如何使用WebGL和GLSL在J/s文件中运行Shadertoy的着色器

Question

我是着色器编程的新手，我想用WebGL和GLSL创建着色器。为了了解它的实际工作原理，我想测试Shadertoy的着色器。但是，如何从Shadertoy中获取代码，并在J/S文件中实际运行它呢？您只需要将代码从Shadertoy复制到片段着色器中吗？

Answer 1

请参阅以下非常基本的示例。您可以将Shadertoy代码放在片段着色器的mainImage函数中：

(function loadscene() {    
var canvas, gl, vp_size, prog, bufObj = {}, mousepos = [0, 0];
function initScene() {
canvas = document.getElementById( "ogl-canvas");
gl = canvas.getContext( "experimental-webgl" );
if ( !gl )
return;
canvas.addEventListener('mousemove', (e) => {
mousepos = [e.clientX, e.clientY];
});
progDraw = gl.createProgram();
for (let i = 0; i < 2; ++i) {
let source = document.getElementById(i==0 ? "draw-shader-vs" : "draw-shader-fs").text;
let shaderObj = gl.createShader(i==0 ? gl.VERTEX_SHADER : gl.FRAGMENT_SHADER);
gl.shaderSource(shaderObj, source);
gl.compileShader(shaderObj);
let status = gl.getShaderParameter(shaderObj, gl.COMPILE_STATUS);
if (!status) alert(gl.getShaderInfoLog(shaderObj));
gl.attachShader(progDraw, shaderObj);
gl.linkProgram(progDraw);
}
status = gl.getProgramParameter(progDraw, gl.LINK_STATUS);
if ( !status ) alert(gl.getProgramInfoLog(progDraw));
progDraw.inPos = gl.getAttribLocation(progDraw, "inPos");
progDraw.iTime = gl.getUniformLocation(progDraw, "iTime");
progDraw.iMouse = gl.getUniformLocation(progDraw, "iMouse");
progDraw.iResolution = gl.getUniformLocation(progDraw, "iResolution");
gl.useProgram(progDraw);
var pos = [ -1, -1, 1, -1, 1, 1, -1, 1 ];
var inx = [ 0, 1, 2, 0, 2, 3 ];
bufObj.pos = gl.createBuffer();
gl.bindBuffer( gl.ARRAY_BUFFER, bufObj.pos );
gl.bufferData( gl.ARRAY_BUFFER, new Float32Array( pos ), gl.STATIC_DRAW );
bufObj.inx = gl.createBuffer();
bufObj.inx.len = inx.length;
gl.bindBuffer( gl.ELEMENT_ARRAY_BUFFER, bufObj.inx );
gl.bufferData( gl.ELEMENT_ARRAY_BUFFER, new Uint16Array( inx ), gl.STATIC_DRAW );
gl.enableVertexAttribArray( progDraw.inPos );
gl.vertexAttribPointer( progDraw.inPos, 2, gl.FLOAT, false, 0, 0 ); 

gl.enable( gl.DEPTH_TEST );
gl.clearColor( 0.0, 0.0, 0.0, 1.0 );
window.onresize = resize;
resize();
requestAnimationFrame(render);
}
function resize() {
//vp_size = [gl.drawingBufferWidth, gl.drawingBufferHeight];
vp_size = [window.innerWidth, window.innerHeight];
//vp_size = [256, 256]
canvas.width = vp_size[0];
canvas.height = vp_size[1];
}
function render(deltaMS) {
gl.viewport( 0, 0, canvas.width, canvas.height );
gl.clear( gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT );

gl.uniform1f(progDraw.iTime, deltaMS/1000.0);
gl.uniform2f(progDraw.iResolution, canvas.width, canvas.height);
gl.uniform2f(progDraw.iMouse, mousepos[0], mousepos[1]);
gl.drawElements( gl.TRIANGLES, bufObj.inx.len, gl.UNSIGNED_SHORT, 0 );

requestAnimationFrame(render);
}  
initScene();
})();

<script id="draw-shader-fs" type="x-shader/x-fragment">
precision mediump float;
uniform vec2 iResolution;
uniform vec2 iMouse;
uniform float iTime;
void mainImage(out vec4 fragColor, in vec2 fragCoord)
{
vec2 st = fragCoord.xy / iResolution.xy;
fragColor = vec4(st, 0.0, 1.0);
}
void main() 
{
mainImage( gl_FragColor, gl_FragCoord.xy );
}
</script>
<script id="draw-shader-vs" type="x-shader/x-vertex">
attribute vec2 inPos;
void main() 
{
gl_Position = vec4(inPos, 0.0, 1.0);
}
</script>
<canvas id="ogl-canvas" style="border: none"></canvas>