• Interactive Poisson Blending on GPU
• Simplest and Fastest GLSL Edge Detection using Fwidth

# Tag: GLSL

## Implementing Instagram Filters: Brannan, Earlybird

This series illustrate my shaders on Shadertoy.com, which renders Instagram filters in real time. Brannan Filter Brannan filter emphasizes the grey and green colors, and paints a metallic tint upon the photos. Click the mouse for comparison. I write this shader to stylize your photos in batch on my own ShaderToy renderer 🙂 (To be…

## Dotted Drawing / Sketch Effect

After lunch, I want to replicate the sketch shader I wrote for the Pencil-vs-Camera project. Additionally, I wrote a one-pass shader for dotted drawing / sketch post processing effect, which I think is more aesthetically pleasing. Dotted Drawing Demo Click on the play button in the left bottom corner of the embedded ShaderToy window below, to…

## Unified Gnomonic and Stereographic Projections

Gnomonic projection, or rectilinear projection, together with stereographic projection, are two most commonly used projection in rendering 360 degree videos, or other VR applications. Recently, I found the inverse converting function from screen coordinates to the two projections can be unified within a single function. It’s not really surprising since both projection uses spherical lens,…

## Equirectangular Projection, Gnomonic Projection, and Cubemaps

Gnomonic Projection Background According to MathWorld, the gnomonic projection is a nonconformal map projection obtained by projecting points (or ) on the surface of sphere from a sphere’s center O to point P in a plane that is tangent to a point S (Coxeter 1969, p. 93). In a gnomonic projection, great circles are mapped…

## 0-4 Order of Spherical Harmonics

Spherical Harmonics is widely used in Computer Graphics. They are analogue to Fourier basis on a sphere, consists of a set of orthogonal functions to represent functions defined on the surface of a sphere. However, they are very tricky to implement due to lots of constants and integral functions. Here is a real-time visualization that…

Taken iq’s background transparent code and Dr. Neyret’s advice: This shader can be used for rendering pop-up images in a 3D environment.

Today, I wrote a shader for foveated rendering uisng Prof. Neyret’s QuadTree: https://www.shadertoy.com/view/Ml3SDf The basic idea is:  Calculate the depth of the QuadTree using the distance between the current coordinate to the foveat region Use the depth as the mipmap level to sample from the texture Code below:

## Bilateral Filter to Look Younger on GPU

Bilateral filter can be used to smooth the texture while preserving significant edges / contrast. Below shows a live demo in ShaderToy. Press mouse for comparison. Thanks to mrharicot’s awesome bilateral filter: https://www.shadertoy.com/view/4dfGDH With performance improvement proposed by athlete. With gamma correction by iq: https://www.shadertoy.com/view/XtsSzH   Skin detection forked from carlolsson’s Skin Detection https://www.shadertoy.com/view/MlfSzn#

## Interactive Poisson Blending on GPU

Recently, I have implemented two fragment shaders for interactive Poisson Blending (seamless blending).  Here is my real-time demo and code on ShaderToy: Press 1 for normal mode, press 2 for mixed gradients, press space to clear the canvas. Technical Brief I followed a simplified routine of the Poisson Image Editing paper [P. Pérez, M. Gangnet,…

## Simplest and Fatest GLSL Edge Detection using Fwidth

GLSL Edge Detection Yesterday, I read 834144373’s ShaderToy code which did GLSL Edge Detection in 97 chars, it was really simple and fast:

Meanwhile, the rendering result is astonishingly awesome: However, there are some noise from the GLSL edge detection. Thus, I have made a little improvement on this algorithm and produced cleaner edges in this ShaderToy…