问题
I have seen that it is possible to create a sticky image effect on hover using three.js which inspired me with an idea of doing this effect over a video. I am using THREE.VideoTexture() in place of where an image was defined to create a background video. How can I set the video with the id video to the background of my canvas?
const videoSize = [1250, 1097];
const vertex = `
attribute vec2 uv;
attribute vec2 position;
varying vec2 vUv;
void main() {
vUv = uv;
gl_Position = vec4(position, 0, 1);
}
`;
const fragment = `
precision highp float;
precision highp int;
uniform sampler2D tWater;
uniform sampler2D tFlow;
uniform float uTime;
varying vec2 vUv;
uniform vec4 res;
void main() {
// R and G values are velocity in the x and y direction
// B value is the velocity length
vec3 flow = texture2D(tFlow, vUv).rgb;
vec2 uv = .5 * gl_FragCoord.xy / res.xy ;
vec2 myUV = (uv - vec2(0.5))*res.zw + vec2(0.5);
myUV -= flow.xy * (0.15 * 0.7);
vec2 myUV2 = (uv - vec2(0.5))*res.zw + vec2(0.5);
myUV2 -= flow.xy * (0.125 * 0.7);
vec2 myUV3 = (uv - vec2(0.5))*res.zw + vec2(0.5);
myUV3 -= flow.xy * (0.10 * 0.7);
vec3 tex = texture2D(tWater, myUV).rgb;
vec3 tex2 = texture2D(tWater, myUV2).rgb;
vec3 tex3 = texture2D(tWater, myUV3).rgb;
gl_FragColor = vec4(tex.r, tex2.g, tex3.b, 1.0);
}
`;
{
const renderer = new ogl.Renderer({ dpr: 2 });
const gl = renderer.gl;
document.body.appendChild(gl.canvas);
// Variable inputs to control flowmap
let aspect = 1;
const mouse = new ogl.Vec2(-1);
const velocity = new ogl.Vec2();
function resize() {
let a1, a2;
var videoAspect = video.width[1] / video.width[0];
if (window.innerHeight / window.innerWidth < videoAspect) {
a1 = 1;
a2 = window.innerHeight / window.innerWidth / videoAspect;
} else {
a1 = (window.innerWidth / window.innerHeight) * videoAspect;
a2 = 1;
}
mesh.program.uniforms.res.value = new ogl.Vec4(
window.innerWidth,
window.innerHeight,
a1,
a2
);
renderer.setSize(window.innerWidth, window.innerHeight);
aspect = window.innerWidth / window.innerHeight;
}
const flowmap = new ogl.Flowmap(gl, {
falloff: 1.0, // size of the stamp, percentage of the size
alpha: 0.7, // opacity of the stamp
dissipation: 0.95// affects the speed that the stamp fades. Closer to 1 is slower
});
// Triangle that includes -1 to 1 range for 'position', and 0 to 1 range for 'uv'.
const geometry = new ogl.Geometry(gl, {
position: {
size: 2,
data: new Float32Array([-1, -1, 3, -1, -1, 3])
},
uv: { size: 2, data: new Float32Array([0, 0, 2, 0, 0, 2]) }
});
const texture = new ogl.Texture(gl, {
minFilter: gl.LINEAR,
magFilter: gl.LINEAR
});
var video = document.getElementById( 'video' );
var videoTexture = new THREE.VideoTexture( video );
videoTexture.minFilter = THREE.LinearFilter;
videoTexture.magFilter = THREE.LinearFilter;
videoTexture.format = THREE.RGBFormat;
/*
const img = new Image();
img.onload = () => (texture.image = img);
img.crossOrigin = "Anonymous";
img.src = "./img/overlay.png";*/
video.onload = () => (texture.video = video);
video.crossOrigin = "Anonymous";
video.src = "./img/Morph.mp4";
let a1, a2;
var videoAspect = video.width[1] / video.width[0];
if (window.innerHeight / window.innerWidth < videoAspect) {
a1 = 1;
a2 = window.innerHeight / window.innerWidth / videoAspect;
} else {
a1 = (window.innerWidth / window.innerHeight) * videoAspect;
a2 = 1;
}
const program = new ogl.Program(gl, {
vertex,
fragment,
uniforms: {
uTime: { value: 0 },
tWater: { value: texture },
res: {
value: new ogl.Vec4(window.innerWidth, window.innerHeight, a1, a2)
},
video: { value: new ogl.Vec2(video.width[0], video.width[1]) },
// Note that the uniform is applied without using an object and value property
// This is because the class alternates this texture between two render targets
// and updates the value property after each render.
tFlow: flowmap.uniform
}
});
const mesh = new ogl.Mesh(gl, { geometry, program });
window.addEventListener("resize", resize, false);
resize();
// Create handlers to get mouse position and velocity
const isTouchCapable = "ontouchstart" in window;
if (isTouchCapable) {
window.addEventListener("touchstart", updateMouse, false);
window.addEventListener("touchmove", updateMouse, { passive: false });
} else {
window.addEventListener("mousemove", updateMouse, false);
}
let lastTime;
const lastMouse = new ogl.Vec2();
function updateMouse(e) {
e.preventDefault();
if (e.changedTouches && e.changedTouches.length) {
e.x = e.changedTouches[0].pageX;
e.y = e.changedTouches[0].pageY;
}
if (e.x === undefined) {
e.x = e.pageX;
e.y = e.pageY;
}
// Get mouse value in 0 to 1 range, with y flipped
mouse.set(e.x / gl.renderer.width, 1.0 - e.y / gl.renderer.height);
// Calculate velocity
if (!lastTime) {
// First frame
lastTime = performance.now();
lastMouse.set(e.x, e.y);
}
const deltaX = e.x - lastMouse.x;
const deltaY = e.y - lastMouse.y;
lastMouse.set(e.x, e.y);
let time = performance.now();
// Avoid dividing by 0
let delta = Math.max(10.4, time - lastTime);
lastTime = time;
velocity.x = deltaX / delta;
velocity.y = deltaY / delta;
// Flag update to prevent hanging velocity values when not moving
velocity.needsUpdate = true;
}
requestAnimationFrame(update);
function update(t) {
requestAnimationFrame(update);
// Reset velocity when mouse not moving
if (!velocity.needsUpdate) {
mouse.set(-1);
velocity.set(0);
}
velocity.needsUpdate = false;
// Update flowmap inputs
flowmap.aspect = aspect;
flowmap.mouse.copy(mouse);
// Ease velocity input, slower when fading out
flowmap.velocity.lerp(velocity, velocity.len ? 0.15 : 0.1);
flowmap.update();
program.uniforms.uTime.value = t * 0.01;
renderer.render({ scene: mesh });
}
}
来源：https://stackoverflow.com/questions/58834793/setting-background-video-in-canvas-using-video-texture-with-three-js-not-working