Raytracing on a Graphing Calculator (again)
TLDRThis video showcases the development of a raytracing engine on a TI84 calculator, capable of rendering images with textures, reflections, HDR, and global illumination. The creator addresses limitations from a previous attempt, rewriting the program in C++ for efficiency and speed, achieving an 80x speedup. The script explores techniques like fixed point math for performance and radiosity for realistic lighting. The result is a photorealistic raytraced scene on a calculator, demonstrating impressive capabilities and a significant leap from the device's usual graphics.
Takeaways
- 📱 A raytracing engine was developed to run on a TI84 calculator, showcasing its capabilities to handle complex graphics tasks.
- 🔄 The original raytracer was slow, taking 6 hours to render an image, but the new version improved performance significantly.
- 🛠️ The switch from TI-BASIC to C++ for programming the calculator provided numerous benefits, including faster execution and better code management.
- 🎨 The new raytracer supports advanced graphics features such as textures, reflections, HDR, gamma-correct rendering, dithering, and global illumination.
- 🚀 An 80x speedup was achieved by rewriting the raytracer in C++, reducing the rendering time from 6 hours to 3 minutes.
- 🔢 The use of fixed-point arithmetic instead of floating-point numbers improved performance due to the lack of hardware optimization for floats on the calculator's Z80 processor.
- 💡 The calculator's display was revealed to have a 32,768 color 320x240 resolution, comparable to the Super Nintendo, allowing for better image quality.
- 🏗️ Scenes in the raytracer were made more complex by adding walls, a ceiling, and another sphere, moving beyond the simple scenes of the original.
- 🌡️ The implementation of Lambert's Law and the inverse-square law helped to simulate realistic lighting behavior in the rendered scenes.
- 🌈 Dithering was used to address color banding issues due to the calculator's 15-bit color limitation, creating smoother color transitions.
- 🌍 Global illumination was added to simulate indirect light bounces in the scene, enhancing the realism of the rendered image.
Q & A
What is the main achievement of the video script?
-The main achievement is the development of a raytracing engine that runs on a TI84 calculator, capable of rendering images with features like textures, reflection, HDR, gamma-correct rendering, dithering, and global illumination.
Why was the initial raytracing program on the calculator slow?
-The initial program was slow because it was written in TI-BASIC, an interpreted language, which added overhead to every math operation and limited the use of colors and variable names.
What language and toolchain was used to rewrite the raytracing program for better performance?
-The program was rewritten in C++ using the toolchain provided by Matt Waltz and contributors to the CE Programming project, which allowed for compiled code and more efficient memory usage.
How much faster is the new raytracing version compared to the old one?
-The new version is approximately 80 times faster than the old one, taking about 3 minutes to render an image that previously took nearly 6 hours.
What is the significance of using fixed point numbers instead of floating point numbers in the raytracing calculations?
-Fixed point numbers are used to simplify the calculations by treating the decimal as always being in the same place, which speeds up operations significantly on the Z80 processor inside the TI84 calculator.
What is the color display capability of the TI84 calculator mentioned in the script?
-The TI84 calculator has a 32,768 color 320x240 display, which is comparable to the Super Nintendo and an improvement over the TiBASIC graphical specs.
What is the concept of Lambert's Law in the context of the raytracer?
-Lambert's Law refers to the principle that light intensity on an object decreases the more the surface points away from the light source, affecting how pixels are shaded in the output.
What is the purpose of dithering in the raytracing renderer?
-Dithering is used to fix the issue of color banding by mixing pixels of different colors along a transition, creating the illusion of a larger color palette and smoothing out the colors.
How does the renderer handle HDR and gamma correction?
-The renderer uses a lookup table to perform HDR and gamma correction, adjusting pixel values to preserve detail in areas that would otherwise appear too dim or too bright.
What is global illumination and how does it differ from direct illumination?
-Global illumination refers to light bouncing off objects in the scene from various directions, creating a more realistic lighting effect compared to direct illumination, which only considers light coming directly from the source.
What is the radiosity algorithm and how is it used in the raytracer?
-The radiosity algorithm computes a lightmap for each object in the scene, which tracks how much light is hitting the object. It simulates light bouncing around the scene by adding up the light contributed by all other objects, leading to a more accurate lighting representation.
How does the script conclude regarding the potential for future improvements and the current state of the raytracer?
-The script concludes by acknowledging the potential for further improvements, such as adding support for triangle meshes, different lighting options, and refractive materials. However, it also celebrates the current achievement of faster and more photorealistic raytracing on a TI84 calculator.
