As you know, GLUT itself has been frozen in time but it has a updated and extended opensource replacement freeglut. I have been using the latest SVN recently which contains the ability to create an ogl3 context. However, there is a new stable release that I haven’t tried yet “Freeglut 2.6.0 [Released: 27 November 2009]” that you could update to and try. – I will try it too when I get a chance since it would be nice to be using a stable branch instead of testing their SVN unstable branch all the time.
There is an example in the 2.6.0 release which shows how to get a 3.1 context … freeglut-2.6.0/progs/demos/smooth_opengl3/ pay particular attention to the following header line and two lines in the smooth_opengl3.c
#include <GL/freeglut.h>
...
glutInitContextVersion (3, 1);
glutInitContextFlags (GLUT_FORWARD_COMPATIBLE | GLUT_DEBUG);
Since ubuntu isn’t up to date with this latest version, what I do is compile freeglut-2.6 to a local folder (this way I don’t clobber the system wide freeglut to be safe for now)
download and extract tarball (2.6 version)
tar zxvf freeglut-2.6.0.tar.gz
cd freeglut-2.6.0
./configure --prefix ~/external/freeglut
make
make install
cd
progs/demos/smooth_opengl3
./smooth_opengl3
!!! you will see a gl3.1 example running :)
... with my method, the headers and lib files ended up in ~/external/freeglut
ls ~/external/freeglut
so to compile your own foo.cpp code you have to explicit where and which headers to use ...
the compile command line becomes
g++ foo.cpp -I$HOME/external/freeglut/include/ $HOME/external/freeglut/lib/libglut.a -lX11 -lGL -lXxf86vm
I consider this a temporary solution that will be cleaner when ubuntu catches up to the 2.6 release!
Note, I use gl3.h from openGL registry to replace the initExtensionEntries() and other related crust – freglut did it that way to avoid having extra libraries in their source examples. And that example code consequently mangles glFunction names as gl_function name – I don’t like this so here is my more “standard” code if you like
/*
* smooth_opengl3.c, based on smooth.c, which is (c) by SGI, see below.
* This program demonstrates smooth shading in a way which is fully
* OpenGL-3.1-compliant.
* A smooth shaded polygon is drawn in a 2-D projection.
*/
/*
* Original copyright notice from smooth.c:
*
* License Applicability. Except to the extent portions of this file are
* made subject to an alternative license as permitted in the SGI Free
* Software License B, Version 1.1 (the "License"), the contents of this
* file are subject only to the provisions of the License. You may not use
* this file except in compliance with the License. You may obtain a copy
* of the License at Silicon Graphics, Inc., attn: Legal Services, 1600
* Amphitheatre Parkway, Mountain View, CA 94043-1351, or at:
*
* http://oss.sgi.com/projects/FreeB
*
* Note that, as provided in the License, the Software is distributed on an
* "AS IS" basis, with ALL EXPRESS AND IMPLIED WARRANTIES AND CONDITIONS
* DISCLAIMED, INCLUDING, WITHOUT LIMITATION, ANY IMPLIED WARRANTIES AND
* CONDITIONS OF MERCHANTABILITY, SATISFACTORY QUALITY, FITNESS FOR A
* PARTICULAR PURPOSE, AND NON-INFRINGEMENT.
*
* Original Code. The Original Code is: OpenGL Sample Implementation,
* Version 1.2.1, released January 26, 2000, developed by Silicon Graphics,
* Inc. The Original Code is Copyright (c) 1991-2000 Silicon Graphics, Inc.
* Copyright in any portions created by third parties is as indicated
* elsewhere herein. All Rights Reserved.
*
* Additional Notice Provisions: The application programming interfaces
* established by SGI in conjunction with the Original Code are The
* OpenGL(R) Graphics System: A Specification (Version 1.2.1), released
* April 1, 1999; The OpenGL(R) Graphics System Utility Library (Version
* 1.3), released November 4, 1998; and OpenGL(R) Graphics with the X
* Window System(R) (Version 1.3), released October 19, 1998. This software
* was created using the OpenGL(R) version 1.2.1 Sample Implementation
* published by SGI, but has not been independently verified as being
* compliant with the OpenGL(R) version 1.2.1 Specification.
