org/

 Basic Graphics Programming With The XCB Library
 http://www.x.org/releases/X11R7.6/doc/libxcb/tutorial/index.html

 Introduction to managing client API rendering through the EGL API.
 https://www.khronos.org/registry/egl/sdk/docs/man/html/eglIntro.xhtml

 Linking
Invoking: GCC C++ Linker
g++  -o "EGL14XCBGLES20MakeCurrentContext"  ./src/EGL14XCBGLES20MakeCurrentContext.o   -lxcb -lEGL -lGLESv2

 See Also:
 Documentation for the X Window System
 http://www.x.org/releases/X11R7.6/doc/
 */

#include <stdlib.h>
//
#include <EGL/egl.h>
#include <GLES2/gl2.h>
//
#include <xcb/xcb.h>

xcb_window_t makeXcbWindow(uint16_t width, uint16_t height,
		xcb_visualid_t eglConfAttrVisualID) {

	xcb_connection_t *c;
	xcb_screen_t *screen;
	xcb_window_t win;

	/* Open the connection to the X server */
	c = xcb_connect(NULL, NULL);

	/* Get the first screen */
	screen = xcb_setup_roots_iterator(xcb_get_setup(c)).data;

	/* Ask for our window's Id */
	win = xcb_generate_id(c);

	/* Create the window */

	xcb_create_window(c,
	XCB_COPY_FROM_PARENT, win, screen->root, 0, 0, width, height, 10,
			XCB_WINDOW_CLASS_INPUT_OUTPUT, eglConfAttrVisualID, 0,
			NULL);

	/* Map the window on the screen */
	xcb_map_window(c, win);

	/* Make sure commands are sent before we pause, so window is shown */
	xcb_flush(c);

	return win;
}

int main(int argc, char ** argv) {

	//@FIXME Black screen & cursor problems sometimes...

	/* get an EGL display connection */
	EGLDisplay display;
	display = eglGetDisplay(EGL_DEFAULT_DISPLAY);
	/* initialize the EGL display connection */
	eglInitialize(display, NULL, NULL);

	/* get an appropriate EGL frame buffer configuration */
	/*
	 All attributes in attrib_list, including boolean attributes, are immediately
	 followed by the corresponding desired value. The list is terminated with EGL_NONE

	 https://www.khronos.org/registry/egl/sdk/docs/man/html/eglChooseConfig.xhtml
	 */
	static EGLint const attribute_list[] = {
	EGL_RED_SIZE, 1,
	EGL_GREEN_SIZE, 1,
	EGL_BLUE_SIZE, 1,
	EGL_NONE };

	EGLConfig config;
	EGLint num_config;
	eglChooseConfig(display, attribute_list, &config, 1, &num_config);

	/* create an EGL rendering context */
	/*
	 #define EGL_OPENGL_ES_API		0x30A0
	 #define EGL_OPENVG_API			0x30A1
	 #define EGL_OPENGL_API			0x30A2
	 */
	eglBindAPI(EGL_OPENGL_ES_API);
	/*
	 eglCreateContext — create a new EGL rendering context

	 attrib_list specifies a list of attributes for the context.
	 The list has the same structure as described for eglChooseConfig

	 https://www.khronos.org/registry/egl/sdk/docs/man/html/eglCreateContext.xhtml
	 */
	static const EGLint ctx_attribs[] = {
	EGL_CONTEXT_CLIENT_VERSION, 2,
	EGL_NONE };

	EGLContext context;
	context = eglCreateContext(display, config, EGL_NO_CONTEXT, ctx_attribs);

	//Request eglVisualID for native window
	EGLint eglConfAttrVisualID;
	if (!eglGetConfigAttrib(display, config, EGL_NATIVE_VISUAL_ID,
			&eglConfAttrVisualID)) {
		//printf("Error: eglGetConfigAttrib() failed\n");
		exit(1);
	}

///////////////////////////////////////////////////////////////////////////////
	/* create a native window */
	//native_window = createNativeWindow();
	uint16_t width = 640;
	uint16_t height = 480;
	NativeWindowType nativeWindow;
	nativeWindow = makeXcbWindow(width, height,
			(xcb_visualid_t) eglConfAttrVisualID);
///////////////////////////////////////////////////////////////////////////////

	/* create an EGL window surface */
	EGLSurface surface;
	surface = eglCreateWindowSurface(display, config, nativeWindow, NULL);

	/* connect the context to the surface */
	eglMakeCurrent(display, surface, surface, context);

	/* clear the color buffer */
	while (1) {
		glViewport(0, 0, (GLsizei) width, (GLsizei) height);
		glClearColor(0., 0., 1., 0.);
		glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
		glFlush();
		eglSwapBuffers(display, surface);
	}

	return EXIT_SUCCESS;
}

See Also

• OpenGL in Linux: Driver Installation
• OpenGL in Linux: Programming
• SwapInterval aka vsync