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社区首页 >专栏 >canvas霓虹爱心

canvas霓虹爱心

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我不是费圆
发布2021-12-30 18:25:08
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发布2021-12-30 18:25:08
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文章被收录于专栏:鲸鱼动画
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代码语言:javascript
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<!DOCTYPE html>
<html lang="en">
	<head>
		<meta charset="UTF-8">
		<title>canvas霓虹爱心</title>
		<style>
			body {
				background-color: #000;
				margin: 0;
				overflow: hidden;
				background-repeat: no-repeat;
			}
		</style>
	</head>
	<body>
		<canvas id="canvas" width="1400" height="600"></canvas>
		<script>
			var canvas = document.getElementById("canvas");
			canvas.width = window.innerWidth;
			canvas.height = window.innerHeight;
			// Initialize the GL context
			var gl = canvas.getContext('webgl');
			if (!gl) {
				console.error("Unable to initialize WebGL.");
			}
			//Time
			var time = 0.0;
			//************** Shader sources **************
			var vertexSource = `
	attribute vec2 position;
	void main() {
		gl_Position = vec4(position, 0.0, 1.0);
	}
	`;
			var fragmentSource = `
	precision highp float;
	
	uniform float width;
	uniform float height;
	vec2 resolution = vec2(width, height);
	
	uniform float time;
	
	#define POINT_COUNT 8
	
	vec2 points[POINT_COUNT];
	const float speed = -0.5;
	const float len = 0.25;
	float intensity = 1.3;
	float radius = 0.008;
	
	//https://www.shadertoy.com/view/MlKcDD
	//Signed distance to a quadratic bezier
	float sdBezier(vec2 pos, vec2 A, vec2 B, vec2 C){    
		vec2 a = B - A;
		vec2 b = A - 2.0*B + C;
		vec2 c = a * 2.0;
		vec2 d = A - pos;
	
		float kk = 1.0 / dot(b,b);
		float kx = kk * dot(a,b);
		float ky = kk * (2.0*dot(a,a)+dot(d,b)) / 3.0;
		float kz = kk * dot(d,a);      
	
		float res = 0.0;
	
		float p = ky - kx*kx;
		float p3 = p*p*p;
		float q = kx*(2.0*kx*kx - 3.0*ky) + kz;
		float h = q*q + 4.0*p3;
	
		if(h >= 0.0){ 
			h = sqrt(h);
			vec2 x = (vec2(h, -h) - q) / 2.0;
			vec2 uv = sign(x)*pow(abs(x), vec2(1.0/3.0));
			float t = uv.x + uv.y - kx;
			t = clamp( t, 0.0, 1.0 );
	
			// 1 root
			vec2 qos = d + (c + b*t)*t;
			res = length(qos);
		}else{
			float z = sqrt(-p);
			float v = acos( q/(p*z*2.0) ) / 3.0;
			float m = cos(v);
			float n = sin(v)*1.732050808;
			vec3 t = vec3(m + m, -n - m, n - m) * z - kx;
			t = clamp( t, 0.0, 1.0 );
	
			// 3 roots
			vec2 qos = d + (c + b*t.x)*t.x;
			float dis = dot(qos,qos);
	        
			res = dis;
	
			qos = d + (c + b*t.y)*t.y;
			dis = dot(qos,qos);
			res = min(res,dis);
			
			qos = d + (c + b*t.z)*t.z;
			dis = dot(qos,qos);
			res = min(res,dis);
	
			res = sqrt( res );
		}
	    
		return res;
	}
	
	
	//http://mathworld.wolfram.com/HeartCurve.html
	vec2 getHeartPosition(float t){
		return vec2(16.0 * sin(t) * sin(t) * sin(t),
								-(13.0 * cos(t) - 5.0 * cos(2.0*t)
								- 2.0 * cos(3.0*t) - cos(4.0*t)));
	}
	
	//https://www.shadertoy.com/view/3s3GDn
	float getGlow(float dist, float radius, float intensity){
		return pow(radius/dist, intensity);
	}
	
	float getSegment(float t, vec2 pos, float offset, float scale){
		for(int i = 0; i < POINT_COUNT; i++){
			points[i] = getHeartPosition(offset + float(i)*len + fract(speed * t) * 6.28);
		}
	    
		vec2 c = (points[0] + points[1]) / 2.0;
		vec2 c_prev;
		float dist = 10000.0;
	    
		for(int i = 0; i < POINT_COUNT-1; i++){
			//https://tinyurl.com/y2htbwkm
			c_prev = c;
			c = (points[i] + points[i+1]) / 2.0;
			dist = min(dist, sdBezier(pos, scale * c_prev, scale * points[i], scale * c));
		}
		return max(0.0, dist);
	}
	
	void main(){
		vec2 uv = gl_FragCoord.xy/resolution.xy;
		float widthHeightRatio = resolution.x/resolution.y;
		vec2 centre = vec2(0.5, 0.5);
		vec2 pos = centre - uv;
		pos.y /= widthHeightRatio;
		//Shift upwards to centre heart
		pos.y += 0.02;
		float scale = 0.000015 * height;
		
		float t = time;
	    
