Efecto de transición de texto impresionante con HTML5 Canvas y JavaScript

Vista prévia

Descripción

Un efecto de transición de texto impresionante hecho por < a href = "https://codepen.io/whqet/" target = "_ blank" rel = "noopener" > whqet que anima una lista de palabras usando el elemento canvas de HTML5 y un poco de JavaScript. No se necesita CSS/CSS3.

Funcionamiento

Cree un elemento canvas vacío en la Página Web.

<canvas id="canvas" width="1000" height="800"></canvas>

El JavaScript. Reemplace la matriz de texto y Personalice las animaciones después de los comentarios en el JavaScript.

BLUR = false;

PULSATION = true;
PULSATION_PERIOD = 600;
PARTICLE_RADIUS = 4;

/* disable blur before using blink */

BLINK = false;

GLOBAL_PULSATION = false;

QUALITY = 2; /* 0 - 5 */

/* set false if you prefer rectangles */
ARC = true;

/* trembling + blur = fun */
TREMBLING = 0; /* 0 - infinity */

FANCY_FONT = "Arial";

BACKGROUND = "#000";

BLENDING = true;

/* if empty the text will be a random number */
var TEXT;
num = 0;
TEXTArray = ["CSS", "Demo","Text","Html","Java"];

QUALITY_TO_FONT_SIZE = [10, 12, 40, 50, 100, 350];
QUALITY_TO_SCALE = [20, 6, 4, 2, 0.9, 0.5];
QUALITY_TO_TEXT_POS = [10, 20, 60, 100, 370, 280];

window.onload = function () {


document.body.style.backgroundColor = BACKGROUND;



var canvas = document.getElementById("canvas");


var ctx = canvas.getContext("2d");



var W = canvas.width;


var H = canvas.height;



var tcanvas = document.createElement("canvas");


var tctx = tcanvas.getContext("2d");


tcanvas.width = W;


tcanvas.height = H;



total_area = W * H;


total_particles = 928;


single_particle_area = total_area / total_particles;


area_length = Math.sqrt(single_particle_area);



var particles = [];


for (var i = 1; i <= total_particles; i++) {




particles.push(new particle(i));


}



function particle(i) {




this.r = Math.round(Math.random() * 255|0);




this.g = Math.round(Math.random() * 255|0);




this.b = Math.round(Math.random() * 255|0);




this.alpha = 1;





this.x = (i * area_length) % W;




this.y = (i * area_length) / W * area_length;





/* randomize delta to make particles sparkling */




this.deltaOffset = Math.random() * PULSATION_PERIOD | 0;





this.radius = 0.1 + Math.random() * 2;


}

 	var positions = [];

	function new_positions() {





TEXT = TEXTArray[num];





if (num < TEXTArray.length - 1) {






num++;




} else {






num = 0;




}




//alert(TEXT);





tctx.fillStyle = "white";




tctx.fillRect(0, 0, W, H)




//tctx.fill();





tctx.font = "bold " + QUALITY_TO_FONT_SIZE[QUALITY] + "px " + FANCY_FONT;





//tctx.textAlign='center';//文本水平对齐方式




//tctx.textBaseline='middle';





//tctx.strokeStyle = "black";




tctx.fillStyle="#f00";




//tctx.strokeText(TEXT,30, 50);




tctx.fillText(TEXT,20, 60);





image_data = tctx.getImageData(0, 0, W, H);




pixels = image_data.data;




positions = [];




for (var i = 0; i < pixels.length; i = i + 2) {






if (pixels[i] != 255) {








position = {










x: (i / 2 % W | 0) * QUALITY_TO_SCALE[QUALITY] | 0,










y: (i / 2 / W | 0) * QUALITY_TO_SCALE[QUALITY] | 0








}








positions.push(position);






}




}





get_destinations();


}



function draw() {





var now = Date.now();





ctx.globalCompositeOperation = "source-over";





if (BLUR) ctx.globalAlpha = 0.1;




else if (!BLUR && !BLINK) ctx.globalAlpha = 1.0;





ctx.fillStyle = BACKGROUND;




ctx.fillRect(0, 0, W, H)





if (BLENDING) ctx.globalCompositeOperation = "lighter";





for (var i = 0; i < particles.length; i++) {







p = particles[i];







/* in lower qualities there is not enough full pixels for all of
them - dirty hack*/







if (isNaN(p.x)) continue







ctx.beginPath();






ctx.fillStyle = "rgb(" + p.r + ", " + p.g + ", " + p.b + ")";






ctx.fillStyle = "rgba(" + p.r + ", " + p.g + ", " + p.b + ", " + p.alpha + ")";







if (BLINK) ctx.globalAlpha = Math.sin(Math.PI * mod * 1.0);







if (PULSATION) { /* this would be 0 -> 1 */








var mod = ((GLOBAL_PULSATION ? 0 : p.deltaOffset) + now) % PULSATION_PERIOD / PULSATION_PERIOD;









/* lets make the value bouncing with sinus */








mod = Math.sin(mod * Math.PI);






} else var mod = 1;







var offset = TREMBLING ? TREMBLING * (-1 + Math.random() * 2) : 0;







var radius = PARTICLE_RADIUS * p.radius;







if (!ARC) {








ctx.fillRect(offset + p.x - mod * radius / 2 | 0, offset + p.y - mod * radius / 2 | 0, radius * mod,










radius * mod);






} else {








ctx.arc(offset + p.x | 0, offset + p.y | 0, radius * mod, Math.PI * 2, false);








ctx.fill();






}







p.x += (p.dx - p.x) / 10;






p.y += (p.dy - p.y) / 10;




}


}



function get_destinations() {




for (var i = 0; i < particles.length; i++) {






pa = particles[i];






particles[i].alpha = 1;






var distance = [];






nearest_position = 0;






if (positions.length) {








for (var n = 0; n < positions.length; n++) {










po = positions[n];










distance[n] = Math.sqrt((pa.x - po.x) * (pa.x - po.x) + (pa.y - po.y) * (pa.y - po.y));










if (n > 0) {












if (distance[n] <= distance[nearest_position]) {














nearest_position = n;












}










}








}








particles[i].dx = positions[nearest_position].x;








particles[i].dy = positions[nearest_position].y;








particles[i].distance = distance[nearest_position];









var po1 = positions[nearest_position];








for (var n = 0; n < positions.length; n++) {










var po2 = positions[n];










distance = Math.sqrt((po1.x - po2.x) * (po1.x - po2.x) + (po1.y - po2.y) * (po1.y - po2.y));










if (distance <= 5) {












positions.splice(n, 1);










}








}






} else {








//particles[i].alpha = 0;






}




}


}



function init() {




new_positions();




setInterval(draw, 30);




setInterval(new_positions, 2000);


}



init();
};