gamma

Gamma is a substrate for graphics software, such as games and data visualization tools. It presents a simple, composable language for representing GLSL shaders.

• Tutorial, Tutorial repo
• Examples repo
• Docs
• Rationale

Benefits:

• Decouple, simplify, abstract shader code
• Release graphics pipeline from rigid demands of shaders
• Create composable, multiplatform shader libraries
• Quickly build higher-level GL libraries

Technically, Gamma is an EDSL that hosts GLSL within Clojurescript. It is inspired by Carlos Scheidegger's Lux and Conal Elliot's Vertigo and Pan. Gamma targets the WebGL subset of the OpenGL ES 1.0 Shading Language. Gamma can be used a la carte to compile shader source, without adopting Clojure/Clojurescript for your runtime application.

Gamma is very early alpha.

Installation

Add the following to your project.clj's :dependencies

[kovasb/gamma "0.0-135"]

Be sure to use clojurescript 0.0-3292 or above:

[org.clojure/clojurescript "0.0-3292"]

"Hello Triangle" Tutorial

See the batteries-included Hello Triangle example project for how to set up your project, and how to invoke the generated shader so that a triangle appears on screen.

Lets use Gamma at the REPL to create a minimum shader program for drawing a red triangle.

(require '[gamma.api :as g])
(require '[gamma.program :as p])

;; shader input attribute will be a vec2 of x,y coordinates
(def vertex-position (g/attribute "a_VertexPosition" :vec2))

;; vertex shader turns input into a vec4, and assigns it to gl_Position
(def vertex-shader {(g/gl-position) (g/vec4 vertex-position 0 1)})

;; fragment shader assigns the rgba value for red to gl_FragColor
(def fragment-shader {(g/gl-frag-color) (g/vec4 1 0 0 1)})

;; compile Gamma into a GLSL program string
(def hello-triangle
  (p/program
    {:vertex-shader vertex-shader
     :fragment-shader fragment-shader}))

Thats it! hello-triangle now contains the GLSL for this shader, and other useful information such as a description of its inputs.

;; print vertex shader glsl
(println (:glsl (:vertex-shader hello-triangle)))
=>
"attribute vec2 a_VertexPosition;
void main(void){
 gl_Position = vec4(a_VertexPosition, 0, 1);
}"

;; print fragment shader glsl
(println (:glsl (:fragment-shader hello-triangle)))
=>
"void main(void){
 gl_FragColor = vec4(1, 0, 0, 1);
}"

;; get shader inputs
(:inputs hello-triangle)
=> #{{:tag :variable, :name "a_VertexPosition", :type :vec2, :storage :attribute}}

Testing

Build the tests:

lein trampoline run -m clojure.main scripts/test_build.clj

Run the tests:

lein trampoline run -m clojure.main scripts/test_run.clj

Or use the shell-script ./scripts/test

Watch for "Waiting for browser to connect ...", then connect browser to http://localhost:9000/test.html

The output of the testing will be sent to the developer console.

License

Copyright © 2015 Kovas Boguta

Distributed under the Eclipse Public License either version 1.0 or (at your option) any later version.