我知道WebGL可以对你渲染到屏幕上的内容进行抗锯齿或多重采样,以避免出现硬边缘。但是当我使用帧缓冲时,它不再起作用,屏幕上出现了许多锯齿状的边缘。
如何使帧缓冲使用多重采样?
如何使帧缓冲使用多重采样?
canvas.getContext("webgl2", {antialias: false});
来初始化上下文。在此方法中使用抗锯齿将无法工作。Renderbuffer
对象和两个Framebuffer
对象,一个用于存储绘制内容,另一个用于处理后期的抗锯齿图形。 // Create and bind the framebuffer
const FRAMEBUFFER =
{
RENDERBUFFER: 0,
COLORBUFFER: 1
};
const fb =
[
gl.createFramebuffer(),
gl.createFramebuffer()
];
const colorRenderbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER,
colorRenderbuffer);
gl.renderbufferStorageMultisample(gl.RENDERBUFFER,
gl.getParameter(gl.MAX_SAMPLES),
gl.RGBA8,
targetTextureWidth,
targetTextureHeight);
gl.bindFramebuffer(gl.FRAMEBUFFER,
fb[FRAMEBUFFER.RENDERBUFFER]);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER,
gl.COLOR_ATTACHMENT0,
gl.RENDERBUFFER,
colorRenderbuffer);
gl.bindFramebuffer(gl.FRAMEBUFFER,
fb[FRAMEBUFFER.COLORBUFFER]);
gl.framebufferTexture2D(gl.FRAMEBUFFER,
gl.COLOR_ATTACHMENT0,
gl.TEXTURE_2D,
targetTexture, 0);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
在绘制纹理之前,将Framebuffer
设置为两个Framebuffer
对象中的第一个。
// render to our targetTexture by binding the framebuffer
gl.bindFramebuffer(gl.FRAMEBUFFER,
fb[FRAMEBUFFER.RENDERBUFFER]);
接下来进行纹理绘制,然后进行抗锯齿处理,这将需要第二个缓冲区。
// ... drawing code ...
//
// "blit" the cube into the color buffer, which adds antialiasing
gl.bindFramebuffer(gl.READ_FRAMEBUFFER,
fb[FRAMEBUFFER.RENDERBUFFER]);
gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER,
fb[FRAMEBUFFER.COLORBUFFER]);
gl.clearBufferfv(gl.COLOR, 0, [1.0, 1.0, 1.0, 1.0]);
gl.blitFramebuffer(0, 0, targetTextureWidth, targetTextureHeight,
0, 0, targetTextureWidth, targetTextureHeight,
gl.COLOR_BUFFER_BIT, gl.LINEAR);
// render the top layer to the framebuffer as well
gl.bindFramebuffer(gl.FRAMEBUFFER,
fb[FRAMEBUFFER.RENDERBUFFER]);
在将顶层绘制到缓冲区后,使用之前相同的抗锯齿方法,这次将DRAW_FRAMEBUFFER
设置为null
;这告诉它绘制到实际的画布。
// this time render to the default buffer, which is just canvas
gl.bindFramebuffer(gl.READ_FRAMEBUFFER,
fb[FRAMEBUFFER.RENDERBUFFER]);
gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, null);
gl.clearBufferfv(gl.COLOR, 0, [1.0, 1.0, 1.0, 1.0]);
gl.blitFramebuffer(0, 0, canvas.width, canvas.height,
0, 0, canvas.width, canvas.height,
gl.COLOR_BUFFER_BIT, gl.LINEAR);
这是最终产品:
"use strict";
var vertexShaderSource = `#version 300 es
// an attribute is an input (in) to a vertex shader.
