Tutorials
0 - Introduction
1 - Hello, triangle!
2 - Hello, rectangle!
3 - Unit rectangle
4 - Scaled unit rectangle
5 - Pixel positions
6 - Default vertex shader
7 - Circle by the fragment shader
8 - Iterations and the Mandelbrot set
9 - Macros and the Julia set
10 - Using textures as output
11 - Uniforms and interactions
12 - Time marching
Default vertex shader
The vertex shader below, which was also presented in the previous example is the default vertex shader in Abubu.Solver class.
#version 300 es
precision highp float ; // high percision for float variables
precision highp int ; // high percision for integer variables
in vec4 position; // position of vertices as input of the shader
out vec2 pixPos ; // pixel positions (out to fragment shader)
out vec2 cc ; // pixel positions (out to fragment shader)
// Main body of the vertex shader
void main() {
pixPos = position.xy ; // interpolate based on xy values
cc = position.xy ; // interpolate based on xy values
gl_Position = vec4(
position.x*2.-1., /* x-coordinate */
position.y*2.-1., /* y-coordinate */
position.z, /* z-coordinate */
1.0);
}
If no vertex shader is provided to the Abubu.Solver, a vertex shader similar to the one above will be assumed. This shader is versatile enough for almost any computational need that we encountered when using Abubu.js.
We modified the previous example to the one below.
<!DOCTYPE html>
<html>
<!-- Head -->
<head>
<script src='http://abubujs.org/libs/Abubu.latest.js'
type='text/javascript'></script>
</head>
<!-- body of the html page -->
<body>
<canvas id="canvas_1"
width=512 height=512
style="border:1px solid #000000;" >
<!-- This message is displayed if canvas is not available -->
Your browser does not support the HTML5 canvas tag.
</canvas>
</body>
<!--!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-->
<!-- NOTICE THE VERTEX SHADER IS REMOVED -->
<!--!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!-->
<!--&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&-->
<!-- fragment shader -->
<!--&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&-->
<script id='fshader' type='shader'>#version 300 es
precision highp float ;
precision highp int ;
out vec4 outcolor ; /* output of the shader
pixel color */
in vec2 pixPos ; /* input from vertex shader */
in vec2 cc ; /* input from vertex shader */
// Main body of the shader
void main() {
/* setting r,g,b,a values of the output color as an
opaque red */
outcolor = vec4(pixPos.x,0.,0.,1.) ;
return ;
}</script>
<!--&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&-->
<!-- Main script -->
<!--&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&&-->
<script>
// get the shader source by its id ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
function source(id){
return document.getElementById(id).text ;
}
// Get the canvas ------------------------------------------------------
var canvas_1 = document.getElementById('canvas_1') ;
// Setup a solver ------------------------------------------------------
var renderer = new Abubu.Solver( {
/* NO VERTEX SHADER PROVIDED */
fragmentShader : source('fshader'),
canvas : canvas_1,
} ) ;
// rendering (running) the solver
renderer.render() ;
</script>
</html>
If you open this page in the browser it will produce the page below:
which is identical to the result from the previous example.