Add nebula shader javascript.

Includes inline GLSL code, as well as a GLES implementation of cnoise.

content/js/nebula_shader.js

@@ -0,0 +1,213 @@
+const ITERATIONS = 3;
+const SCALAR = Math.pow(2.0, 4.0 / 3.0);
+
+let gl, program, buffer;
+
+const vertexShaderSource = `
+    attribute vec2 position;
+    void main() {
+        gl_Position = vec4(position, 0.0, 1.0);
+    }
+`;
+
+const fragmentShaderSource = `
+    precision mediump float; // Specify precision for float variables
+
+    const int ITERATIONS = 3;
+    const float SCALAR = pow(2.0, 4.0/3.0); // Ensure constants have the correct type
+
+    uniform mat4 projection;
+    uniform float eddy_scale;
+    uniform float u_time;
+
+    vec3 mod289(vec3 x) {
+       return x - floor(x * (1.0 / 289.0)) * 289.0;
+    }
+
+    vec4 mod289(vec4 x) {
+       return x - floor(x * (1.0 / 289.0)) * 289.0;
+    }
+
+    vec4 permute(vec4 x) {
+       return mod289(((x*34.0)+1.0)*x);
+    }
+
+    vec4 taylorInvSqrt(vec4 r) {
+       return 1.79284291400159 - 0.85373472095314 * r;
+    }
+
+    vec3 fade(vec3 t) {
+       return t*t*t*(t*(t*6.0-15.0)+10.0);
+    }
+
+    float cnoise(vec3 P) {
+       vec3 Pi0 = floor(P);
+       vec3 Pi1 = Pi0 + vec3(1.0);
+       
+       vec3 Pf0 = fract(P);
+       vec3 Pf1 = Pf0 - vec3(1.0);
+       
+       vec4 ix = vec4(Pi0.x, Pi1.x, Pi0.x, Pi1.x);
+       vec4 iy = vec4(Pi0.yy, Pi1.yy);
+       vec4 iz0 = Pi0.zzzz;
+       vec4 iz1 = Pi1.zzzz;
+       
+       vec4 ixy = permute(permute(ix) + iy);
+       vec4 ixy0 = permute(ixy + iz0);
+       vec4 ixy1 = permute(ixy + iz1);
+       
+       vec4 gx0 = ixy0 * (1.0 / 7.0);
+       vec4 gy0 = fract(floor(gx0) * (1.0 / 7.0)) - 0.5;
+       gx0 = fract(gx0);
+       vec4 gz0 = vec4(0.5) - abs(gx0) - abs(gy0);
+       vec4 sz0 = step(gz0, vec4(0.0));
+       gx0 -= sz0 * (step(0.0, gx0) - 0.5);
+       gy0 -= sz0 * (step(0.0, gy0) - 0.5);
+       
+       vec4 gx1 = ixy1 * (1.0 / 7.0);
+       vec4 gy1 = fract(floor(gx1) * (1.0 / 7.0)) - 0.5;
+       gx1 = fract(gx1);
+       vec4 gz1 = vec4(0.5) - abs(gx1) - abs(gy1);
+       vec4 sz1 = step(gz1, vec4(0.0));
+       gx1 -= sz1 * (step(0.0, gx1) - 0.5);
+       gy1 -= sz1 * (step(0.0, gy1) - 0.5);
+       
+       vec3 g000 = vec3(gx0.x,gy0.x,gz0.x);
+       vec3 g100 = vec3(gx0.y,gy0.y,gz0.y);
+       vec3 g010 = vec3(gx0.z,gy0.z,gz0.z);
+       vec3 g110 = vec3(gx0.w,gy0.w,gz0.w);
+       vec3 g001 = vec3(gx1.x,gy1.x,gz1.x);
+       vec3 g101 = vec3(gx1.y,gy1.y,gz1.y);
+       vec3 g011 = vec3(gx1.z,gy1.z,gz1.z);
+       vec3 g111 = vec3(gx1.w,gy1.w,gz1.w);
+       
+       vec4 norm0 = taylorInvSqrt(vec4(dot(g000, g000), dot(g010, g010), dot(g100, g100), dot(g110, g110)));
+       g000 *= norm0.x;
+       g010 *= norm0.y;
+       g100 *= norm0.z;
+       g110 *= norm0.w;
+       
+       vec4 norm1 = taylorInvSqrt(vec4(dot(g001, g001), dot(g011, g011), dot(g101, g101), dot(g111, g111)));
+       g001 *= norm1.x;
+       g011 *= norm1.y;
+       g101 *= norm1.z;
+       g111 *= norm1.w;
+       
+       float n000 = dot(g000, Pf0);
+       float n100 = dot(g100, vec3(Pf1.x, Pf0.yz));
+       float n010 = dot(g010, vec3(Pf0.x, Pf1.y, Pf0.z));
+       float n110 = dot(g110, vec3(Pf1.xy, Pf0.z));
+       float n001 = dot(g001, vec3(Pf0.xy, Pf1.z));
+       float n101 = dot(g101, vec3(Pf1.x, Pf0.y, Pf1.z));
+       float n011 = dot(g011, vec3(Pf0.x, Pf1.yz));
+       float n111 = dot(g111, Pf1);
+       
+       vec3 fade_xyz = fade(Pf0);