		//Get first segment
	  float dist = getSegment(t, pos, 0.0, scale);
	  float glow = getGlow(dist, radius, intensity);
	  
	  vec3 col = vec3(0.0);
	
		//White core
	  col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
	  //Pink glow
	  col += glow * vec3(1.0,0.05,0.3);
	  
	  //Get second segment
	  dist = getSegment(t, pos, 3.4, scale);
	  glow = getGlow(dist, radius, intensity);
	  
	  //White core
	  col += 10.0*vec3(smoothstep(0.003, 0.001, dist));
	  //Blue glow
	  col += glow * vec3(0.1,0.4,1.0);
	        
		//Tone mapping
		col = 1.0 - exp(-col);
	
		//Gamma
		col = pow(col, vec3(0.4545));
	
		//Output to screen
	 	gl_FragColor = vec4(col,1.0);
	}
	`;

			//************** Utility functions **************

			window.addEventListener('resize', onWindowResize, false);

			function onWindowResize() {
				canvas.width = window.innerWidth;
				canvas.height = window.innerHeight;
				gl.viewport(0, 0, canvas.width, canvas.height);
				gl.uniform1f(widthHandle, window.innerWidth);
				gl.uniform1f(heightHandle, window.innerHeight);
			}


			//Compile shader and combine with source
			function compileShader(shaderSource, shaderType) {
				var shader = gl.createShader(shaderType);
				gl.shaderSource(shader, shaderSource);
				gl.compileShader(shader);
				if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
					throw "Shader compile failed with: " + gl.getShaderInfoLog(shader);
				}
				return shader;
			}

			//From https://codepen.io/jlfwong/pen/GqmroZ
			//Utility to complain loudly if we fail to find the attribute/uniform
			function getAttribLocation(program, name) {
				var attributeLocation = gl.getAttribLocation(program, name);
				if (attributeLocation === -1) {
					throw 'Cannot find attribute ' + name + '.';
				}
				return attributeLocation;
			}

			function getUniformLocation(program, name) {
				var attributeLocation = gl.getUniformLocation(program, name);
				if (attributeLocation === -1) {
					throw 'Cannot find uniform ' + name + '.';
				}
				return attributeLocation;
			}

			//************** Create shaders **************

			//Create vertex and fragment shaders
			var vertexShader = compileShader(vertexSource, gl.VERTEX_SHADER);
			var fragmentShader = compileShader(fragmentSource, gl.FRAGMENT_SHADER);

			//Create shader programs
			var program = gl.createProgram();
			gl.attachShader(program, vertexShader);
			gl.attachShader(program, fragmentShader);
			gl.linkProgram(program);

			gl.useProgram(program);

			//Set up rectangle covering entire canvas 
			var vertexData = new Float32Array([
				-1.0, 1.0, // top left
				-1.0, -1.0, // bottom left
				1.0, 1.0, // top right
				1.0, -1.0, // bottom right
			]);

			//Create vertex buffer
			var vertexDataBuffer = gl.createBuffer();
			gl.bindBuffer(gl.ARRAY_BUFFER, vertexDataBuffer);
			gl.bufferData(gl.ARRAY_BUFFER, vertexData, gl.STATIC_DRAW);

			// Layout of our data in the vertex buffer
			var positionHandle = getAttribLocation(program, 'position');

			gl.enableVertexAttribArray(positionHandle);
			gl.vertexAttribPointer(positionHandle,
				2, // position is a vec2 (2 values per component)
				gl.FLOAT, // each component is a float
				false, // don't normalize values
				2 * 4, // two 4 byte float components per vertex (32 bit float is 4 bytes)
				0 // how many bytes inside the buffer to start from
			);

			//Set uniform handle
			var timeHandle = getUniformLocation(program, 'time');
			var widthHandle = getUniformLocation(program, 'width');
			var heightHandle = getUniformLocation(program, 'height');

			gl.uniform1f(widthHandle, window.innerWidth);
			gl.uniform1f(heightHandle, window.innerHeight);

			var lastFrame = Date.now();
			var thisFrame;

			function draw() {

				//Update time
				thisFrame = Date.now();
				time += (thisFrame - lastFrame) / 1000;
				lastFrame = thisFrame;

				//Send uniforms to program
				gl.uniform1f(timeHandle, time);
				//Draw a triangle strip connecting vertices 0-4
				gl.drawArrays(gl.TRIANGLE_STRIP, 0, 4);

				requestAnimationFrame(draw);
			}

			draw();
		</script>
	</body>
</html>
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原始发表:2021/10/24 ,如有侵权请联系 cloudcommunity@tencent.com 删除

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