Computer Graphics 2

Test review for Professor Thompson's Computer Graphics 2 class covering WebGL

Normals

a vector that is perpendicular to a surface at a specific point is also used to calculate lighting and shading.

Right-Hand Rule

determines direction in 3D space: curl your fingers in the rotation direction, and your thumb points along the axis.

Face Orientation

OpenGL uses winding order (clockwise or counterclockwise) to determine whether a face is front-facing or back-facing.

Counter Clockwise Vertices

create outward facing objects

Clockwise Vertices

Create inward facing objects

Culling

is the process of removing back-facing polygons to improve rendering performance.

Homogeneous Coordinates

represent 3D points using a fourth dimension. (x,y z) The last digit is 0 for vector and 1 for point.

Translation

moves an object to a new position in space without changing its orientation or size.

Rotation

turns an object around a specified axis by a given angle.

Scaling

changes the size of an object by enlarging or shrinking it along one or more axes.

Order of Transformations

Rotate, Scale Translate.

Model Matrix

defines the position, orientation, and scale of an object in the scene.

View Matrix

represents the camera's position and orientation in the scene.

Projection Matrix

determines how a 3D scene is projected onto a 2D screen.

Orthographic Projection

Keeps parallel lines unchanged and is used for technical drawings and objects don’t change size from distance.

Axonometric Projection

type of orthographic projection that displays 3D objects with uniform scaling from specific angles, like isometric views.

Oblique Projection

skews objects to show one face fully visible while others are angled.

Perspective Projection

shrinks objects as they move farther away to create a sense of depth.

Advantages of Orthographic Projections

They preserve dimensions and are ideal for technical drawings. However, they lack a sense of depth.

Advantages of Perspective Projections

Creates realistic depth and size relationships but distort parallel lines and dimensions.

lookAt Function

generates a view matrix to position and orient the camera toward a target point in 3D space. 3 inputs (eye,target, up)

Phong Lighting Model

calculates the angle between the viewing vector and the reflection vector to determine the specular component.

Modified Phong Lighting Model

Calculates the specular using the difference between the normal and the halfway vector for improved efficiency.

Specular Lighting

creates bright highlights where light reflects directly into the viewer’s eye.

Diffuse Lighting

scatters light evenly, simulating a matte surface's appearance.

Ambient Lighting

is uniform, simulating indirect light that illuminates all objects.

Texture Mapping

Texture mapping applies images to surfaces by mapping texture coordinates to object geometry.

Texture Mapping in the Pipeline

occurs during the fragment shading stage to determine pixel color.

Texture Wrapping

defines how textures repeat or stretch when mapped onto objects.

Halfway Vector

is the direction halfway between the light vector and the view vector, used to calculate the specular component.

gl.clearColor

Sets the background color

gl.clear

Clears the screen or buffers

gl.bindBuffer

Connects a buffer to WebGL

gl.bindTexture

Connects a texture to WebGL

gl.uniform1f

Sends a float value to the shader

gl.bufferData

Creates and fills a buffer

gl.bufferSubData

Creates and fills a buffer

gl.enable

Turns on a WebGL Feature

gl.cullFace

Chooses which poylgon side to ignore

gl_Postion

Sets the vertex postion in the shader

Eye

Where the camera is

Center

The point the camera is looking at

Up

The direction considered up

Whats the order of the view matrix?

eye, center, up each have three varibles xyz