// It will receive data from a buffer
in vec4 a_position;
in vec2 a_texcoord;
// A matrix to transform the positions by
uniform mat4 u_matrix;
// a varying to pass the texture coordinates to the fragment shader
out vec2 v_texcoord;
// all shaders have a main function
void main() {
// Multiply the position by the matrix.
gl_Position = u_matrix * a_position;
// Pass the texcoord to the fragment shader.
v_texcoord = a_texcoord;
}
`;
var fragmentShaderSource = `#version 300 es
precision mediump float;
// Passed in from the vertex shader.
in vec2 v_texcoord;
// The texture.
uniform sampler2D u_texture;
// we need to declare an output for the fragment shader
out vec4 outColor;
void main() {
outColor = texture(u_texture, v_texcoord);
}
`;
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
var canvas = document.getElementById("canvas");
var gl = canvas.getContext("webgl2", {
antialias: false
});
if (!gl) {
return;
}
// Use our boilerplate utils to compile the shaders and link into a program
var program = webglUtils.createProgramFromSources(gl, [vertexShaderSource, fragmentShaderSource]);
// look up where the vertex data needs to go.
var positionAttributeLocation = gl.getAttribLocation(program, "a_position");
var texcoordAttributeLocation = gl.getAttribLocation(program, "a_texcoord");
// look up uniform locations
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
var textureLocation = gl.getUniformLocation(program, "u_texture");
// Create a buffer
var positionBuffer = gl.createBuffer();
// Create a vertex array object (attribute state)
var vao = gl.createVertexArray();
// and make it the one we're currently working with
gl.bindVertexArray(vao);
// Turn on the attribute
gl.enableVertexAttribArray(positionAttributeLocation);
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Set Geometry.
setGeometry(gl);
// Tell the attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 3; // 3 components per iteration
var type = gl.FLOAT; // the data is 32bit floats
var normalize = false; // don't normalize the data
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next position
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
positionAttributeLocation, size, type, normalize, stride, offset);
// create the texcoord buffer, make it the current ARRAY_BUFFER
// and copy in the texcoord values
var texcoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
setTexcoords(gl);
// Turn on the attribute
gl.enableVertexAttribArray(texcoordAttributeLocation);
// Tell the attribute how to get data out of colorBuffer (ARRAY_BUFFER)
var size = 2; // 2 components per iteration
var type = gl.FLOAT; // the data is 32bit floating point values
var normalize = true; // convert from 0-255 to 0.0-1.0
var stride = 0; // 0 = move forward size * sizeof(type) each iteration to get the next color
var offset = 0; // start at the beginning of the buffer
gl.vertexAttribPointer(
texcoordAttributeLocation, size, type, normalize, stride, offset);
// Create a texture.
var texture = gl.createTexture();
// use texture unit 0
gl.activeTexture(gl.TEXTURE0 + 0);
// bind to the TEXTURE_2D bind point of texture unit 0
gl.bindTexture(gl.TEXTURE_2D, texture);
// fill texture with 3x2 pixels
{
const level = 0;
const internalFormat = gl.R8;
const width = 3;
const height = 2;
const border = 0;
const format = gl.RED;
const type = gl.UNSIGNED_BYTE;
const data = new Uint8Array([
128, 64, 128,
0, 192, 0,
]);
gl.pixelStorei(gl.UNPACK_ALIGNMENT, 1);
gl.texImage2D(gl.TEXTURE_2D, level, internalFormat, width, height, border,
format, type, data);
}
// set the filtering so we don't need mips
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
// Create a texture to render to
const targetTextureWidth = 512;
const targetTextureHeight = 512;
const targetTexture = gl.createTexture();
gl.bindTexture(gl.TEXTURE_2D, targetTexture);
{
// define size and format of level 0
const level = 0;
const internalFormat = gl.RGBA;
const border = 0;
const format = gl.RGBA;
const type = gl.UNSIGNED_BYTE;
const data = null;
gl.texImage2D(gl.TEXTURE_2D, level, internalFormat,
targetTextureWidth, targetTextureHeight, border,
format, type, data);
// set the filtering so we don't need mips
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE);
gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE);
}
// Create and bind the framebuffer
const FRAMEBUFFER = {
RENDERBUFFER: 0,
COLORBUFFER: 1
};
const fb = [gl.createFramebuffer(), gl.createFramebuffer()];
const colorRenderbuffer = gl.createRenderbuffer();
gl.bindRenderbuffer(gl.RENDERBUFFER, colorRenderbuffer);
gl.renderbufferStorageMultisample(gl.RENDERBUFFER, gl.getParameter(gl.MAX_SAMPLES), gl.RGBA8, targetTextureWidth, targetTextureHeight);
gl.bindFramebuffer(gl.FRAMEBUFFER, fb[FRAMEBUFFER.RENDERBUFFER]);
gl.framebufferRenderbuffer(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.RENDERBUFFER, colorRenderbuffer);
gl.bindFramebuffer(gl.FRAMEBUFFER, fb[FRAMEBUFFER.COLORBUFFER]);
gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, targetTexture, 0);
gl.bindFramebuffer(gl.FRAMEBUFFER, null);
function degToRad(d) {
return d * Math.PI / 180;
}
var fieldOfViewRadians = degToRad(60);
var modelXRotationRadians = degToRad(0);
var modelYRotationRadians = degToRad(0);
// Get the starting time.
