webgl - WebGL：无法显示两个纹理
问题描述
我正在尝试使用纹理天空盒（使用立方体贴图）渲染纹理立方体（使用顶点、索引和 tex 坐标），但不知何故我总是收到以下错误消息：
WebGL：INVALID_OPERATION：bindTexture：纹理不能用于多个目标
我有两个纹理并且可能错误地使用 gl.activeTexture 但我无法弄清楚。
如您所见，纹理立方体在天空盒似乎被绘制在其上之前短暂闪烁。
使用此代码的临时（24 小时）网站：http: //priceless-dijkstra-4bf2a5.netlify.com/
有任何想法吗？
<!-- Licensed under a BSD license. See license.html for license -->
<!-- src: https://webglfundamentals.org/ -->
<!DOCTYPE html>
<html>
<head>
<meta charset = "utf-8">
<meta name = "viewport" content = "width=device-width, initial-scale=1.0, user-scalable=yes">
<title> WebGL - Textures - Data Texture 3 x2</title>
<link type = "text/css" href = "./webgl-tutorials.css" rel = "stylesheet" />
</head>
<body>
<div class = "description">
A 3 x2 texture <br />
</div>
<canvas id = "canvas"></canvas>
</body>
<!-- vertex shader -->
<script id = "3d-vertex-shader" type = "x-shader/x-vertex">
attribute vec4 a_position;
attribute vec2 a_texcoord;
uniform mat4 u_matrix;
varying vec2 v_texcoord;
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;
}
</script>
<!-- fragment shader -->
<script id = "3d-fragment-shader" type = "x-shader/x-fragment">
precision mediump float;
// Passed in from the vertex shader.
varying vec2 v_texcoord;
// The texture.
uniform sampler2D u_texture;
void main()
{
gl_FragColor = texture2D(u_texture, v_texcoord);
}
</script>
<!--skybox vertex shader-->
<script id="skybox-vertex-shader" type="x-shader/x-vertex">
attribute vec4 a_position;
varying vec4 v_position;
void main()
{
v_position = a_position;
gl_Position = a_position;
}
</script>
<!--skybox fragment shader-->
<script id="skybox-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
uniform samplerCube u_skybox;
uniform mat4 u_viewDirectionProjectionInverse;
varying vec4 v_position;
void main()
{
vec4 t = u_viewDirectionProjectionInverse * v_position;
gl_FragColor = textureCube(u_skybox, normalize(t.xyz / t.w));
}
</script>
<script src = "./webgl-utils.js"></script>
<script src = "./m4.js"></script>
<script src = "./primitives.js"></script>
<script type = "module">
"use strict";
function main()
{
// Get A WebGL context
/** @type {HTMLCanvasElement} */
var canvas = document.getElementById("canvas");
var gl = canvas.getContext("webgl");
if (!gl)
{
return;
}
// setup GLSL program
var program = webglUtils.createProgramFromScripts(gl, ["3d-vertex-shader", "3d-fragment-shader"]);
// look up where the vertex data needs to go.
var positionLocation = gl.getAttribLocation(program, "a_position");
var texcoordLocation = gl.getAttribLocation(program, "a_texcoord");
// lookup uniforms
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
var textureLocation = gl.getUniformLocation(program, "u_texture");
//create program for skybox
const skyboxProgramInfo = webglUtils.createProgramInfo(gl, ["skybox-vertex-shader", "skybox-fragment-shader"]);
var sb_textureLocation = gl.getUniformLocation(skyboxProgramInfo.program, "u_skybox");
// create buffers and fill with vertex data
const cubeBufferInfo = primitives.createCubeBufferInfo(gl, 1);
const quadBufferInfo = primitives.createXYQuadBufferInfo(gl);
// Create a texture.
const sb_texture = gl.createTexture();
gl.activeTexture(gl.TEXTURE0 + 1);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, sb_texture);
const faceInfos =
[
{ target: gl.TEXTURE_CUBE_MAP_POSITIVE_X, url: './pos-x.jpg', },
{ target: gl.TEXTURE_CUBE_MAP_NEGATIVE_X, url: './neg-x.jpg', },
{ target: gl.TEXTURE_CUBE_MAP_POSITIVE_Y, url: './pos-y.jpg', },
{ target: gl.TEXTURE_CUBE_MAP_NEGATIVE_Y, url: './neg-y.jpg', },
{ target: gl.TEXTURE_CUBE_MAP_POSITIVE_Z, url: './pos-z.jpg', },
{ target: gl.TEXTURE_CUBE_MAP_NEGATIVE_Z, url: './neg-z.jpg', },
];
faceInfos.forEach((faceInfo) =>
{
const {target, url} = faceInfo;
// Upload the canvas to the cubemap face.
