Graphics Basics

Welcome to the foundational concepts of computer graphics as documented by MSDN. This section covers the essential building blocks and principles required to understand and implement graphics rendering.

Pixels and Resolution

At the most fundamental level, a digital image is composed of a grid of tiny colored dots called pixels. Each pixel represents a single point on the display. The number of pixels horizontally and vertically determines the image's resolution. Higher resolution means more pixels, leading to finer detail and sharper images.

• Resolution: Typically expressed as width × height (e.g., 1920 × 1080 pixels).
• Aspect Ratio: The ratio of the image width to its height (e.g., 16:9).

Color Models

Colors in digital graphics are represented using various color models. The most common ones include:

RGB (Red, Green, Blue)

This additive color model is widely used in displays. Each color is represented by a combination of red, green, and blue light. Values typically range from 0 to 255 for each component, or expressed as percentages.

RGBA (Red, Green, Blue, Alpha)

This is an extension of RGB that includes an alpha channel. The alpha channel controls the opacity of the color, where 0 is fully transparent and 1 (or 255) is fully opaque. This is crucial for blending and layering effects.

Coordinate Systems

Graphics are rendered within a coordinate system. The specific origin and orientation of this system can vary, but a common system used in computer graphics is a 2D Cartesian coordinate system:

• Origin: Typically at the top-left corner of the screen or window.
• X-axis: Increases to the right.
• Y-axis: Increases downwards.

For 3D graphics, a Z-axis is introduced, often pointing out of the screen (towards the viewer) or into the screen, depending on the convention.

Basic Primitives

The fundamental shapes that graphics APIs use to draw are called primitives. These are the simplest geometric entities:

• Points: A single location in space, defined by its coordinates.
• Lines: A straight connection between two points.
• Triangles: The most basic polygon, with three vertices. Complex shapes are often constructed by tessellating them into many triangles.
• Polygons: Closed shapes defined by a sequence of vertices.

Rasterization

Rasterization is the process of converting vector graphics (geometric descriptions like lines and polygons) into a raster image (a grid of pixels). This involves determining which pixels on the screen are covered by a given geometric shape and assigning them an appropriate color.

Rendering

Rendering is the overall process of generating an image from a 2D or 3D model by means of computer programs. It takes geometric data, textures, lighting information, and camera views to produce the final pixel data that is displayed.

Key Rendering Concepts

• Vertices: The points that define geometric shapes.
• Edges: The lines connecting vertices.
• Faces: The surfaces enclosed by edges (especially in 3D, often triangles).
• Shading: The process of calculating the color of surfaces based on lighting, material properties, and the angle of incidence.

Understanding these basic concepts is crucial before delving into more complex graphics techniques and APIs.