CHAPTER 1:INTRODUCTION TO INTERACTIVE

COMPUTER GRAPHICS

1.1 Brief History of Computer Graphics:

o Evolution from early raster displays to modern interactive 3D environments.
o Development of graphic hardware and software, including frame buffers,
GPUs, and real-time rendering engines.

1.2. 3D Graphics Techniques and Terminology:

 Rendering: Process of generating an image from a 3D model.
 Modeling: Creation of 3D objects using polygons, curves, or splines.
 Shading: Techniques to simulate light interactions on surfaces.
 Texturing: Application of images to 3D surfaces for added detail.
 Transformation: Operations like scaling, rotation, and translation.
 View Frustum: 3D volume that defines what is visible in a scene.
 Clipping: Removing parts of objects outside the view frustum.
 Z-buffering: Technique to manage depth in a scene for proper layering.

1.3. Common Uses of Computer Graphics

 Entertainment:
 Video games
 Movies and animation
 Virtual reality (VR) and augmented reality (AR)
 Design and Manufacturing:
 Computer-aided design (CAD)
 Product visualization
 Simulation and prototyping
 Education and Training:
  Interactive learning tools
 Medical simulations
 Flight simulators
 Science and Research:
 Data visualization
 Scientific simulations
 Medical imaging
 Business and Marketing:
 Presentation graphics
 Advertising and branding
 User interface design

1.4. Application Areas

 Gaming:
 Creating realistic and immersive game environments
 Developing character models and animations
 Designing game interfaces and user experiences
 Film and Animation:
 Creating special effects and visual elements
 Animating characters and objects
 Designing virtual sets and environments
 Architecture and Engineering:
 Designing buildings and structures
 Creating architectural visualizations
 Simulating building performance and energy efficiency
 Medical Field:
 Developing surgical simulators
 Analyzing medical images
 Creating 3D models of anatomical structures
 Automotive Industry:
  Designing and testing car models
 Creating virtual driving simulations
 Developing advanced driver assistance systems (ADAS)
 Advertising and Marketing:
 Creating visually appealing advertisements
 Designing product packaging
 Developing interactive marketing campaigns
 Education and Training:
 Creating interactive learning materials
 Simulating real-world scenarios
 Providing hands-on training experiences
CHAPTER 2: GRAPHICS HARDWARE (2HR)

Graphics Hardware
Graphics hardware refers to the physical components of a computer
system that are responsible for processing and displaying visual
information. These components work together to create the images,
animations, and graphics that we see on our screens.
Some of the key components of graphics hardware include:

 Graphics Processing Unit (GPU): This is a specialized processor

designed to handle the computationally intensive tasks involved in
creating graphics, such as rendering, shading, and texturing.
 Video Memory (VRAM): This is a type of memory that is dedicated to
storing graphics data.
 Display Adapter: This is a circuit board that connects the GPU to the
display device (e.g., monitor, TV).
 Display Device: This is the physical device (e.g., monitor, TV) that
displays the images created by the graphics hardware.
Graphics hardware is essential for a wide range of applications,
including gaming, video editing, 3D modeling, and scientific
visualization.

2.1. Raster Display Systems

 Rasterization: The process of converting vector graphics (lines, curves)
into a pixel-based image (raster image).
 Pixels: Smallest units of a display, organized in a grid to form images.
 Frame Buffer: Memory area that holds pixel data for the image to be
displayed.
  CRT vs. LCD: Early raster displays used cathode ray tubes (CRTs), while
modern systems typically use liquid crystal displays (LCDs).
 Color Depth: Number of bits per pixel, determining the range of colors
(e.g., 24-bit for true color).
 Display Controller: A circuit that manages the display process,
including synchronizing the electron beam (CRT) or LCD panel with the
frame buffer and controlling the intensity of the beam or pixels.

2.2. Introduction to the 3D Graphics Pipeline

 Stages of the Pipeline:
 Modeling/Transformation: Converting 3D objects into appropriate
forms for rendering.
 Clipping and Viewport Transformation: Removing parts of objects
outside the view and mapping 3D coordinates to 2D screen coordinates.
 Lighting/Shading: Applying light sources to create realistic
appearances.
 Rasterization: Converting the 3D scene into pixels.
 Fragment Processing: Calculating color, depth, and texture for
individual pixels.
 Final Image Output: Composing the final image in the frame buffer for
display.
 Key Components:
 Graphics Processing Unit (GPU): A specialized processor designed to
handle the computationally intensive tasks of the 3D graphics pipeline,
such as rasterization, shading, and texturing.
 Graphics API: A software interface that provides a standardized way for
applications to interact with graphics hardware. Examples include
OpenGL, Direct3D, and Vulkan. These concepts provide an
understanding of the hardware and process that power graphical output,
including the role of rasterization in creating images, the stages involved
 in the 3D graphics pipeline, and the key components like GPUs and
graphics APIs.