+       vec4 n_z = mix(vec4(n000, n100, n010, n110), vec4(n001, n101, n011, n111), fade_xyz.z);
+       vec2 n_yz = mix(n_z.xy, n_z.zw, fade_xyz.y);
+       float n_xyz = mix(n_yz.x, n_yz.y, fade_xyz.x);
+       return 2.2 * n_xyz;
+    }
+    vec4 effect(vec4 col_in, vec2 texture_coords, vec2 screen_coords ) {
+       float f = 0.0;
+       vec3 uv;
+
+       // Calculate coordinates
+       uv.xy = screen_coords / eddy_scale;
+       uv.z = u_time / 5.0;
+
+       // Create the noise
+       for (int i=0; i<ITERATIONS; i++) {
+          float scale = pow(SCALAR, float(i));
+          f += abs( cnoise( uv * scale ) ) / scale;
+       }
+
+       vec4 colour =  mix( vec4(0.0,0.0,0.0,1.0), col_in, 0.1 + f );
+
+       return colour;
+    }
+
+    void main() {
+       gl_FragColor = effect(vec4(0.0,0.0,1.0,1.0), gl_FragCoord.xy, gl_FragCoord.xy);
+    }
+`;
+
+function compileShader(gl, source, type) {
+    const shader = gl.createShader(type);
+    gl.shaderSource(shader, source);
+    gl.compileShader(shader);
+    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
+        console.error('Error compiling shader:', gl.getShaderInfoLog(shader));
+        gl.deleteShader(shader);
+        return null;
+    }
+    return shader;
+}
+
+function createProgram(gl, vertexShaderSource, fragmentShaderSource) {
+    const vertexShader = compileShader(gl, vertexShaderSource, gl.VERTEX_SHADER);
+    const fragmentShader = compileShader(gl, fragmentShaderSource, gl.FRAGMENT_SHADER);
+    const program = gl.createProgram();
+    gl.attachShader(program, vertexShader);
+    gl.attachShader(program, fragmentShader);
+    gl.linkProgram(program);
+    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
+        console.error('Error linking program:', gl.getProgramInfoLog(program));
+        gl.deleteProgram(program);
+        return null;
+    }
+    return program;
+}
+
+function resizeCanvas() {
+    const canvas = document.getElementById('canvas');
+    canvas.width = window.innerWidth;
+    canvas.height = window.innerHeight;
+    gl.viewport(0, 0, canvas.width, canvas.height);
+}
+
+function init() {
+    const canvas = document.getElementById('nebula-canvas');
+    gl = canvas.getContext('webgl');
+
+    if (!gl) {
+        console.error('WebGL not supported');
+        return;
+    }
+
+    program = createProgram(gl, vertexShaderSource, fragmentShaderSource);
+    if (!program) {
+        return;
+    }
+
+    gl.useProgram(program);
+
+    buffer = gl.createBuffer();
+    gl.bindBuffer(gl.ARRAY_BUFFER, buffer);
+    gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([-1, -1, -1, 3, 3, -1]), gl.STATIC_DRAW);
+
+    const positionAttrib = gl.getAttribLocation(program, 'position');
+    gl.enableVertexAttribArray(positionAttrib);
+    gl.vertexAttribPointer(positionAttrib, 2, gl.FLOAT, false, 0, 0);
+
+    gl.uniform1f(gl.getUniformLocation(program, 'eddy_scale'), 50.0);
+
+    resizeCanvas(); // Call resizeCanvas initially
+    window.addEventListener('resize', resizeCanvas); // Resize canvas when window is resized
+
+    let startTime = performance.now();
+    function animate() {
+        const time = (performance.now() - startTime) / 1000;
+        gl.uniform1f(gl.getUniformLocation(program, 'u_time'), time);
+
+        gl.clearColor(0, 0, 0, 1);
+        gl.clear(gl.COLOR_BUFFER_BIT);
+
+        gl.drawArrays(gl.TRIANGLES, 0, 3);
+
+        requestAnimationFrame(animate);
+    }
+    animate();
+}
+
+init();