var then = 0;
requestAnimationFrame(drawScene);
function drawCube(aspect) {
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Bind the attribute/buffer set we want.
gl.bindVertexArray(vao);
// Compute the projection matrix
var projectionMatrix =
m4.perspective(fieldOfViewRadians, aspect, 1, 2000);
var cameraPosition = [0, 0, 2];
var up = [0, 1, 0];
var target = [0, 0, 0];
// Compute the camera's matrix using look at.
var cameraMatrix = m4.lookAt(cameraPosition, target, up);
// Make a view matrix from the camera matrix.
var viewMatrix = m4.inverse(cameraMatrix);
var viewProjectionMatrix = m4.multiply(projectionMatrix, viewMatrix);
var matrix = m4.xRotate(viewProjectionMatrix, modelXRotationRadians);
matrix = m4.yRotate(matrix, modelYRotationRadians);
// Set the matrix.
gl.uniformMatrix4fv(matrixLocation, false, matrix);
// Tell the shader to use texture unit 0 for u_texture
gl.uniform1i(textureLocation, 0);
// Draw the geometry.
var primitiveType = gl.TRIANGLES;
var offset = 0;
var count = 6 * 6;
gl.drawArrays(primitiveType, offset, count);
}
// Draw the scene.
function drawScene(time) {
// convert to seconds
time *= 0.001;
// Subtract the previous time from the current time
var deltaTime = time - then;
// Remember the current time for the next frame.
then = time;
// Animate the rotation
modelYRotationRadians += -0.7 * deltaTime;
modelXRotationRadians += -0.4 * deltaTime;
//webglUtils.resizeCanvasToDisplaySize(gl.canvas);
gl.enable(gl.CULL_FACE);
gl.enable(gl.DEPTH_TEST);
{
// render to our targetTexture by binding the framebuffer
gl.bindFramebuffer(gl.FRAMEBUFFER, fb[FRAMEBUFFER.RENDERBUFFER]);
// render cube with our 3x2 texture
gl.bindTexture(gl.TEXTURE_2D, texture);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, targetTextureWidth, targetTextureHeight);
// Clear the canvas AND the depth buffer.
gl.clearColor(0, 0, 1, 1); // clear to blue
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
const aspect = targetTextureWidth / targetTextureHeight;
drawCube(aspect);
// "blit" the cube into the color buffer, which adds antialiasing
gl.bindFramebuffer(gl.READ_FRAMEBUFFER, fb[FRAMEBUFFER.RENDERBUFFER]);
gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, fb[FRAMEBUFFER.COLORBUFFER]);
gl.clearBufferfv(gl.COLOR, 0, [1.0, 1.0, 1.0, 1.0]);
gl.blitFramebuffer(0, 0, targetTextureWidth, targetTextureHeight,
0, 0, targetTextureWidth, targetTextureHeight,
gl.COLOR_BUFFER_BIT, gl.LINEAR);
}
{
// render the top layer to the frame buffer as well
gl.bindFramebuffer(gl.FRAMEBUFFER, fb[FRAMEBUFFER.RENDERBUFFER]);
// render the cube with the texture we just rendered to
gl.bindTexture(gl.TEXTURE_2D, targetTexture);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, targetTextureWidth, targetTextureHeight);
// Clear the canvas AND the depth buffer.
