PRELIM | Introduction to Computer Graphics | COMGRAPH

Computer Graphics

This term describes the use of computers to create and manipulate images.

Modeling, Rendering, and Animation

Major areas of computer graphics: M R A

Modeling

deals with the mathematical specification of shape and appearance properties in a way that can be stored on the computer.

Rendering

deals with the creation of shaded images from 3D computer models.

Animation

a technique to create an illusion of motion through a sequence of images.

Raster

Rendering a scene produces a ________.

Raster

It is an array of pixels (picture elements) displayed on a screen, arranged in a grid with two (2) dimensions.

Pixel

It means picture elements

Pixel

It specifies colors using triples of floating-point numbers between 0 and 1, which represent the amount of red, green, and blue light existing in a color;

0

This value indicates that no amount of that color exists

1

This represents that color is displayed at full intensity.

resolution and precision

The quality of an image depends partly on its ___________ and __________.

Resolution

It is the number of pixels in the raster

Precision

It is the number of bits used for each pixel.

Buffer (or data buffer, or buffer memory)

It is a part of a computer's memory that serves as temporary storage for data while being moved from one location to another.

Data Buffer or Buffer Memory

Buffer can also be called _________ or __________.

Pixel data

This data is stored in a region of memory called the framebuffer.

Framebuffer

Pixel data is stored in a region of memory called the ____________.

Framebuffer

It may contain multiple buffers that store different types of data for each pixel.

Color Buffer

The frame buffer needs this to store RGB values.

Depth Buffer

When rendering a 3D scene, the framebuffer must also contain a _______ __________.

Depth Buffer

This stores distances from points on scene objects to the virtual camera.

Depth values

It determines whether the object’s points are in front of or behind other objects (from the camera’s perspective). Thus, these values can also determine whether the points on each object will be visible when the scene is rendered.

Stencil Buffer

which may be used to store values used in generating advanced effects, such as shadows, reflections, or portal rendering.

Animations

It consists of a sequence of images quickly displayed.

Frame

Each of the images that is displayed is called a ________.

Frames Per Second (FPS)

The speed or rate at which these images appear is called the frame rate and is measured in ________ ___ _________.

Graphics Processing Unit (GPU)

It features a highly parallel structure that makes it more efficient than CPUs for rendering computer graphics.

Shaders

Programs run by GPUs are called. These are used to perform many different computations required in the rendering process.

Application Programming Interface (API)

Shader programming languages implement this which defines a set of commands, functions, and protocols that can be used in interacting with an external system such as the GPU.

DirectX API & High-Level Shading Language (HLSL)

used on Microsoft platforms, including the Xbox game console

Metal API & Metal Shading Language

runs on modern Mac computers, iPhones, and iPads

OpenGL (Open Graphics Library) API & OpenGL Shading Language (GLSL)

a cross-platform library. It is the most widely adopted graphics API.

Graphics Pipeline

It is an abstract model used to describe a sequence of steps needed in rendering a three-dimensional scene. It enables a computational task to be split into subtasks thus increasing overall efficiency.

Graphics Pipeline

It increases the efficiency of the rendering process, enabling images to be displayed at faster rates.

Application

initializing the window where rendered graphics will be displayed;

Graphics Processing Unit (GPU)

Application stage sends data to the _________

Geometry Processing

determining the position of each vertex of the geometric shapes to be rendered

Vertex Shader

Geometry Processing stage is implemented by a program known as _______ __________

Rasterization

determining which pixels correspond to the geometric shapes to be rendered

Pixel Processing

determining the color of each pixel in the rendered image,

Fragment Shader

Pixel Processing stage involves a program called a __________ ____________

initialized

Creating a window where the rendered graphics will be displayed: The window must be ________ to read the graphics from the GPU framebuffer.

loop

Creating a window where the rendered graphics will be displayed: For animated and interactive applications, the main application contains a ______ that repeatedly re-renders the scene, usually aiming for a rate of 60 FPS.

vertex attributes

Reading data required for the rendering process: This data may include _______ ___________, which describe the appearance of the geometric shapes being rendered.

vertex buffer objects (VBOs), texture buffers

Reading data required for the rendering process: The vertex attribute data is stored in GPU memory buffers called ______ __________ _________, while images to be used as textures are stored in _______ _________.

source code

Reading data required for the rendering process: Lastly, ________ ______ for the vertex shader and fragment shader programs needs to be sent to the GPU, compiled, and loaded.

