This is an Introduction to the OpenGL shaders. When you need high performance or customized features in your 3D program, these are the way to go.

1. SHADERS:
Releasing the power of the GPU
(and your creativity)

2. PART I:
THE SHADER CONCEPT

3. 3D Programming

4. Rasterization

5. THE BIRTH OF GPU SHADERS
1. No special hardware
2. Hardware acceleration
3. Programmable Hardware
4. Programmable Hardware Interface

6. Rasterization (GPU)

7. PART II:
THE OPENGL SHADER API

8. How do we make a program?
1. Enter some text in a file
2. Compile the file
3. Check for compilation errors
4. Link some compiled code
5. Check for linking errors
6. Run your program!

9. How do we make a program?
1. Enter somewin.cin a file
1. vim text
2.2.gcc –Wall thewin.c
Compile –c file
3. Check 3. echo $?
for compilation errors
4. gcc –Wall win.o iexplore.o
4. Link some compiled code
5. Check for linking errors
5. echo $?
6. Run your program!
6. ./a.out

10. How do we make a program?
1. Enter somewin.cin a file
1. 1. vim text
ShaderSource()
2.2.gcc –Wall thewin.c
2. CompileShader()
Compile –c file
3. Check 3. echo $?
3. COMPILE_STATUS
for compilation errors
4. 4. gcc –Wall win.o iexplore.o
4. Link some compiled code
AttachShader(); LinkProgram()
5. Check for linking errors
5. 5. echo $?
LINK_STATUS
6. 6. UseProgram()
Run your program!
6. ./a.out

11. • SHADER OBJECT • PROGRAM OBJECT
• glCreateShader • glCreateProgram
• glDeleteShader • glDeleteProgram
• glShaderSource • glAttachShader
• glCompileShader • glDetachShader
• glLinkProgram
• glIsShader • glUseProgram
• glGetShaderiv • glValidateProgram
• glGetShaderInfoLog
• glIsProgram
• glGetProgramiv
• glGetProgramInfoLog

12. #define BUFSZ 1024
#define SHADER_SOURCE = quot;void main (void) { gl_Position = ftransform (); }quot;
GLuint vert;
GLint stat;
char buf[BUFSZ];
vert = glCreateShader (GL_VERTEX_SHADER);
glShaderSource (vert, 1, SHADER_SOURCE, NULL);
glCompileShader (vert);
glGetShaderInfoLog (vert, BUFSZ, NULL, buf);
printf (quot;log: %snquot;, buf);
glGetShaderiv (vert, GL_COMPILE_STATUS, &stat);
printf (quot;compile %snquot;, (stat == GL_TRUE)? quot;okquot;: quot;failedquot;);
glDeleteShader (vert);

13. #define BUFSZ 1024
GLuint vert, frag, prog;
GLint stat;
char buf[BUFSZ];
vert = my_load_shader (quot;vertex.glslquot;);
frag = my_load_shader (quot;fragment.glslquot;);
prog = glCreateProgram ();
glAttachShader (prog, vert);
glAttachShader (prog, frag);
glLinkProgram (prog);
glGetProgramInfoLog (prog, BUFSZ, NULL, buf);
printf (quot;log: %snquot;, buf);
glGetProgramiv (program, GL_LINK_STATUS, &stat);
printf (quot;link %snquot;, (stat == GL_TRUE)? quot;okquot;: quot;failedquot;);

14. PART III:
GLSL PROGRAMMING

17. Vertex Attributes Uniforms
glVertexAttrib* glGetUniformLocation
glBindAttribLocation glUniform*

18. GLuint prog; GLint texLoc, timeLoc; GLfloat time;
#define WEIGHT_INDEX 1
prog = my_load_prog ();
texLoc = glGetUniformLocation (prog, quot;texquot;); if (texLoc == -1) my_panic ();
timeLoc = glGetUniformLocation (prog, quot;timequot;); if (timeLoc == -1) my_panic ();
glBindAttribLocation (prog, WEIGHT_INDEX, quot;weightquot;);
glUseProgram (prog);
glUniform1i (texLoc, 0); // USE TEXTURE UNIT 0
while (not_stop) {
time = my_time_update ();
glUniform1f (timeLoc, time);
my_render_func ();
}
glUseProgram (0);

19. LET'S WRITE SHADERS!

24. THANK YOU!
and enjoy your CG practical
tom@mimicmedia.nl