Javascript 多次调用DrawArray以保持渲染缓冲区
我正在尝试使用WebGL制作像赢得纸牌一样的动画。我编写了以下代码来绘制多张卡片Javascript 多次调用DrawArray以保持渲染缓冲区,javascript,glsl,webgl,Javascript,Glsl,Webgl,我正在尝试使用WebGL制作像赢得纸牌一样的动画。我编写了以下代码来绘制多张卡片 const canvas = document.createElement('canvas'); canvas.width = canvas.height = 400; document.body.appendChild(canvas); const gl = canvas.getContext('webgl'); const program = gl.createProgram(); const shaderS
const canvas = document.createElement('canvas');
canvas.width = canvas.height = 400;
document.body.appendChild(canvas);
const gl = canvas.getContext('webgl');
const program = gl.createProgram();
const shaderSources = {
VERTEX_SHADER: `
precision highp float;
attribute vec2 aCoord;
uniform float uOffset;
void main(void) {
gl_Position = vec4(aCoord + vec2(uOffset, 0.0), 0.0, 1.0);
}
`,
FRAGMENT_SHADER: `
precision highp float;
void main(void) {
gl_FragColor = vec4(1.0, 0.0, 0.0, 1.0);
}
`
}
for (let i in shaderSources) {
const shader = gl.createShader(gl[i]);
gl.shaderSource(shader, shaderSources[i]);
gl.compileShader(shader);
gl.attachShader(program, shader);
}
gl.linkProgram(program);
gl.useProgram(program);
const aCoordLocation = gl.getAttribLocation(program, 'aCoord');
const aCoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, aCoordBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array([
-0.75, -0.25, -0.25, -0.25, -0.25, 0.25,
-0.75, -0.25, -0.75, 0.25, -0.25, 0.25
]), gl.STATIC_DRAW);
gl.enableVertexAttribArray(aCoordLocation);
gl.bindBuffer(gl.ARRAY_BUFFER, aCoordBuffer);
gl.vertexAttribPointer(aCoordLocation, 2, gl.FLOAT, false, 0, 0);
在那之后,当我运行下面的代码时,两个红色的正方形如预期的那样被绘制出来
gl.uniform1f(gl.getUniformLocation(program, 'uOffset'), 0);
gl.drawArrays(gl.TRIANGLES, 0, 6);
gl.uniform1f(gl.getUniformLocation(program, 'uOffset'), 1);
gl.drawArrays(gl.TRIANGLES, 0, 6);
但是,如果一个图形由于动画而延迟,则只渲染一个正方形(第一个正方形消失)
当使用时差多次执行drawArray时,是否有办法离开渲染缓冲区?在
WebGLContextAttributes字典中设置PreservedDrawingBuffer:true
,作为第二个参数传递给getContext
请参见WebGLContextAttributes字典中的设置preserveDrawingBuffer:true
,作为第二个参数传递给getContext
看
gl.uniform1f(gl.getUniformLocation(program, 'uOffset'), 0);
gl.drawArrays(gl.TRIANGLES, 0, 6);
setTimeout(() => {
gl.uniform1f(gl.getUniformLocation(program, 'uOffset'), 1);
gl.drawArrays(gl.TRIANGLES, 0, 6);
});