https://github.com/erkaman/planar_proj_shadows

Demo of Planar Projected Shadows in regl
https://github.com/erkaman/planar_proj_shadows

demo matrix opengl regl shadow shadows webgl

Last synced: 3 days ago
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Demo of Planar Projected Shadows in regl

• Host: GitHub
• URL: https://github.com/erkaman/planar_proj_shadows
• Owner: Erkaman
• License: mit
• Created: 2017-03-11T11:39:35.000Z (over 7 years ago)
• Default Branch: gh-pages
• Last Pushed: 2017-03-11T20:12:30.000Z (over 7 years ago)
• Last Synced: 2024-08-12T03:04:38.667Z (3 months ago)
• Topics: demo, matrix, opengl, regl, shadow, shadows, webgl
• Language: JavaScript
• Homepage: https://erkaman.github.io/planar_proj_shadows/planar_proj_shadows.html
• Size: 167 KB
• Stars: 32
• Watchers: 4
• Forks: 7
• Open Issues: 0
• Metadata Files:
  • Readme: README.md
  • License: LICENSE

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README

        
# planar_proj_shadows

Demo of Planar Projected Shadows implemented with [regl](https://github.com/mikolalysenko/regl).

![](img.jpg)

[Demo here](https://erkaman.github.io/planar_proj_shadows/planar_proj_shadows.html)

# Implementation Details

This is an implementation of Planar Projected Shadows, described in

the excellent book [Real-Time

Shadows](https://www.amazon.com/Real-Time-Shadows-Elmar-Eisemann/dp/1568814380).

Basically, if we only want a plane to receive shadows, we do not need

any Shadow Maps or Shadow Volumes. Instead, we simply define a

projection matrix *P* that project onto that plane. To then render the

shadows, we render the shadow casting geometry, but instead of

rendering them normally, (in vertex shader)we project them onto the plane using the

matrix *P*, and(in fragment shader) we render the geometry in black.

But note that the trick only works when casting shadows onto a plane.

# Build

First install all dependencies by doing

```bash

npm install

```

To then run the demo, do

```bash

npm run start

```