CG API, Graphics Pipeline

Tom Kelliher, CS 320

Jan. 26, 2001

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Assignment

Read Chapter 2.

From Last Time

CG applications, components, object and images, vision, pinhole and synthetic cameras.

Outline

1. CG APIs.

2. CG processing pipeline.

Coming Up

OpenGL programming.

CG API

1. Using the synthetic camera model, we must be able to specify:
   1. Objects.

      Different geometrical objects, characters, etc.

      Color, for 2-D objects.

   2. Viewer.

      Position, orientation, clipping volume, perspective.

   3. Light sources.

      Position, orientation, cone, brightness, color.

   4. Material properties.

      Specular, diffuse. Texture, etc.

2. Example:

   glColor3f(1.0, 0.0, 0.0);
   glBegin(GL_POLYGON);
      glVertex3f(0.0, 0.0, 0.0);
      glVertex3f(0.0, 1.0, 0.0);
      glVertex3f(0.0, 0.0, 1.0);
   glEnd();
   

3. Like Java, immediate mode graphics.

4. Like Java, settings modes.

5. Progress of rendering sophistication: wireframe, 2-D polygons, flat shading, smooth shading, texture maps, fog.

Graphics Pipeline

1. 3-D points represented by four element vectors.

2. Transformations applied by multiplications by series of matrices.

3. Stages:
   1. Transformer: rotate, shift, scale. Convert world coordinates to window coordinates.

   2. Clipper.

   3. Projector: 3-D to 2-D. Ortho, perspective views.

   4. Rasterizer.