*
*/
#define GL3_PROTOTYPES
#include <GL3/gl3.h>
#include <GL/freeglut.h>
#include <stdlib.h>
#include <stdio.h>
#include <stddef.h>
#include <string.h>
/* report GL errors, if any, to stderr */
void checkError(const char *functionName)
{
GLenum error;
while (( error = glGetError() ) != GL_NO_ERROR) {
fprintf (stderr, "GL error 0x%X detected in %s
", error, functionName);
}
}
/* vertex array data for a colored 2D triangle, consisting of RGB color values
and XY coordinates */
const GLfloat varray[] = {
1.0f, 0.0f, 0.0f, /* red */
5.0f, 5.0f, /* lower left */
0.0f, 1.0f, 0.0f, /* green */
25.0f, 5.0f, /* lower right */
0.0f, 0.0f, 1.0f, /* blue */
5.0f, 25.0f /* upper left */
};
/* ISO C somehow enforces this silly use of 'enum' for compile-time constants */
enum {
numColorComponents = 3,
numVertexComponents = 2,
stride = sizeof(GLfloat) * (numColorComponents + numVertexComponents),
numElements = sizeof(varray) / stride
};
/* the name of the vertex buffer object */
GLuint vertexBufferName;
void initBuffer(void)
{
glGenBuffers (1, &vertexBufferName);
glBindBuffer (GL_ARRAY_BUFFER, vertexBufferName);
glBufferData (GL_ARRAY_BUFFER, sizeof(varray), varray, GL_STATIC_DRAW);
checkError ("initBuffer");
}
const GLchar *vertexShaderSource[] = {
"#version 140
",
"uniform mat4 fg_ProjectionMatrix;
",
"in vec4 fg_Color;
",
"in vec4 fg_Vertex;
",
"smooth out vec4 fg_SmoothColor;
",
"void main()
",
"{
",
" fg_SmoothColor = fg_Color;
",
" gl_Position = fg_ProjectionMatrix * fg_Vertex;
",
"}
"
};
const GLchar *fragmentShaderSource[] = {
"#version 140
",
"smooth in vec4 fg_SmoothColor;
",
"out vec4 fg_FragColor;
",
"void main(void)
",
"{
",
" fg_FragColor = fg_SmoothColor;
",
"}
"
};
void compileAndCheck(GLuint shader)
{
GLint status;
glCompileShader (shader);
glGetShaderiv (shader, GL_COMPILE_STATUS, &status);
if (status == GL_FALSE) {
GLint infoLogLength;
GLchar *infoLog;
glGetShaderiv (shader, GL_INFO_LOG_LENGTH, &infoLogLength);
infoLog = (GLchar*) malloc (infoLogLength);
glGetShaderInfoLog (shader, infoLogLength, NULL, infoLog);
fprintf (stderr, "compile log: %s
", infoLog);
free (infoLog);
}
}
GLuint compileShaderSource(GLenum type, GLsizei count, const GLchar **string)
{
GLuint shader = glCreateShader (type);
glShaderSource (shader, count, string, NULL);
compileAndCheck (shader);
return shader;
}
void linkAndCheck(GLuint program)
{
GLint status;
glLinkProgram (program);
glGetProgramiv (program, GL_LINK_STATUS, &status);
if (status == GL_FALSE) {
GLint infoLogLength;
GLchar *infoLog;
glGetProgramiv (program, GL_INFO_LOG_LENGTH, &infoLogLength);
infoLog = (GLchar*) malloc (infoLogLength);
glGetProgramInfoLog (program, infoLogLength, NULL, infoLog);
fprintf (stderr, "link log: %s
", infoLog);
free (infoLog);
}
}
GLuint createProgram(GLuint vertexShader, GLuint fragmentShader)
{
GLuint program = glCreateProgram ();
if (vertexShader != 0) {
glAttachShader (program, vertexShader);
}
if (fragmentShader != 0) {
glAttachShader (program, fragmentShader);
}
linkAndCheck (program);
return program;
}
GLuint fgProjectionMatrixIndex;
GLuint fgColorIndex;
GLuint fgVertexIndex;
void initShader(void)
{
const GLsizei vertexShaderLines = sizeof(vertexShaderSource) / sizeof(GLchar*);
GLuint vertexShader =
compileShaderSource (GL_VERTEX_SHADER, vertexShaderLines, vertexShaderSource);
const GLsizei fragmentShaderLines = sizeof(fragmentShaderSource) / sizeof(GLchar*);