const level = 0;
const internalFormat = gl.RGBA;
const width = 512;
const height = 512;
const format = gl.RGBA;
const type = gl.UNSIGNED_BYTE;
// setup each face so it's immediately renderable
gl.texImage2D(target, level, internalFormat, width, height, 0, format, type, null);
// Asynchronously load an image
const image = new Image();
image.src = url;
image.addEventListener('load', function()
{
// Now that the image has loaded make copy it to the skybox texture.
gl.activeTexture(gl.TEXTURE0 + 1);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, sb_texture);
gl.texImage2D(target, level, internalFormat, format, type, image);
gl.generateMipmap(gl.TEXTURE_CUBE_MAP);
});
});
gl.generateMipmap(gl.TEXTURE_CUBE_MAP);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
// Create a buffer for positions
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Put the positions in the buffer
setGeometry(gl);
// Create a buffer for positions
var indexBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
// Put the positions in the buffer
setIndices(gl);
// provide texture coordinates for the rectangle.
var texcoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Set Texcoords.
setTexcoords(gl);
// Create a texture.
var texture = gl.createTexture();
//void gl.bindTexture(target, texture);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, texture);
// fill texture with 3x2 pixels
const level = 0;
const internalFormat = gl.RGB;
const width = 2;
const height = 2;
const border = 0;
const format = gl.RGB;
const type = gl.UNSIGNED_BYTE;
const data = new Uint8Array
([
255, 0, 0, 0, 255, 0,
0, 0, 255, 128, 128, 128,
]);
const alignment = 1;
gl.pixelStorei(gl.UNPACK_ALIGNMENT, alignment);
gl.texImage2D(gl.TEXTURE_2D, level, internalFormat, width, height, border, format, type, data);
// set the filtering so we don't need mips and it's not filtered
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);
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);
// 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;
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.enable(gl.CULL_FACE);
gl.enable(gl.DEPTH_TEST);
// Animate the rotation
modelYRotationRadians += -0.7 * deltaTime;
modelXRotationRadians += -0.4 * deltaTime;
// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Turn on the position attribute
gl.enableVertexAttribArray(positionLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the position 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( positionLocation, size, type, normalize, stride, offset);
// Turn on the teccord attribute
gl.enableVertexAttribArray(texcoordLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Tell the position attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 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( texcoordLocation, size, type, normalize, stride, offset);
// Compute the projection matrix
var aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
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.
gl.drawElements(gl.TRIANGLES, 36, gl.UNSIGNED_SHORT, 0);
// Skybox: we only care about direction so remove the translation
var viewDirectionMatrix = m4.copy(viewMatrix);
viewDirectionMatrix[12] = 0;
viewDirectionMatrix[13] = 0;
viewDirectionMatrix[14] = 0;
var viewDirectionProjectionMatrix = m4.multiply(projectionMatrix, viewDirectionMatrix);
var viewDirectionProjectionInverseMatrix = m4.inverse(viewDirectionProjectionMatrix);
// draw the skybox
gl.useProgram(skyboxProgramInfo.program);
webglUtils.setBuffersAndAttributes(gl, skyboxProgramInfo, quadBufferInfo);
webglUtils.setUniforms(skyboxProgramInfo, {
u_viewDirectionProjectionInverse: viewDirectionProjectionInverseMatrix,
u_skybox: texture,
});
// Tell the shader to use texture unit 0 for u_texture
gl.uniform1i(sb_textureLocation, 1);
webglUtils.drawBufferInfo(gl, quadBufferInfo);
requestAnimationFrame(drawScene);
}
}
// Fill the buffer with the values that define a cube.