2.3. The Z-Buffer for Hidden Surface Removal

Z-Buffering (Depth Buffering): A technique used to determine which
objects, or parts of objects, are visible in a scene by comparing depth values
(Z-values) at each pixel.

Key Concepts:
 Z-Value: Represents the depth of a pixel (distance from the camera).
 Frame Buffer: Stores the color of each pixel, while the Z-buffer stores
the depth information.
 Comparison: For each pixel, the system compares the Z-value of new
objects with the current Z-value in the buffer.
 Updating: If the new object’s Z-value is closer (smaller), the color and
depth values are updated in the frame buffer and Z-buffer, respectively.
 Hidden Surface Removal: Ensures that only the nearest surfaces
(those visible from the camera) are rendered, while others behind them
are discarded.
Process:
 Initialization: The Z-buffer is initialized with a large value (e.g., infinity)
to represent the maximum depth.
 Rendering: As each pixel is rendered, its depth value (distance from the
camera) is compared to the corresponding value in the Z-buffer.
o If the new depth value is less than the existing value, the pixel's color is
updated, and the Z-buffer value is overwritten.
o If the new depth value is greater than or equal to the existing value, the
pixel is discarded (hidden).
 Benefits:
 Efficient hidden surface removal: Quickly determines which parts of a
scene are obscured by others.
 Accurate depth testing: Ensures that objects closer to the camera
appear in front of objects farther away.
 Transparency support: Can be used in conjunction with alpha blending
to create transparent objects.
This technique is fundamental for producing accurate depth perception in
3D scenes and helps achieve realism in rendering.
 CHAPTER3: INTRODUCTION TO THE
RENDERING PROCESS WITH OPENGL

3. Computer Graphics Fundamentals

3.1. The Role of OpenGL in the Reference Model

 OpenGL: A cross-platform API used for rendering 2D and 3D vector
graphics.
 Reference Model Role:
o Acts as an interface between software and graphics hardware.
o Provides a standardized set of functions for creating and manipulating
graphics.
o Utilizes the graphics pipeline to manage tasks such as transformations,
lighting, and shading.
o OpenGL abstracts low-level hardware details, allowing developers to focus
on high-level graphical design.

3.2. Coordinate Systems

 Object Coordinate System: Local coordinate space where objects are
defined.
 World Coordinate System: Global space where all objects are placed in
a 3D scene.
 Camera/View Coordinate System: Defined relative to the camera's
position and orientation, used to transform world coordinates for
viewing.
 Clip Coordinate System: After applying projection, used for clipping
objects outside the view frustum.
  Screen Coordinate System: Final 2D coordinates where the scene is
rendered as pixels on the display.

3.3. Viewing Using a Synthetic Camera

 Synthetic Camera Model: Simulates how a real-world camera views a
scene.
 Projection: Converts 3D objects into 2D images using either perspective
projection (realistic) or orthographic projection (parallel).
 View Volume (Frustum): The 3D region visible to the camera, defined
by field of view and clipping planes.
 Look-at Matrix: Determines camera position, target (where the camera
is looking), and up direction.
 Transformation: Objects are transformed from world space to
camera/view space for rendering.

3.4. Output Primitives and Attributes

 Output Primitives:
 Points: Simplest primitive representing a position in space.
 Lines: Defined by two points, used to form wireframes.
 Polygons: Filled shapes (usually triangles) that form the surface of 3D
models.
 Curves and Surfaces: Parametric forms like Bézier curves or NURBS
for smooth shapes.
 Attributes:
 Color: Defines the color of a primitive (RGB values).
 Line Style: Determines the appearance of lines (solid, dashed).
 Fill Style: Specifies how polygons are filled (solid or patterned).
 Shading: Controls how light interacts with primitives, affecting realism
(e.g., flat shading, Gouraud shading, Phong shading).
These sections describe essential elements for understanding how 3D
objects are created, manipulated, and rendered in computer graphics.