GLuint fragmentShader =
compileShaderSource (GL_FRAGMENT_SHADER, fragmentShaderLines, fragmentShaderSource);
GLuint program = createProgram (vertexShader, fragmentShader);
glUseProgram (program);
fgProjectionMatrixIndex = glGetUniformLocation(program, "fg_ProjectionMatrix");
fgColorIndex = glGetAttribLocation(program, "fg_Color");
glEnableVertexAttribArray (fgColorIndex);
fgVertexIndex = glGetAttribLocation(program, "fg_Vertex");
glEnableVertexAttribArray (fgVertexIndex);
checkError ("initShader");
}
void initRendering(void)
{
glClearColor (0.0, 0.0, 0.0, 0.0);
checkError ("initRendering");
}
void init(void)
{
initBuffer ();
initShader ();
initRendering ();
}
void dumpInfo(void)
{
printf ("Vendor: %s
", glGetString (GL_VENDOR));
printf ("Renderer: %s
", glGetString (GL_RENDERER));
printf ("Version: %s
", glGetString (GL_VERSION));
printf ("GLSL: %s
", glGetString (GL_SHADING_LANGUAGE_VERSION));
checkError ("dumpInfo");
}
const GLvoid *bufferObjectPtr (GLsizei index)
{
return (const GLvoid *) (((char *) NULL) + index);
}
GLfloat projectionMatrix[16];
void triangle(void)
{
glUniformMatrix4fv (fgProjectionMatrixIndex, 1, GL_FALSE, projectionMatrix);
glBindBuffer (GL_ARRAY_BUFFER, vertexBufferName);
glVertexAttribPointer (fgColorIndex, numColorComponents, GL_FLOAT, GL_FALSE,
stride, bufferObjectPtr (0));
glVertexAttribPointer (fgVertexIndex, numVertexComponents, GL_FLOAT, GL_FALSE,
stride, bufferObjectPtr (sizeof(GLfloat) * numColorComponents));
glDrawArrays(GL_TRIANGLES, 0, numElements);
checkError ("triangle");
}
void display(void)
{
glClear (GL_COLOR_BUFFER_BIT);
triangle ();
glFlush ();
checkError ("display");
}
void loadOrthof(GLfloat *m, GLfloat l, GLfloat r, GLfloat b, GLfloat t,
GLfloat n, GLfloat f)
{
m[ 0] = 2.0f / (r - l);
m[ 1] = 0.0f;
m[ 2] = 0.0f;
m[ 3] = 0.0f;
m[ 4] = 0.0f;
m[ 5] = 2.0f / (t - b);
m[ 6] = 0.0f;
m[ 7] = 0.0f;
m[ 8] = 0.0f;
m[ 9] = 0.0f;
m[10] = -2.0f / (f - n);
m[11] = 0.0f;
m[12] = -(r + l) / (r - l);
m[13] = -(t + b) / (t - b);
m[14] = -(f + n) / (f - n);
m[15] = 1.0f;
}
void loadOrtho2Df(GLfloat *m, GLfloat l, GLfloat r, GLfloat b, GLfloat t)
{
loadOrthof (m, l, r, b, t, -1.0f, 1.0f);
}
void reshape (int w, int h)
{
glViewport (0, 0, (GLsizei) w, (GLsizei) h);
if (w <= h) {
loadOrtho2Df (projectionMatrix, 0.0f, 30.0f, 0.0f, 30.0f * (GLfloat) h/(GLfloat) w);
} else {
loadOrtho2Df (projectionMatrix, 0.0f, 30.0f * (GLfloat) w/(GLfloat) h, 0.0f, 30.0f);
}
checkError ("reshape");
}
void keyboard(unsigned char key, int x, int y)
{
switch (key) {
case 27:
exit(0);
break;
}
}
int main(int argc, char** argv)
{
glutInit(&argc, argv);
glutInitDisplayMode (GLUT_SINGLE | GLUT_RGB);
/* add command line argument "classic" for a pre-3.x context */
if ((argc != 2) || (strcmp (argv[1], "classic") != 0)) {
glutInitContextVersion (3, 1);
glutInitContextFlags (GLUT_FORWARD_COMPATIBLE | GLUT_DEBUG);
}
glutInitWindowSize (500, 500);
glutInitWindowPosition (100, 100);
glutCreateWindow (argv[0]);
dumpInfo ();
init ();
glutDisplayFunc(display);
glutReshapeFunc(reshape);
glutKeyboardFunc (keyboard);
glutMainLoop();
return 0;
}
One last comment on gl3 and linux, I try to keep the general gl3 files up to date with
wget http://www.opengl.org/registry/api/glext.h
wget http://www.opengl.org/registry/api/glxext.h
wget http://www.opengl.org/registry/api/gl3.h
sudo cp glext.h /usr/include/GL/
sudo cp glxext.h /usr/include/GL/
sudo cp gl3.h /usr/include/GL3/