function setGeometry(gl)
{
var positions = new Float32Array
([
// Front face
-0.5, -0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, 0.5,
-0.5, 0.5, 0.5,
// Back face
-0.5, -0.5, -0.5,
-0.5, 0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
// Top face
-0.5, 0.5, -0.5,
-0.5, 0.5, 0.5,
0.5, 0.5, 0.5,
0.5, 0.5, -0.5,
// Bottom face
-0.5, -0.5, -0.5,
0.5, -0.5, -0.5,
0.5, -0.5, 0.5,
-0.5, -0.5, 0.5,
// Right face
0.5, -0.5, -0.5,
0.5, 0.5, -0.5,
0.5, 0.5, 0.5,
0.5, -0.5, 0.5,
// Left face
-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
([
// Front
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Back
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Top
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Bottom
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Right
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Left
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
]),
gl.STATIC_DRAW);
}
// Fill the buffer with vertex indices
function setIndices(gl)
{
var indices = new Uint16Array
([
0, 1, 2, 0, 2, 3, // front
4, 5, 6, 4, 6, 7, // back
8, 9, 10, 8, 10, 11, // top
12, 13, 14, 12, 14, 15, // bottom
16, 17, 18, 16, 18, 19, // right
20, 21, 22, 20, 22, 23, // left
]);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
}
main();
</script>
</html>
解决方案
为了让代码正常工作，我必须做 3 件事
在绘制立方体之前绑定 indexBuffer
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);不要在底部设置纹理
gl.uniform1i(sb_textureLocation, 1);对天空盒使用正确的纹理
webglUtils.setUniforms(skyboxProgramInfo, { u_viewDirectionProjectionInverse: viewDirectionProjectionInverseMatrix, u_skybox: texture, // wrong--------------- u_skybox: sb_texture, // right--------------- });
一些东西。
webglUtils.setBuffersAndAttributes设置绘制给定对象所需的所有缓冲区和属性。在这种情况下，这意味着当你打电话时webglUtils.setBuffersAndAttributes(gl, skyboxProgramInfo, quadBufferInfo);天空盒所需的索引绑定到 ELEMENT_ARRAY_BUFFER。这意味着第二次通过
drawSceneindexBuffer 不会绑定到您的多维数据集。webglUtils.setUniforms为您管理活动的纹理单元。这意味着这个电话webglUtils.setUniforms(skyboxProgramInfo, { u_viewDirectionProjectionInverse: viewDirectionProjectionInverseMatrix, u_skybox: texture, });设置
texture为活动单元 0。setUniforms刚从 0 开始，并为使用的每个纹理计数。texture错误的纹理，u_skybox这就是您收到错误的原因。上面的代码转换为gl.uniformMatrix4fv(u_viewDirectionProjectionInverseLocation, false, viewDirectionProjectionInverseMatrix); gl.activeTexture(gl.TEXTURE0 + 0); gl.bindTexture(gl.TEXTURE_CUBE_MAP, texture); gl.uniform1i(u_skyboxLocation, 0);
纹理单元通常只在绘制时才关心，而不是在初始化时。它们是一组全局位置，用于为下一次绘制调用附加纹理。在每次抽奖调用之间，您都应该设置它们，但是对于您将要进行的抽奖来说，这是必需的。
For each texture the shaders used by the next draw call need
gl.activeTexture(gl.TEXTURE0 + n);
gl.bindTexture(targetTypeForTexture, texture);
gl.uniform1i(n);
另请参阅https://webglfundamentals.org/webgl/lessons/webgl-texture-units.html
"use strict";
function main() {
// Get A WebGL context
/** @type {HTMLCanvasElement} */
var canvas = document.getElementById("canvas");
var gl = canvas.getContext("webgl");
if (!gl) {
return;
}
// setup GLSL program
var program = webglUtils.createProgramFromScripts(gl, ["3d-vertex-shader", "3d-fragment-shader"]);
// look up where the vertex data needs to go.
var positionLocation = gl.getAttribLocation(program, "a_position");
var texcoordLocation = gl.getAttribLocation(program, "a_texcoord");
// lookup uniforms
var matrixLocation = gl.getUniformLocation(program, "u_matrix");
var textureLocation = gl.getUniformLocation(program, "u_texture");
//create program for skybox
const skyboxProgramInfo = webglUtils.createProgramInfo(gl, ["skybox-vertex-shader", "skybox-fragment-shader"]);
var sb_textureLocation = gl.getUniformLocation(skyboxProgramInfo.program, "u_skybox");
// create buffers and fill with vertex data
const cubeBufferInfo = primitives.createCubeBufferInfo(gl, 1);
const quadBufferInfo = primitives.createXYQuadBufferInfo(gl);
// Create a texture.
