1. Draw a Simple Object

2. Outline
Course Map
OpenGL Example
Functions’ Introduction

3. Fixed Pipeline Per-Vertex Operations Viewport culling & clipping
Vertex pipeline
Per-Vertex
Operations
Viewport culling
&
clipping
Primitive
assembly
Rasterize
Pixel pipeline
Fragment
Processing
Per Fragment
operations
Frame Buffer
operations
Framebuffer

4. Course Map Transformation & Lighting Viewport culling & clipping
We are here!
Vertex pipeline
Transformation
&
Lighting
Viewport culling
&
clipping
Primitive
assembly
Rasterize
Pixel pipeline
Texture
blending
Per Fragment
operations
Frame Buffer
operations
Framebuffer

5. Example 1/3

6. Example 2/3

7. Example 3/3

8. Result

9. Data Type

10. Clear the Buffers 1/2
void glClearColor(GLfloat red, GLfloat green, GLfloat blue, GLfloat alpha);
Set the current values for use in cleaning color buffers in RGBA mode
red, green, blue, alpha: Specify the red, green, blue, and alpha values used when the color buffers are cleared
void glClearDepth(GLdouble depth);
Set the current values for use in cleaning depth buffer
depth: Specifies the depth value used when the depth buffer is cleared

11. Clear the Buffers 2/2 void glClear(GLbitfield mask);
Clear the specified buffers to their current clearing values
mask: GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, GL_ACCUM_BUFFER_BIT, GL_STENCIL_BUFFER_BIT
EX: glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

12. Color Representation RGBA: red, green, blue, alpha
Each channel has intensity from 0.0~1.0
Values outside this interval will be clamp to 0.0 or 1.0
Alpha is used in blending and transparency
Specify a color:
void glColor{34}{sifd}[v](…);
EX: glColor3f(1.0f, 0.0f, 0.0f);

13. Points, Lines and Polygons 1/4
Describe points, lines, polygons
void glBegin(GLenum mode);
Marks the beginning of a vertex-data list
Vertex-data include vertex’s color, normal, position, etc.
mode: can be any of the values in next page
void glEnd();
Marks the end of a vertex-data list

14. Points, Lines and Polygons 2/4

15. Points, Lines and Polygons 3/4

16. Points, Lines and Polygons 4/4
Specifying the vertices
void glVertex{234}{sifd}[v](…)
Specifies a vertex for use in describing a geometric object
You have to set vertex’s attributes before glVertex
Ex: Use glColor before glVertex to set the vertex’s color
Can only effective between a glBegin() and glEnd() pair

17. Completion of Drawing void glFlush(); void glFinish();
Forces previously issued OpenGL commands to begin execution.
void glFinish();
Forces previous issued OpenGL commands to complete.
void glutSwapBuffers();
Swap front and back buffers.

18. Thanks for listening!
Any questions?