glsl-smaa

SMAA (Enhanced Subpixel Morphological Antialiasing) post-processing; WebGL (OpenGL ES 2.0) implementation with no fluff. All credit goes to the incredible work here (iryoku) and there (beakbeak).

Installation

npm install glsl-smaa

Usage

Three passes are required to apply the effect:

             |input|------------------·
                v                     |
      [ SMAA*EdgeDetection ]          |
                v                     |
            |edgesTex|                |
                v                     |
[ SMAABlendingWeightCalculation ]     |
                v                     |
            |blendTex|                |
                v                     |
  [ SMAANeighborhoodBlending ] <------·
                v
             |output|

You would typically set this up as part of a post-processing chain with FBOs.

See the demo and its source for an example with REGL.

Attributes

Attributes required for all vertex shaders:

Name	Type	Description
aPosition	vec2	Screen vertices.

Uniforms and defines

Uniforms required for all shaders:

Name	Type	Description
resolution	vec2	The framebuffer size.

#define can be preprended to the shaders to overwrite default settings. Typically:

const frag = `#define SMAA_PRESET_HIGH
${PRESETS}
${SMAA_WEIGHTS_FRAG}
`;

edges.vert

N/A

edges-<edge-detection-method>.frag

You can use one of the 3 following edge detection method:

• Depth: the fastest but it may miss some edges.

• Luma: more expensive than depth edge detection, but catches visible edges that depth edge detection can miss.

• Color: the most expensive one but catches chroma-only edges.

Defines:

#define SMAA_THRESHOLD 0.1
#define SMAA_LOCAL_CONTRAST_ADAPTATION_FACTOR 2.0

Name	Default [Range]	Description
SMAA_THRESHOLD	0.1 [0, 0.5]	Specifies the threshold or sensitivity to edges. Lowering this value you will be able to detect more edges at the expense of performance. Range: [0, 0.5]. 0.1 is a reasonable value, and allows to catch most visible edges. 0.05 is a rather overkill value, that allows to catch 'em all.
SMAA_LOCAL_CONTRAST_ADAPTATION_FACTOR	2.0	If there is an neighbor edge that has SMAA_LOCAL_CONTRAST_FACTOR times bigger contrast than current edge, current edge will be discarded. This allows to eliminate spurious crossing edges, and is based on the fact that, if there is too much contrast in a direction, that will hide perceptually contrast in the other neighbors.

Uniforms:

luma-edges.frag

Name	Type	Description
colorTex	sampler2D	The input color framebuffer.

color-edges.frag

Name	Type	Description
colorTex	sampler2D	The input color framebuffer.

depth-edges.frag

Name	Type	Description
depthTex	sampler2D	The input depth framebuffer.

---

smaa-weights.(vert|frag)

Defines from presets.glsl:

# Use presets:
#define SMAA_PRESET_LOW
#define SMAA_PRESET_MEDIUM
#define SMAA_PRESET_HIGH
#define SMAA_PRESET_ULTRA

# or individually setting:
#define SMAA_THRESHOLD 0.1
#define SMAA_MAX_SEARCH_STEPS 16
#define SMAA_MAX_SEARCH_STEPS_DIAG 8
#define SMAA_CORNER_ROUNDING 25

# and optionally disable diagonal and corner detection:
#define SMAA_DISABLE_DIAG_DETECTION
#define SMAA_DISABLE_CORNER_DETECTION

Name	Default [Range]	Description
SMAA_THRESHOLD	0.1 [0, 0.5]	Should the same as for the edge pass.
SMAA_MAX_SEARCH_STEPS	16 [0, 112]	Specifies the maximum steps performed in the horizontal/vertical pattern searches, at each side of the pixel. In number of pixels, it's actually the double. So the maximum line length perfectly handled by, for example 16, is 64 (by perfectly, we meant that longer lines won't look as good, but still antialiased.
SMAA_MAX_SEARCH_STEPS_DIAG	8 [0, 20]	Specifies the maximum steps performed in the diagonal pattern searches, at each side of the pixel. In this case we jump one pixel at time, instead of two.
SMAA_CORNER_ROUNDING	25 [0, 100]	Specifies how much sharp corners will be rounded.

Uniforms:

Name	Type	Description
edgesTex	sampler2D	The framebuffer with edges.
areaTex	sampler2D	Precalculated textures loadable from textures.js base64 urls.
searchTex	sampler2D	Precalculated textures loadable from textures.js base64 urls.

---

smaa-blend.(vert|frag)

Name	Type	Description
colorTex	sampler2D	The input color framebuffer.
blendTex	sampler2D	The framebuffer with weights.

---

License

Copyright (C) 2013 Jorge Jimenez ([email protected]) Copyright (C) 2013 Jose I. Echevarria ([email protected]) Copyright (C) 2013 Belen Masia ([email protected]) Copyright (C) 2013 Fernando Navarro ([email protected]) Copyright (C) 2013 Diego Gutierrez ([email protected])

MIT. See license file.