What is CAD?
Imagine you have a huge set of digital building blocks. Instead of using your hands and real blocks, you use a special program on a computer to build things. This is what **CAD (Computer-Aided Design)** is! It lets engineers, architects, and designers create 2D and 3D drawings of anything, from a tiny screw to an entire car. It's like a super-powered digital drawing board.
The Fundamentals
At its heart, CAD is about creating and manipulating virtual shapes. The key fundamentals are:
2D vs. 3D
Think of **2D** as a flat drawing, like a picture on a piece of paper. **3D** is a solid object you can walk around and see from all sides, like a real-life model.
Modeling
This is the process of creating a shape. You start with a simple idea and use tools to turn it into a full digital object. It's like sculpting, but in a virtual world.
Editing
CAD makes it easy to change things. You can move, resize, or delete parts of your design without having to start over. It's like having a magic eraser and a perfect ruler.
Basic CAD Definitions
Every field has its own special words. Here are some simple definitions you'll hear in CAD:
Wireframe
A shape made of only lines and points, like a see-through skeleton. It has no filled-in surfaces.
Solid Model
A filled-in, complete shape, like a real, solid block. This is what you would use to make a physical object.
Extrude
A tool that pushes a flat, 2D shape (like a circle) to make it 3D (like a cylinder). Think of squeezing a star shape out of a cookie dough press to make a 3D star.
Revolve
A tool that spins a 2D shape around a line to create a 3D object, like spinning a coin on a table to create a sphere.
Fillet / Chamfer
A tool to round off a sharp corner (**Fillet**) or cut a corner at an angle (**Chamfer**). This is used to make parts safer or look better.
Vertex (Point)
A specific coordinate in 3D space, like $(x, y, z)$. It's the most basic building block of any model.
Edge
A straight or curved line that connects two vertices.
Face / Surface
A flat or curved region bounded by edges, like the side of a cube or the curved surface of a sphere.
Mesh
A collection of vertices, edges, and faces that together form a shape. This is how most models are stored in common file formats like OBJ.
Solid Model
A fully defined 3D volume, as if the object were a real, solid block with mass and features.
Extrude
A tool that pushes a flat, 2D shape to make it a 3D solid. Imagine squeezing a circle out of a tube to create a cylinder.
Revolve
A tool that spins a 2D sketch around a central axis to create a 3D object, like spinning a coin to form a sphere.
Fillet / Chamfer
Tools used to modify sharp corners. A **Fillet** rounds off a corner, while a **Chamfer** cuts it at an angle.
Parametric Model
A model that is defined by rules or parameters. This allows you to easily change its dimensions or shape without starting over.
Assembly
A collection of individual parts fitted together to create a larger, more complex object, like an entire engine made from a variety of components.
HDRI (High Dynamic Range Image)
A special 360-degree image used in rendering to provide realistic lighting and reflections for a scene.
Ray Tracing
A rendering technique that simulates how light bounces off surfaces to create highly realistic shadows, reflections, and lighting effects.
Shapes in CAD
All designs are built from simple shapes. Here are some of the most common ones you'll use.
Rectangle
Circle
Triangle
Cylinder
Cube
Sphere
Your CAD Playground
Use your mouse to draw on the canvas below. This is just a simple example of how a computer can capture your drawing. It’s the very first step in making a digital design!