Computer Graphics involves technology to access. The Process transforms and presents information in a visual form. The role of computer graphics insensible.

Computer Graphics involves technology to access. The Process transforms and presents information in a visual form. The role of computer graphics insensible. In today life, computer graphics has now become a common element in user interfaces, T.V. commercial motion pictures.

Computer Graphics is the creation of pictures with the help of a computer. The end product of the computer graphics is a picture it may be a business graph, drawing, and engineering.

In computer graphics, two or three-dimensional pictures can be created that are used for research. Many hardware devices algorithm has been developing for improving the speed of picture generation with the passes of time. It includes the creation storage of models and image of objects. These models for various fields like engineering, mathematical and so on.

1. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Chapter 7:
Graphical Primitives

2. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
This Chapter: we will learn
Types of primitives:
Points, Lines, and Triangles
Attributes of primitives:
Per-primitive and Per-Vertex attributes
E.g., colors, size, style, etc.
Programming with primitives
Abstraction + integration into UWBGL

3. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Point Primitives
Important because of:
Particles! –approximation
fire, water, explosions
Attributes:
Color, size, and
texture coordinates
Drawing commands:
DrawPoint
DrawPointList
Efficiency! Particles are lots of points

4. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Line Primitives
Important for:
Hairs, rains, etc.
Types:
One Line Segment
Line Segments or Line Lists
Collection of lines (not connected)
Line Strips or Polylines
Collection of connected lines
Line lists/strips
Efficient to specify large number

5. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Line: Attributes
Per-Vertex Attributes
Color
Gouraud Shading: linearly change colors from one vertex
to the next
Texture Coordinate
Normal Vector
Important for shading hair/rain
Per-Primitive Attributes
Material properties
Line Style/Width

6. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Triangle Primitive
Only drawing primitive
with area.
Geometries/objects
in most graphics applications are
approximated with triangles.

7. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Types of Triangles
Triangle (Lists)
Individual vertices
Triangle Fan
n+2 vertices specify n
connected triangles
Triangle Strip
n+2 vertices specify n
connected triangles

8. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Triangle: Attributes
Per-Vertex attribute
similar as per-vertex attribute of lines:
Color, normal, texture coordinates
Per-Edge attributes
Similar to per-line attributes:
Width, style, etc.
Per Triangle attribute
Material properties
Fill style: e.g., wire frame

9. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Color:
Usually expressed as:
(Red, Green, Blue) or (r, g, b)
Usually:
Normalized float: 0.0 ≤ r,g,b ≥1.0
Integer: 0.0 ≤ r,g,b ≥255
255: 8-bit per channel ( )

10. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib4: Geometries
Common Files/
DrawHelper/
API independent drawing support
Geoms/
Geometries (attributes + drawing)
E.g., color, shadeMode, FillMode, etc.
D3D Files/
D3D_DrawHelper
D3D specific drawing support
D3D_GraphicsSystem/
D3D API support (GHC, RC, and swap chain)
D3D_WindowHandler
D3D View/Controller pair support

11. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib4: New classes

12. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
DrawHelper:
Interface for drawing

13. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
D3DDrawHelper: class + attributes setting

14. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
D3DDrawHelper: Draw functions

15. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Geometry class: Point

16. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tutorial 7.1: Drawing Geometries

17. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tut 7.1: Model Implementation

18. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tut 7.1: DrawAndMouseHandler

19. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tut 7.1: The Dialog Window

20. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib5: Primitive Hierarchy

21. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib5: Primitive Hierarchy

22. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWB_Primitive base class

23. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWB_PrimitivePoint class

24. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWB_PrimitiveLine class

25. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWB_PrimitiveCircle class

26. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tutorial 7.2:

27. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tut 7.2: DrawAndMouseHandler

28. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Primitive: Collisions
Attributes of primitive:
Appearance (color) vs. Physical (velocity)
Graphics: mainly concern with
appearance
Learn some physical attributes
Collision: mathematic intersection

29. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Collision with intersection
With n different primitive types
Need O(n
2
) different intersection routines!
E.g., line, circle, point: needs
Line-Line, Line-Circle, Line-Point, Circle-Circle,
Circle-Point, Point-Point
In general: n+(n-1)+(n-2)
Intersection Math is tedious
Complex Invocation
logic to determine which of the routines to invoke

30. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Collision with: Bounding volumes
Bounds primitive with
simple volumes
E.g. x/y/z bounds
E.g., circle/spheres
Collide with the
bounding volumes
instead!

31. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Bounding Volume considerations
Simplicity in math
circle/sphere and axes aligned bounding boxes
Tightness in bound
Void space
Approximation
False collision and
Failed detection
Colliding position
On bounding circle is different from on object

32. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib6: Bounding Volume
Intersects() collide two volumes
Returns True/False (no colliding position)
Add()
Inserts and expends the volume

33. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWBGL_Lib6: BoundingBox Class

34. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
UWB_BoundingBox

35. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Primitive: CollisionResponse
Primitive class:
has a bounding volume
CollisionResponse(): collision detected
other_location –location of other primitive
Change primitive behavior accordingly
Knows how to draw bounding volume

36. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Using BoundingVolume
Three steps:
1. Get the volume from each primitives
2. Collide the volumes
3. If volumes collide
Each primitive must response: CollisionResponse()

37. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Default collision response …
Change velocity to repulse away
Looks like bouncing away
Very rough approximation of
elastic collision

38. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tutorial 7.3: Collision

39. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Lib7: Collection of Primitives
PrimitiveList class Subclass of Primitive
Behave just like a primitive

40. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Lib7: PrimitiveList Class

41. Essentials of Interactive Computer Graphics: Concepts and Implementation K. Sung, P. Shirley, S. Baer
Chapter 7
Tutorial 7.4: Many primitives