Computer-Graphics-Handout2

Window

Graphical interface element that displays the application’s content.

Startup Stage

Initial phase where objects are created, values are set, and files are loaded.

Main Loop

Continuous cycle while the program is running, consisting of:

Process Input

Detects user actions (keyboard/mouse).

Update

Changes object values and game variables.

Render

Draws/creates graphics for display.

Shutdown Stage

Final phase, stops user input processing and closes application windows.

Pygame

A Python library used for creating video games and graphics applications.

pygame.display.set_mode()

Function to create a window; requires width and height (e.g., (500, 500)).

Point

The most basic graphical element; a single location in space.

Vertex Shader

A program that runs once per vertex to compute its position in 3D space.

gl_Position

A built-in GLSL variable storing the current vertex position.

GLSL (OpenGL Shading Language)

Shader programming language used in OpenGL.

main() function (in GLSL)

Required function in every shader; entry point of shader code.

Vector Types (vec2, vec3, vec4)

GLSL data types for storing 2D, 3D, and 4D values (e.g., position, color).

w (4th component of vec4)

Controls clipping of vertex positions in 3D space, default is 1.0.

glBegin() & glEnd()

Functions that define the start and end of specifying vertices for a shape.

glVertex3f(x, y, z)

Specifies the position of a vertex in 3D space using float values.

Primitive

A basic shape in OpenGL (points, lines, triangles).

Primitive Assembly

Process of grouping vertices into shapes (e.g., triangles, strips, fans).

Uniform Variables

Global shader variables with constant values while drawing a shape (e.g., shared color, translation).

uniform (type qualifier)

Declares a variable in GLSL as a uniform variable.

glGetUniformLocation(programRef, variableName)

Function that retrieves the memory reference for a uniform variable inside a shader program.

Return value -1

Indicates the uniform variable does not exist or is not used in the shader.

Event

An action detected by the system (e.g., key pressed, mouse moved).

Keydown Event

Triggered when a key is pressed.

Keyup Event

Triggered when a key is released.

Discrete Event

Happens only once at a specific moment (e.g., pressing a key).

Continuous Event

Persists as long as the action is maintained (e.g., holding down a key to move a character).

pygame.KEYDOWN / pygame.KEYUP

Constants for detecting key press and release events.

pygame.K_w, pygame.K_a, pygame.K_s, pygame.K_d

Constants for detecting WASD key presses (used in movement controls).