1. Review of OpenGL Basics
Chap. 1 of Orange Book

2. Contents OpenGL History Execution model Framebuffer State
Processing Pipeline
Drawing geometry
Drawing images
Coordinate transform
Texture map

3. History of OpenGL Revisions
Version 1.0 (1992): initial release
Version 1.1 (1997): vertex arrays and texture objects.
Version 1.2 (1998): 3D textures and an optional set of imaging functionality.
Version 1.3 (2001): cube map textures, compressed textures, multitextures, …
Version 1.4 (2002): automatic mipmap generation, additional blending functions, internal texture formats for storing depth values for use in shadow computations, support for drawing multiple vertex arrays with a single command, more control over point rasterization, control over stencil wrapping behavior, and various additions to texturing capabilities.
Version 1.5 (2003): vertex buffer objects, shadow comparison functions, occlusion queries, and non-power-of-2 textures.

4. OpenGL 2.0 (Sept.2004)
opened up the processing pipeline for user control by providing programmability for both vertex processing and fragment processing
OpenGL 2.0 is completely backward compatible with OpenGL 1.5
Other features: multiple render targets (rendering to multiple buffers simultaneously), non-power-of-2 textures, point sprites, and separate stencil functionality for front- and back-facing surfaces.

5. Execution Model: client-server
An application program (the client) issues OpenGL commands that are interpreted and processed by an OpenGL implementation (the server).
The application program and the OpenGL implementation can execute on a single computer or on two different computers.
Some OpenGL state is stored in the address space of the client, but the majority of it is stored in the address space of the server.
OpenGL commands are always processed in the order in which they are received by the server

6. State Machine
OpenGL was designed as a state machine. Cumulatively, the state settings define the behavior of the OpenGL rendering pipeline and the way in which primitives are transformed into pixels on the display device.
OpenGL state is collected into a data structure called a graphics context. Window-system-specific functions create and delete graphics contexts.
Quite a few server-side state values in OpenGL have just two states: on or off, controlled by glEnable and glDisable. Client-side state values (such as pointers that define vertex arrays) are controlled by glEnableClientState and glDisableClientState.
OpenGL maintains a server-side stack for pushing and popping any or all of the defined state values. This stack can be manipulated with glPushAttrib and glPopAttrib. Similarly, client state can be manipulated on a second stack with glPushClientAttrib and glPopClientAttrib.
glGet is a generic function that can query many of the components of a graphics context.

7. Fixed Functionality of OpenGL

8. Drawing Geometry Sending geometry Per-vertex operations: T&L
T&L : transformation and lighting
Sending geometry
vertex-at-a-time
Vertex array
Display list
new in 1.5: VBO, server-side vertex array
Per-vertex operations: T&L
vertex positions are transformed by the modelview and projection matrices
normals are transformed by the inverse transpose of the upper leftmost 3 x 3 matrix taken from the modelview matrix
texture coordinates are transformed by the texture matrices
lighting calculations are applied to modify the base color
texture coordinates may be automatically generated
color material state is applied
point sizes are computed [how]

9. Drawing Geometry Primitive assembly Primitive processing Rasterization
vertex data is collected into complete primitives
Primitive processing
clipping, culling, perspective-divide
Rasterization
A fragment comprises a window coordinate, depth, and other associated attributes such as color, texture coordinates, and so on.
Size,width,stipple, …
Fragment processing
Texture mapping, fog
Per-fragment operations
Scissor, depth, stencil, …
Framebuffer operations
Clear, masking, buffer

10. Images – (known as)pixel rectangles
Pixel unpacking
Data of pixel rectangles transferred from memory to OpenGL
Pixel transfer
glDrawPixels, …
glReadPixels; glCopyPixels
Rasterize and placement
glRasterPos; glPixelZoom
Read control
glReadBuffer

11. Coordinate Transformation
Light positions are stored within OpenGL as eye coordinate
light positions and surface normals must be in the same coordinate system.
glLoadIdentity; glMultMatrix;
gluLookAt
glTranslate; glScale; glRotate
glPushMatrix; …
glOrtho; gluPerspective;
glViewport

12. Texture Mapping Texture Mapping = Texture access + texture application
Texture unit:
the underlying piece of graphics hardware that performs the various texturing operations.
A texture unit can be enabled for 1D, 2D, 3D, or cube map texturing
Texture object:
a name and a texture target (1D,2D,3D,cubemap)
associated to a texture unit
Texture parameters are then assigned (filters, wrap, …)
Texture environment and texgen are not stored in texture objects

13. Texture Mapping Texture environment: Multitexture TexGen
the manner in which a texture value is applied to a graphics primitive (replace, modulate, …)
Multitexture
serially connect texture units
glActiveTexture, glMultiTexCoord, …
TexGen
Procedurally generate texture coordinates

14. Excursions Vertex array New OpenGL features Reflection models
Explanation, spec, example, tutorial, …
sought
Vertex array
What’s the significance of “client-side”? glEnableClientState
[how they are used to specify geometry]
[vertex array object: server-side vertex array]
New OpenGL features
Secondary color
Compressed texture
Reflection models
Blinn-Phong: what’s the halfVector in a light?
Hemispheric lighting
Cook-Torrance, Oren-Nayar, Ward, Ashikhmin-Shirley
High dynamic range lighting