gl.clearColor(0.105, 0.105, 0.105, 1); // clear to black
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
const aspect = 1;
drawCube(aspect);
// this time render to the default buffer, which is just canvas
gl.bindFramebuffer(gl.READ_FRAMEBUFFER, fb[FRAMEBUFFER.RENDERBUFFER]);
gl.bindFramebuffer(gl.DRAW_FRAMEBUFFER, null);
gl.clearBufferfv(gl.COLOR, 0, [1.0, 1.0, 1.0, 1.0]);
gl.blitFramebuffer(0, 0, canvas.width, canvas.height,
0, 0, canvas.width, canvas.height,
gl.COLOR_BUFFER_BIT, gl.LINEAR);
}
requestAnimationFrame(drawScene);
}
}
// Fill the buffer with the values that define a cube.
function setGeometry(gl) {
var positions = new Float32Array(
[-0.5, -0.5, -0.5, -0.5, 0.5, -0.5,
0.5, -0.5, -0.5, -0.5, 0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
-0.5, -0.5, 0.5,
0.5, -0.5, 0.5, -0.5, 0.5, 0.5, -0.5, 0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, 0.5,
-0.5, 0.5, -0.5, -0.5, 0.5, 0.5,
0.5, 0.5, -0.5, -0.5, 0.5, 0.5,
0.5, 0.5, 0.5,
0.5, 0.5, -0.5,
-0.5, -0.5, -0.5,
0.5, -0.5, -0.5, -0.5, -0.5, 0.5, -0.5, -0.5, 0.5,
0.5, -0.5, -0.5,
0.5, -0.5, 0.5,
-0.5, -0.5, -0.5, -0.5, -0.5, 0.5, -0.5, 0.5, -0.5, -0.5, -0.5, 0.5, -0.5, 0.5, 0.5, -0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, -0.5,
0.5, 0.5, 0.5,
]);
gl.bufferData(gl.ARRAY_BUFFER, positions, gl.STATIC_DRAW);
}
// Fill the buffer with texture coordinates the cube.
function setTexcoords(gl) {
gl.bufferData(
gl.ARRAY_BUFFER,
new Float32Array(
[
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
0, 0,
0, 1,
1, 0,
0, 1,
1, 1,
1, 0,
0, 0,
0, 1,
1, 0,
1, 0,
0, 1,
1, 1,
]),
gl.STATIC_DRAW);
}
main();
html
{
background-color: #1b1b1b;
}
<canvas id="canvas" width="512" height="512"></canvas>
<!--
for most samples webgl-utils only provides shader compiling/linking and
canvas resizing because why clutter the examples with code that's the same in every sample.
See http://webglfundamentals.org/webgl/lessons/webgl-boilerplate.html
and http://webglfundamentals.org/webgl/lessons/webgl-resizing-the-canvas.html
for webgl-utils, m3, m4, and webgl-lessons-ui.
-->
<script src="https://webgl2fundamentals.org/webgl/resources/webgl-utils.js"></script>
<script src="https://webgl2fundamentals.org/webgl/resources/m4.js"></script>
WebGL1不支持帧缓冲的多重采样,因此在这种情况下,您的选项是将渲染分辨率提高并在渲染到画布时进行降采样和/或运行一些后处理效果来执行抗锯齿。
WebGL2支持帧缓冲的多重采样。您可以调用renderbufferStorageMultisample
创建一个多重采样的渲染缓冲区,并且您可以调用blitFramebuffer
将其解析到画布中。
renderbufferStorageMultisample
不支持gl.RGBA4
,尽管它被列为有效格式。我真的希望找到一种发现配置无效的方法。 - zoran404webgl-lint
添加到您的项目中,它会装饰 WebGL 上下文以添加大量错误检查。 - Mark K Cowangl.RGBA4
,但是gl.RGBA4
的问题在于它与 Canvas 的帧缓冲格式不匹配,我看到错误信息:[.WebGL-0x134003b4600] GL_INVALID_OPERATION: Attempt to blit from a multisampled framebuffer and the bounds or format of the color buffer don't match with the draw framebuffer.
- Bacher