const sb_texture = gl.createTexture();
gl.activeTexture(gl.TEXTURE0 + 1);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, sb_texture);
const faceInfos = [
{
target: gl.TEXTURE_CUBE_MAP_POSITIVE_X,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/pos-x.jpg',
},
{
target: gl.TEXTURE_CUBE_MAP_NEGATIVE_X,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/neg-x.jpg',
},
{
target: gl.TEXTURE_CUBE_MAP_POSITIVE_Y,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/pos-y.jpg',
},
{
target: gl.TEXTURE_CUBE_MAP_NEGATIVE_Y,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/neg-y.jpg',
},
{
target: gl.TEXTURE_CUBE_MAP_POSITIVE_Z,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/pos-z.jpg',
},
{
target: gl.TEXTURE_CUBE_MAP_NEGATIVE_Z,
url: 'https://webglfundamentals.org/webgl/resources/images/computer-history-museum/neg-z.jpg',
},
];
faceInfos.forEach((faceInfo) => {
const {
target,
url
} = faceInfo;
// Upload the canvas to the cubemap face.
const level = 0;
const internalFormat = gl.RGBA;
const width = 512;
const height = 512;
const format = gl.RGBA;
const type = gl.UNSIGNED_BYTE;
// setup each face so it's immediately renderable
gl.texImage2D(target, level, internalFormat, width, height, 0, format, type, null);
// Asynchronously load an image
const image = new Image();
image.src = url;
image.crossOrigin = 'anonymous';
image.addEventListener('load', function() {
// Now that the image has loaded make copy it to the skybox texture.
gl.activeTexture(gl.TEXTURE0 + 1);
gl.bindTexture(gl.TEXTURE_CUBE_MAP, sb_texture);
gl.texImage2D(target, level, internalFormat, format, type, image);
gl.generateMipmap(gl.TEXTURE_CUBE_MAP);
});
});
gl.generateMipmap(gl.TEXTURE_CUBE_MAP);
gl.texParameteri(gl.TEXTURE_CUBE_MAP, gl.TEXTURE_MIN_FILTER, gl.LINEAR_MIPMAP_LINEAR);
// Create a buffer for positions
var positionBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Put the positions in the buffer
setGeometry(gl);
// Create a buffer for positions
var indexBuffer = gl.createBuffer();
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = positionBuffer)
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
// Put the positions in the buffer
setIndices(gl);
// provide texture coordinates for the rectangle.
var texcoordBuffer = gl.createBuffer();
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Set Texcoords.
setTexcoords(gl);
// Create a texture.
var texture = gl.createTexture();
//void gl.bindTexture(target, texture);
gl.activeTexture(gl.TEXTURE0);
gl.bindTexture(gl.TEXTURE_2D, texture);
// fill texture with 3x2 pixels
const level = 0;
const internalFormat = gl.RGB;
const width = 2;
const height = 2;
const border = 0;
const format = gl.RGB;
const type = gl.UNSIGNED_BYTE;
const data = new Uint8Array([
255, 0, 0, 0, 255, 0,
0, 0, 255, 128, 128, 128,
]);
const alignment = 1;
gl.pixelStorei(gl.UNPACK_ALIGNMENT, alignment);
gl.texImage2D(gl.TEXTURE_2D, level, internalFormat, width, height, border, format, type, data);
// set the filtering so we don't need mips and it's not filtered
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);
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);
// 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;
webglUtils.resizeCanvasToDisplaySize(gl.canvas);
// Tell WebGL how to convert from clip space to pixels
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
gl.enable(gl.CULL_FACE);
gl.enable(gl.DEPTH_TEST);
// Animate the rotation
modelYRotationRadians += -0.7 * deltaTime;
modelXRotationRadians += -0.4 * deltaTime;
// Clear the canvas AND the depth buffer.
gl.clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT);
// Tell it to use our program (pair of shaders)
gl.useProgram(program);
// Turn on the position attribute
gl.enableVertexAttribArray(positionLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, positionBuffer);
// Tell the position 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(positionLocation, size, type, normalize, stride, offset);
// Turn on the teccord attribute
gl.enableVertexAttribArray(texcoordLocation);
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, texcoordBuffer);
// Tell the position attribute how to get data out of positionBuffer (ARRAY_BUFFER)
var size = 2; // 2 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(texcoordLocation, size, type, normalize, stride, offset);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indexBuffer);
// Compute the projection matrix
var aspect = gl.canvas.clientWidth / gl.canvas.clientHeight;
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.