associations

Sending data to the GPU: The application needs to specify the _________ between attribute data stored in VBOs and attribute variables in the vertex shader program.

multiple attributes

Sending data to the GPU: A single geometric shape may have __________ ___________ for each vertex (such as position and color). The corresponding data is streamed from buffers to variables in the shader during rendering.

shader program

Sending data to the GPU: Frequently, it is also necessary to work with many sets of such associations. Multiple geometric shapes may be rendered by the same ________ ___________.

shader program

Sending data to the GPU: Each shape may also be rendered by a different _________ __________.

vertex array objects (VAOs)

Sending data to the GPU: These sets of associations can be managed using ________ _________ ___________. This stores this information and can be activated and deactivated as needed during the rendering process.

Mesh

Geometry Processing: The shape of a geometric object is defined by a _______, a collection of points that are grouped into lines or triangles

Vertex

Geometry Processing: Apart from the object’s overall shape, additional information may be required to describe how the object should be rendered. The properties or attributes that are specific to rendering each individual point are grouped together into a data structure called a _________.

position

Geometry Processing: A vertex should contain the three-dimensional _________ of the corresponding point.

color

The additional data contained by a vertex often includes the following: • A _______ to be used when rendering the point

Texture coordinates

The additional data contained by a vertex often includes the following: • ___________ ____________ (or UV coordinates), which indicate a point in an image that is mapped to the vertex

Normal vector

The additional data contained by a vertex often includes the following: • A ________ ____________, which indicates the direction perpendicular to a surface and is typically used in lighting calculations

vertices

During Geometry Processing, the vertex shader is applied to each of the _________; each attribute variable in the shader receives data from a buffer according to previously specified associations.

final position

The primary purpose of the vertex shader is to determine the _____ __________ of each of the points being rendered. This is typically calculated from a series of transformations.

Model transformation

The collection of points defining the intrinsic shape of an object may be translated, rotated, and scaled. Hence, the object appears to have a particular location, orientation, and size with respect to a virtual three-dimensional world.

world space

The coordinates expressed from this frame of reference are in ______ _______. In this space, the origin is at the center of the scene.

View transformation

Coordinates in this context are said to be in view space.

View space (or camera space, or eye space)

It is the result when world-space coordinates are transformed to coordinates in front of the user's view.

Projection transformation

Any points outside the specified region are discarded or clipped from the scene;

Clip Space

coordinates expressed at the Projection transformation stage are in _____ _______.

Rasterization

Once the vertex shader has specified the final positions of each vertex, the ____________ stage begins.

Line Strip

The points themselves must first be grouped into the desired type of geometric primitive: points, lines, or triangles, consisting of sets of 1, 2, or 3 points. For lines and triangles, additional information must be specified. For example, an array of points [A, B, C, D, E, F] is to be grouped into lines. They could be grouped in disjoint pairs, such as (A, B), (C, D), (E, F), producing a set of disconnected line segments. They could also be grouped in overlapping pairs, such as (A, B), (B, C), (C, D), (D, E), (E, F), producing a set of connected line segments (called a ______ _______).

OpenGL

The type of geometric primitive and method for grouping points is specified using an __________ function parameter when the rendering process begins.

Primitive Assembly

The process of grouping points into geometric primitives is termed _________ __________. The next step is to identify which pixels correspond to the interior of each geometric primitive. A criterion must be specified to clarify which pixels are in the interior.

Fragment

It is created for each pixel corresponding to the interior of a shape.

Fragment

It is a collection of data used to determine the color of a single pixel in a rendered image.

Raster Position

The data stored in a fragment always includes the ______ _________, also called pixel coordinates.

Pixel Coordinates

Raster Position can also be called _____ ___________

Pixel Processing

The primary purpose of this stage is to determine the final color of each pixel, storing this data in the color buffer within the framebuffer.

Fragment Shader

During the first part of the pixel processing stage, a program called the __________ __________ is applied to each of the fragments to calculate their final color.

base color

Data globally available during rendering, such as the following: • A ______ ________ applied to the entire shape

vertex colors

Data globally available during rendering, such as the following: • Colors stored in each fragment (interpolated from _______ _______)

Textures

Data globally available during rendering, such as the following: • ________ (images applied to the surface of the shape), where colors are sampled from locations specified by texture coordinates

Light sources

Data globally available during rendering, such as the following: • ______ _________, whose relative position and/or orientation may lighten or darken the color, depending on the direction the surface is facing at a point, specified by normal vectors