How to make a 3D Renderer [Explained Simply]

Summary

This tutorial guides viewers through the process of creating a simple 3D renderer using C++ and the SDL library. The video explains how to project 3D objects onto a 2D screen using weak perspective projection and rotate the object around the X and Y axes using rotation matrices. It demonstrates how to define points, vertices, and handle the rendering loop. The video provides an easy-to-follow approach, simplifying complex concepts for beginners, and concludes with a rotating 3D cube as the end result, encouraging viewers to subscribe for more content.

Takeaways

• 😀 The tutorial shows how to create a simple 3D renderer using C++ and SDL, capable of rendering and rotating 3D objects.
• 😀 The main challenge addressed is how to project 3D objects onto a 2D screen using weak perspective projection.
• 😀 The weak perspective projection formula scales 3D coordinates based on the focal length (fov) and the object's distance along the z-axis.
• 😀 A rotation matrix is introduced to rotate the 3D object around the X and Y axes.
• 😀 The formula for rotating points in 3D space involves multiplying the original coordinates with specific rotation matrices.
• 😀 SDL is used for window creation and basic 2D line drawing, but it does not directly handle 3D rendering.
• 😀 The tutorial emphasizes using rotation matrices for transforming 3D coordinates into rotated positions in space.
• 😀 The code provides a basic structure for rendering a rotating cube, with points and vertices defined for the cube's geometry.
• 😀 A loop is implemented to continuously rotate the cube and project the transformed points onto the 2D screen.
• 😀 The projection and rotation functions are simplified for coding ease, and the final output shows a rotating 3D cube in a 2D space.
• 😀 The video is aimed at beginners, providing a non-technical overview of 3D rendering concepts using simple math and coding practices.

Q & A

What is the main objective of the video tutorial?

The main objective of the video tutorial is to show how to create a simple 3D renderer in C++ using the SDL library, which can render 3D vertices and rotate them along the X and Y axes.

What problem does the tutorial address when rendering 3D objects to a 2D screen?

The tutorial addresses the problem of how to project a 3D object onto a 2D screen. It explains how to use weak perspective projection to achieve this.

What is weak perspective projection, and how is it used in this tutorial?

Weak perspective projection is a technique where a 3D object's coordinates are transformed into 2D screen space using a formula involving the focal length (or field of view, FOV) and the object's position in 3D space. In the tutorial, this is used to calculate the 2D projection of the 3D object.

How is the formula for projection derived in the tutorial?

The projection formula is derived using similar triangles, where the ratio of corresponding sides of the triangles remains constant. The formula involves multiplying the 3D x-coordinate by the FOV and dividing by the sum of the FOV and the z-coordinate.

How does the tutorial handle 3D rotations?

The tutorial explains how to rotate 3D objects using rotation matrices. It simplifies these matrices for implementation in code, allowing the rotation of points in 3D space along the X and Y axes.

What role does the SDL library play in the tutorial?

The SDL library is used to create the window and handle 2D drawing of lines. Although SDL is not a 3D graphics library, it is used here to render 3D projections onto a 2D screen.

Why does the tutorial use frame-independent timing?

Frame-independent timing ensures that the rotation of the object happens at a consistent speed regardless of the frame rate. This is done by calculating the rotation based on time (delta time) instead of relying on the frame count.

What is the significance of the 'rotation matrix' mentioned in the tutorial?

The rotation matrix is a mathematical construct that, when applied to the coordinates of a 3D point, rotates that point around a specified axis. In the tutorial, it's used to apply rotations to the cube before projecting it onto the screen.

What is the purpose of the Point 3D and Point 2D structures in the code?

The Point 3D structure represents a point in 3D space, while the Point 2D structure is used to map these points onto the 2D screen. This distinction helps in handling 3D coordinates and their 2D projections separately.

What happens when the program is run at the end of the tutorial?

When the program is run, a rotating cube is displayed on the screen. The cube rotates smoothly based on the specified rotation matrices, and the 3D vertices are projected onto a 2D window using the weak perspective projection technique.