我正在学习 WebGL 技术。不幸的是我遇到了一些错误。我想为直升机绘制 2D 两个形状。我在下面写了代码。我真正想做的是在称为 body 的形状上制作螺旋桨。
请注意,我尝试创建一个新缓冲区并绑定(bind)它,但仍然失败。我认为 stride 还没有被理解,但我想学习如何解决它,即使它很简单。
// Vertex shader
var _vertexShader = `
attribute vec4 _position;
void main() {
gl_Position = _position;
}
`
// Fragment shader
var _fragmentShader = `
precision mediump float;
void main() {
gl_FragColor = vec4(0.6, 0.8, 0.3, 1);
}
`
// Create shader
function createShader(gl, type, source) {
var shader = gl.createShader(type)
gl.shaderSource(shader, source)
gl.compileShader(shader)
var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS)
if (success) {
return shader
} else {
console.log(gl.getShaderInfoLog(shader))
gl.deleteShader(shader)
// return false
}
}
// Linking shader by program
function createProgram(gl, vertexShader, fragmentShader) {
var program = gl.createProgram()
gl.attachShader(program, vertexShader)
gl.attachShader(program, fragmentShader)
gl.linkProgram(program)
var success = gl.getProgramParameter(program, gl.LINK_STATUS)
if (success) {
return program
} else {
console.log(gl.getProgramInfoLog(program))
gl.deleteProgram(program)
// return false
}
}
function main() {
// Get a WebGL context.
var canvas = document.getElementById('canvas')
var gl = canvas.getContext('webgl2')
if (!gl) {
alert('Not support.')
return false
}
// Get the strings for our GLSL shaders.
var vertexShader = createShader(gl, gl.VERTEX_SHADER, _vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, _fragmentShader)
// Link the two shaders into a program.
var program = createProgram(gl, vertexShader, fragmentShader)
// Look up where the vertex data need to go.
var positionLoc = gl.getAttribLocation(program, '_position')
// Create a buffer and put the three 2d clip space points in it.
var body_positionBuf = gl.createBuffer()
// Bind it to ARRAY_BUFFER (think of it as ARRAY_BUFFER = body_positionBuf).
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
var body_positions = new Float32Array(
[
// Body triangle (Right)
-0.25, 0,
0.25, 0,
0, 0.5,
// Body triangle (Left)
-0.15, 0,
0.15, 0,
0.15, -0.25,
// Body square
-0.15, 0,
-0.15, -0.25,
0.15, -0.25,
]
)
var roter_positions = new Float32Array([
0.15, 0.1,
0.15, -0.1,
-0.15, 0.1,
-0.15, -0.1,
-0.15, 0.1,
0.15, 0.1,
])
gl.bufferData(gl.ARRAY_BUFFER, body_positions, gl.STATIC_DRAW)
// Code above this line is initialization code.
// Code below this line is rendering code.
// webglUtils.resizeCanvasToDisplaySize(gl.canvas)
// Tell WebGL how to convert from clip space to pixels.
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height)
// Clear the canvas.
gl.clearColor(0, 0, 0, 0)
gl.clear(gl.COLOR_BUFFER_BIT)
// Tell it to use our program (pair of shaders).
gl.useProgram(program)
// Turn on the attribute.
gl.enableVertexAttribArray(positionLoc)
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
// Tell the attribute how to get data out of body_positionBuf (ARRAY_BUFFER).
var size = 2
var type = gl.FLOAT
var normalize = false
var stride = 0
var offset = 0
gl.vertexAttribPointer(positionLoc, size, type, normalize, stride, offset)
// Draw.
var drawType = gl.TRIANGLES
var count = body_positions.length / 2
gl.drawArrays(drawType, offset, count)
}
main()
<canvas id="canvas" width="500" height="250"></canvas>
我该怎么办?我不知道.. 请帮助我谢谢。
最佳答案
在body_positions
中指定的所有顶点坐标的第一个覆盖在roter_positions
中指定的顶点。
改变顶点坐标:
var roter_positions = new Float32Array([
0.15, 0.6,
0.15, 0.4,
-0.15, 0.6,
-0.15, 0.4,
-0.15, 0.6,
0.15, 0.6,
])
注意,我建议使用模型矩阵来单独定义每个对象的位置和方向。但请先解决您的问题,然后再进行下一步。
如果你想使用 2 个缓冲区,那么你必须创建 2 个缓冲区对象并且你必须定义这两个对象的数据存储:
var body_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, body_positions, gl.STATIC_DRAW)
var roter_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, roter_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, roter_positions, gl.STATIC_DRAW)
最后,您可以通过 2 个单独的绘制调用在 2 个单独的缓冲区中绘制网格。您必须在每次绘制调用之前定义通用顶点属性数据数组:
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
gl.drawArrays(gl.TRIANGLES, 0, body_positions.length / 2)
gl.bindBuffer(gl.ARRAY_BUFFER, roter_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
gl.drawArrays(gl.TRIANGLES, 0, roter_positions.length / 2)
查看示例,我将更改应用于您的原始代码:
// Vertex shader
var _vertexShader = `
attribute vec4 _position;
void main() {
gl_Position = _position;
}
`
// Fragment shader
var _fragmentShader = `
precision mediump float;
void main() {
gl_FragColor = vec4(0.6, 0.8, 0.3, 1);
}
`
// Create shader
function createShader(gl, type, source) {
var shader = gl.createShader(type)
gl.shaderSource(shader, source)
gl.compileShader(shader)
var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS)
if (success) {
return shader
} else {
console.log(gl.getShaderInfoLog(shader))
gl.deleteShader(shader)
// return false
}
}
// Linking shader by program
function createProgram(gl, vertexShader, fragmentShader) {
var program = gl.createProgram()
gl.attachShader(program, vertexShader)
gl.attachShader(program, fragmentShader)
gl.linkProgram(program)
var success = gl.getProgramParameter(program, gl.LINK_STATUS)
if (success) {
return program
} else {
console.log(gl.getProgramInfoLog(program))
gl.deleteProgram(program)
// return false
}
}
function main() {
// Get a WebGL context.