Color in Computer Graphics: TGB and CIE

Color in Computer Graphics
Color is a fundamental aspect of computer graphics, used to create visually
appealing and informative images. It's essential to understand how color is
represented and manipulated in digital systems.

TGB Color Model

The TGB (Transparent, Green, Blue) color model is a variation of the RGB
color model, commonly used in computer graphics. It adds a transparency
channel (T) to the standard RGB model, allowing for the creation of
transparent or semi-transparent colors.

 T (Transparency): Controls the opacity of the color. A value of 0 means

fully transparent, while a value of 1 means fully opaque.
 G (Green): Controls the intensity of the green component.
 B (Blue): Controls the intensity of the blue component.
CIE Color Space
The CIE (Commission Internationale de l'Éclairage) color space is a
standardized system for defining and measuring color. It provides a way to
represent all perceivable colors, including those that cannot be reproduced
by standard display devices.

CIE XYZ Color Space: A device-independent color space that defines

colors in terms of three primary colors: X, Y, and Z.
 CIE Lab Color Space:* A perceptually uniform color space that is more
suitable for human color perception. It consists of three components:
 L:* Luminance or lightness
 a:* Red-green color component
 b:* Yellow-blue color component
Color in Computer Graphics Applications
Color is used in various computer graphics applications, including:

 Image and Video Processing: Color manipulation techniques are used to

enhance image quality, correct color distortions, and create special effects.
 3D Graphics: Color is used to define the appearance of objects, materials,
and lighting conditions in 3D scenes.
 User Interface Design: Color is used to create visually appealing and
intuitive user interfaces.
 Data Visualization: Color is used to encode information in charts, graphs,
and maps.

Key Considerations for Color in Computer Graphics:

 Color Gamut: The range of colors that a display device can reproduce.
 Color Perception: How humans perceive color, which is influenced by
factors like lighting conditions and individual variations.
 Color Management: The process of ensuring accurate color reproduction
across different devices and workflows.
By understanding the TGB color model, the CIE color space, and the
principles of color perception, you can effectively use color to create
visually compelling and informative graphics.

Image Formats: GIF, JPG, and PNG and others

These three image formats are commonly used on the web and in various
digital applications. Each format has its own strengths and weaknesses,
1

making them suitable for different types of images.

 1. GIF (Graphics Interchange Format) 3

 Key characteristics:
 Supports animation 4

 Lossless compression (maintains image quality) 5

 Limited color palette (256 colors) 6

 Best suited for:

 Simple images with solid colors 7

 Small animations and icons 8

 Logos and brand graphics

2. JPG (Joint Photographic Experts Group) 9

 Key characteristics:
 Lossy compression (reduces file size by discarding some image data) 10

 Supports a wide range of colors 11

 Best suited for photographs and images with continuous tones and
gradients 12

 Best suited for:

 Digital photographs 13

 Web graphics (especially for large images)

 Images with subtle color variations

3. PNG (Portable Network Graphics) 14

 Key characteristics:
 Lossless compression 15

 Supports transparency 16

 Supports a wide range of colors 17

 Best suited for:

 Images with sharp edges and text 18

 Screenshots

 Web graphics that require transparency or high-quality color

reproduction 19

4. BMP (Bitmap)
 Key characteristics:
 Lossless compression

 Supports a wide range of colors

 Large file sizes

 Best suited for:

 High-quality images that need to be edited

 Windows-based applications

5. TIFF (Tagged Image File Format)

 Key characteristics:
 Lossless or lossy compression

 Supports a wide range of colors

 Supports multiple layers and channels

 Best suited for:

 High-resolution images

 Professional printing

 Image archiving

6. WebP
 Key characteristics:
 Lossless or lossy compression

 Supports transparency

 Smaller file sizes than JPG and PNG

 Best suited for:

 Web graphics and mobile applications

Choosing the Right Format

When choosing an image format, consider the following factors:

 Image quality: If image qu ality is paramount, PNG or GIF is a better

choice.
 File size: For smaller file sizes, JPG is often preferred. 20
 Color depth: If you need a wide range of colors, JPG or PNG is suitable.
 Transparency: PNG is the best choice for images with transparency. 21

 Animation: GIF is the only format that supports animation.