gl.drawElements(gl.TRIANGLES, 36, gl.UNSIGNED_SHORT, 0);
// Skybox: we only care about direction so remove the translation
var viewDirectionMatrix = m4.copy(viewMatrix);
viewDirectionMatrix[12] = 0;
viewDirectionMatrix[13] = 0;
viewDirectionMatrix[14] = 0;
var viewDirectionProjectionMatrix = m4.multiply(projectionMatrix, viewDirectionMatrix);
var viewDirectionProjectionInverseMatrix = m4.inverse(viewDirectionProjectionMatrix);
// draw the skybox
gl.useProgram(skyboxProgramInfo.program);
webglUtils.setBuffersAndAttributes(gl, skyboxProgramInfo, quadBufferInfo);
webglUtils.setUniforms(skyboxProgramInfo, {
u_viewDirectionProjectionInverse: viewDirectionProjectionInverseMatrix,
u_skybox: sb_texture,
});
// Tell the shader to use texture unit 0 for u_texture
webglUtils.drawBufferInfo(gl, quadBufferInfo);
requestAnimationFrame(drawScene);
}
}
// Fill the buffer with the values that define a cube.
function setGeometry(gl) {
var positions = new Float32Array([
// Front face
-0.5, -0.5, 0.5,
0.5, -0.5, 0.5,
0.5, 0.5, 0.5, -0.5, 0.5, 0.5,
// Back face
-0.5, -0.5, -0.5, -0.5, 0.5, -0.5,
0.5, 0.5, -0.5,
0.5, -0.5, -0.5,
// Top face
-0.5, 0.5, -0.5, -0.5, 0.5, 0.5,
0.5, 0.5, 0.5,
0.5, 0.5, -0.5,
// Bottom face
-0.5, -0.5, -0.5,
0.5, -0.5, -0.5,
0.5, -0.5, 0.5, -0.5, -0.5, 0.5,
// Right face
0.5, -0.5, -0.5,
0.5, 0.5, -0.5,
0.5, 0.5, 0.5,
0.5, -0.5, 0.5,
// Left face
-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([
// Front
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Back
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Top
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Bottom
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Right
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
// Left
0.0, 0.0,
1.0, 0.0,
1.0, 1.0,
0.0, 1.0,
]),
gl.STATIC_DRAW);
}
// Fill the buffer with vertex indices
function setIndices(gl) {
var indices = new Uint16Array([
0, 1, 2, 0, 2, 3, // front
4, 5, 6, 4, 6, 7, // back
8, 9, 10, 8, 10, 11, // top
12, 13, 14, 12, 14, 15, // bottom
16, 17, 18, 16, 18, 19, // right
20, 21, 22, 20, 22, 23, // left
]);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, indices, gl.STATIC_DRAW);
}
main();<div class = "description">
A 3 x2 texture <br />
</div>
<canvas id = "canvas"></canvas>
<!-- vertex shader -->
<script id = "3d-vertex-shader" type = "x-shader/x-vertex">
attribute vec4 a_position;
attribute vec2 a_texcoord;
uniform mat4 u_matrix;
varying vec2 v_texcoord;
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;
}
</script>
<!-- fragment shader -->
<script id = "3d-fragment-shader" type = "x-shader/x-fragment">
precision mediump float;
// Passed in from the vertex shader.
varying vec2 v_texcoord;
// The texture.
uniform sampler2D u_texture;
void main()
{
gl_FragColor = texture2D(u_texture, v_texcoord);
}
</script>
<!--skybox vertex shader-->
<script id="skybox-vertex-shader" type="x-shader/x-vertex">
attribute vec4 a_position;
varying vec4 v_position;
void main()
{
v_position = a_position;
gl_Position = a_position;
}
</script>
<!--skybox fragment shader-->
<script id="skybox-fragment-shader" type="x-shader/x-fragment">
precision mediump float;
uniform samplerCube u_skybox;
uniform mat4 u_viewDirectionProjectionInverse;
varying vec4 v_position;
void main()
{
vec4 t = u_viewDirectionProjectionInverse * v_position;
gl_FragColor = textureCube(u_skybox, normalize(t.xyz / t.w));
}
</script>
<script src="https://webglfundamentals.org/webgl/resources/webgl-utils.js"></script>
<script src="https://webglfundamentals.org/webgl/resources/m4.js"></script>
<script src="https://webglfundamentals.org/webgl/resources/primitives.js"></script>推荐阅读
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