OpenGL and Programmable Shaders

CS 381 Lecture, Dr. Lawlor

I've finally stripped down my set of OpenGL libraries to make a relatively simple example program. It's called glsl_bare (Zip, Tar-gzip). (UPDATED Friday 3 pm: it should actually build anywhere now, and has been verified on Windows and Linux. I provide a Visual C++ 2003 project file, Code::Blocks project file, and Linux/Mac OS X Makefile.)

C++ Libraries used with OpenGL

Name	Description	Reference	Header	Windows	Linux	Mac OS X
OpenGL	Basic rendering calls: triangles, vertices, textures, etc.	The OpenGL FAQ is a good place to start, or the Manual Pages. The OpenGL 1.4 Specification is unreadable legalese. The Red Book is dated but readable.	<GL/gl.h> (note captialization, Windows people!)	opengl32.lib (Usually have to add this to your project's linker properties...)	libGL.so	-framework OpenGL
GLUT	Create windows, set up buffers, handle keyboard and mouse.	The original GLUT API document is readable.	<GL/glut.h>	glut32.lib or freeglut.lib	libglut.so	-framework GLUT
GLEW	Dynamic interface to latest OpenGL routines. A must for programmable shaders on Windows!	GLEW makes OpenGL routines work as advertised. The only pure-GLEW routine is glewInit().	<GL/glew.h> (Include first; this replaces GL/gl.h!)	(I prefer it statically linked)
GLUI	Buttons, scrollbars, dropdown menus, and other widgets.	I've prepared some doxygen comments. There's also an older GLUI manual.	<GL/glui.h>	(I prefer it statically linked)
ogl	Orion's random crappy OpenGL utilities	Read the ogl/ header files.	"ogl/util.h", "ogl/main.h", ...	(I prefer it statically linked)

C++ Matrix and Vector Classes

I've posted two interesting header files as part of the glsl_bare example above:

    #include "osl/vec4.h"
    #include "osl/mat4.h"
    using namespace osl;

These contain an implementation of the GLSL "vec4" and "mat4" types in C++. You can now usually just copy-and-paste GLSL vector and matrix code into C++, and it should "just magically work". In particular, any legal GLSL vec4 or mat4 operation should be legal C++; but of course send me an email if you find a mismatch!

The command to upload a matrix into a GLSL program is glUniformMatrix4fv. Call it with an osl "mat4" like this:
    glUniformMatrix4fvARB(glGetUniformLocationARB(prog,"mF"),1,0,&mF[0][0]);

The "1" is because we've only got one matrix to upload. The "0" is because we don't need to transpose--mat4 is already column-major.