By understanding the strengths and weaknesses of these formats, you can
choose the

CHAPTER 4: GEOMETRY AND LINE GENERATION (5HR)

4.1. Point and Lines, Bresenham's Algorithm, Generating Circles
Points and Lines:
 Points: The smallest addressable element of a display device, represented
by a single pixel.
 Lines: A series of connected points, forming a straight path between two
endpoints.
 Line Drawing Algorithms: Algorithms to efficiently plot lines on a raster
display.
 Bresenham's Line Algorithm: A popular algorithm for drawing lines,
known for its efficiency and simplicity. It iteratively determines which pixel
to plot based on the error term between the ideal line and the discrete pixel
locations.
Bresenham's Algorithm for Generating Circles:
 Principle: Similar to the line algorithm, it uses a decision parameter to
determine the next pixel to be plotted.
 Steps:
1. Initialization:
 Set initial values for x, y, and the decision parameter d.

2. Plotting the First Quadrant:

 Plot the initial point (x, y).

 Calculate the decision parameter d.

3. Iterative Plotting:
 If d < 0, the next pixel is (x+1, y). Update d accordingly.

 If d >= 0, the next pixel is (x+1, y-1). Update d accordingly.

4. Symmetry:
 Utilize symmetry to plot points in the other seven octants of the circle.
 Advantages:
o Efficient and accurate.

o Uses only integer arithmetic, making it suitable for hardware

implementation.

4.2. Plotting General Curves

 Parametric Equations: Curves can be defined using parametric equations,
where x and y are functions of a parameter t.
 Polynomial Interpolation: Fitting a polynomial curve to a set of given
points.
 Spline Curves: Smooth curves defined by a set of control points.
o Bezier Curves: Smooth curves defined by control points that influence the
curve's shape.
o B-Spline Curves: More flexible curves than Bezier curves, allowing for
local control.
4.3. Line Thickness
 Simple Approach: Plotting multiple lines parallel to the desired line.
 Anti-Aliasing: Smoothing the edges of lines to reduce the "jagged"
appearance.
o Pixel Weighting: Assigning different weights to pixels based on their
proximity to the ideal line.
o Subpixel Rendering: Rendering at a higher resolution and then
downsampling to the display resolution.
Additional Considerations:
 Clipping: Determining which parts of a line or curve are visible within a
specified window.
 Transformations: Applying transformations like rotation, scaling, and
translation to objects.
 Shading and Lighting: Creating realistic images by simulating the
interaction of light with surfaces.
Visual Resources:
 Bresenham's Line Algorithm:
 Bresenham's Circle Algorithm:
 Bezier Curve:
 Anti-Aliasing:
4.4. Line Style
Line style refers to the visual characteristics of a line, such as its width,
color, and pattern.

 Line Width: Determines the thickness of the line.

 Line Color: Specifies the color of the line.
 Line Pattern: Defines the pattern of dashes and gaps in the line.
4.5. Polygons
A polygon is a closed shape formed by connecting a sequence of points.

 Polygon Representation: Polygons can be represented as a sequence of

vertices or as a set of edges.
 Polygon Filling: The process of filling the interior of a polygon with a color
or pattern.
 Polygon Clipping: The process of determining which parts of a polygon
are visible within a specified window.
4.6. Filling
 Filling is the process of coloring or patterning the interior of a shape.

 Scan-Line Algorithm: A common algorithm for filling polygons, which

scans each horizontal line of the polygon and determines which pixels to fill.
 Flood-Fill Algorithm: A recursive algorithm that starts from a seed pixel
and fills adjacent pixels with the same color until a boundary is reached.
4.7. Text and Characters
Text and characters are essential for displaying information on a computer
screen.

 Font: A set of characters with a specific design.

 Font Size: Determines the size of the characters.
 Font Style: Specifies the style of the characters, such as bold, italic, or
underline.
 Text Rendering: The process of converting text into pixels on a display.
 Text Alignment: Specifies how text is aligned within a given area, such as
left, right, center, or justified.
Additional Considerations:
 Rasterization: The process of converting vector graphics into pixel-based
images.
 Anti-Aliasing: A technique used to smooth the edges of lines and curves to
reduce aliasing artifacts.
 Texture Mapping: Applying textures to surfaces to add detail and realism.
 Shading and Lighting: Simulating the interaction of light with surfaces to
create realistic images.
By understanding these fundamental concepts, you can create a wide range
of graphics, from simple line drawings to complex 3D scenes. Would you
like to delve deeper into any specific topic or see code examples for these
concepts?