Outlines
😲 Raytracing on a TI84 Calculator
The script introduces a raytracing engine developed for a TI84 calculator, capable of rendering images with advanced graphical features such as textures, reflections, HDR, gamma-correct rendering, dithering, and global illumination. The author addresses the limitations of their previous raytracing program, which was slow due to the use of the TI-BASIC interpreted language, and discusses the switch to C++ for improved performance and flexibility. The new version of the raytracer is shown to be significantly faster, taking only 3 minutes to render an image compared to the previous 6 hours, and is capable of displaying a 32,768 color 320x240 display, rivaling the Super Nintendo in quality.
🔍 Enhancing Raytracing with Fixed Point and Scene Complexity
The script delves into the technical aspects of improving the raytracer's speed and scene complexity. It discusses the inefficiency of floating-point arithmetic on the calculator's Z80 processor and the adoption of fixed-point arithmetic to speed up calculations. The author also talks about the updated 2015 TI84 Plus CE model's Zilog eZ80 processor with 24-bit wide registers, which allows for faster rendering. The script further explores the enhancement of scene complexity by adding walls, a ceiling, and another sphere, as well as the implementation of Lambert's Law and the inverse-square law for more realistic lighting. The introduction of texturing and dithering techniques to improve visual quality is also covered.
🎨 Achieving Photorealism with Global Illumination and Color Techniques
The script describes efforts to achieve photorealism in the raytraced images by addressing the linear scaling assumption of light intensity and introducing a lookup table to correct for the non-linear nature of sRGB values. It also discusses the implementation of tone mapping for HDR and the addition of global illumination to simulate indirect light bouncing in a scene. The use of radiosity to approximate this effect is explained, along with the rendering of direct and indirect light for a more realistic appearance. The script mentions color bleeding as a subtle effect that contributes to realism and concludes with the creation of a mirror ball effect and a comparison of the calculator's rendering capabilities with those of a modern computer using Blender.
🚀 Pushing the Limits of Raytracing on Calculators
The script wraps up by highlighting the impressive capabilities of the raytracer on a TI84 calculator, which now includes reflection, global illumination, HDR, gamma-correct rendering, point lights, and textures. It provides a comparison of the rendering times between the calculator and a modern computer, noting a significant speedup from the original version. The author reflects on potential improvements and extensions to the raytracer, such as optimizing fixed-point functions, reducing redundant calculations, and adding support for more complex shapes and lighting. The script ends with an invitation for viewers to contribute to the project on GitHub and expresses satisfaction with the current state of the raytracer on the calculator.
Mindmap
Keywords
💡Raytracing
💡TI84 Calculator
💡TI-BASIC
💡C++
💡Fixed Point Arithmetic
💡Global Illumination
💡Dithering
💡Reflection
💡HDR (High Dynamic Range)
💡Gamma Correction
Highlights
The image was rendered using a raytracing engine on a TI84 calculator, showcasing advanced features like textures, reflection, HDR, and global illumination.
The original raytracer had limitations including slow speed, using TI-BASIC which is interpreted, and restrictions on colors and variable names.
Switching to C++ for the project allowed for compiled code, easier documentation, and direct memory access, significantly improving performance.
The new C++ version achieved an 80x speedup, reducing the rendering time from 6 hours to 3 minutes.
Fixed point arithmetic was used to optimize performance on the calculator's Z80 processor, which lacks hardware optimizations for floating point numbers.
The TI84 Plus CE model's Zilog eZ80 processor with 24-bit wide registers was leveraged for faster fixed point calculations.
Scene complexity was increased by adding walls, a ceiling, and another sphere, moving beyond the simple scenes of the original raytracer.
Lambert's Law and the inverse-square law were implemented to model how light falls off based on distance and angle from the light source.
Texturing was introduced to add realism by projecting images onto objects in the scene during rendering.
Dithering was used to smooth out color transitions limited by the calculator's 15-bit color display.
A lookup table was implemented to correct for the non-linear relationship between RGB values and perceived brightness.
Global illumination was simulated using radiosity to account for light bouncing around the scene, improving realism.
Color bleeding effect was achieved, where colored objects reflect light and tint surrounding objects.
A mirror ball was added to demonstrate reflection capabilities of the raytracer, a hallmark of raytracing technology.
A comparison was made with a Blender render to highlight the calculator's capabilities, showing it is not far off in terms of rendering quality.
The final rendering time on the calculator was 14 minutes, a significant improvement from the original 6 hours.
The source code is available on Github for others to contribute and add features like triangle meshes, directional light, and refractive materials.
The video concludes with the potential for real-time raytraced Minecraft on a calculator, showcasing the progress made in calculator graphics capabilities.
Transcripts
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