var canvas = document.getElementById('canvas')
var gl = canvas.getContext('webgl2')
if (!gl) {
alert('Not support.')
return false
}
// Get the strings for our GLSL shaders.
var vertexShader = createShader(gl, gl.VERTEX_SHADER, _vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, _fragmentShader)
// Link the two shaders into a program.
var program = createProgram(gl, vertexShader, fragmentShader)
// Look up where the vertex data need to go.
var positionLoc = gl.getAttribLocation(program, '_position')
// Create a buffer and put the three 2d clip space points in it.
var body_positions = new Float32Array(
[
// Body triangle (Right)
-0.25, 0,
0.25, 0,
0, 0.5,
// Body triangle (Left)
-0.15, 0,
0.15, 0,
0.15, -0.25,
// Body square
-0.15, 0,
-0.15, -0.25,
0.15, -0.25,
]
)
var roter_positions = new Float32Array([
0.15, 0.6,
0.15, 0.4,
-0.15, 0.6,
-0.15, 0.4,
-0.15, 0.6,
0.15, 0.6,
])
var body_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, body_positions, gl.STATIC_DRAW)
var roter_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, roter_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, roter_positions, gl.STATIC_DRAW)
// webglUtils.resizeCanvasToDisplaySize(gl.canvas)
// Tell WebGL how to convert from clip space to pixels.
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height)
// Clear the canvas.
gl.clearColor(0, 0, 0, 0)
gl.clear(gl.COLOR_BUFFER_BIT)
// Tell it to use our program (pair of shaders).
gl.useProgram(program)
// Turn on the attribute.
gl.enableVertexAttribArray(positionLoc)
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, body_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
gl.drawArrays(gl.TRIANGLES, 0, body_positions.length / 2)
gl.bindBuffer(gl.ARRAY_BUFFER, roter_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
gl.drawArrays(gl.TRIANGLES, 0, roter_positions.length / 2)
}
main();
<canvas id="canvas" width="500" height="250"></canvas>
当然,您可以将 2 个数组添加到 1 个缓冲区。您必须创建一个带有数据存储的缓冲区,该缓冲区对于两个数组来说都足够大。通过gl.bufferData
将数据添加到缓冲区:
var body_bytes = body_positions.length * 4;
var roter_bytes = roter_positions.length * 4;
var common_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, common_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, body_bytes + roter_bytes, gl.STATIC_DRAW);
gl.bufferSubData(gl.ARRAY_BUFFER, 0, body_positions);
gl.bufferSubData(gl.ARRAY_BUFFER, body_bytes, roter_positions);
可以通过单个绘制调用绘制网格:
gl.bindBuffer(gl.ARRAY_BUFFER, common_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
var no_of_vertices = (body_positions.length + roter_positions.length) / 2
gl.drawArrays(gl.TRIANGLES, 0, no_of_vertices)
如果某些程序资源必须在绘制第二个网格之前更改(例如模型矩阵统一),那么这也可以通过 2 个绘制调用来完成:
gl.drawArrays(gl.TRIANGLES, 0, body_positions.length / 2)
// change resources here ...
gl.drawArrays(gl.TRIANGLES, body_positions.length / 2, roter_positions.length / 2)
根据问题中的原始代码查看示例:
// Vertex shader
var _vertexShader = `
attribute vec4 _position;
void main() {
gl_Position = _position;
}
`
// Fragment shader
var _fragmentShader = `
precision mediump float;
void main() {
gl_FragColor = vec4(0.6, 0.8, 0.3, 1);
}
`
// Create shader
function createShader(gl, type, source) {
var shader = gl.createShader(type)
gl.shaderSource(shader, source)
gl.compileShader(shader)
var success = gl.getShaderParameter(shader, gl.COMPILE_STATUS)
if (success) {
return shader
} else {
console.log(gl.getShaderInfoLog(shader))
gl.deleteShader(shader)
// return false
}
}
// Linking shader by program
function createProgram(gl, vertexShader, fragmentShader) {
var program = gl.createProgram()
gl.attachShader(program, vertexShader)
gl.attachShader(program, fragmentShader)
gl.linkProgram(program)
var success = gl.getProgramParameter(program, gl.LINK_STATUS)
if (success) {
return program
} else {
console.log(gl.getProgramInfoLog(program))
gl.deleteProgram(program)
// return false
}
}
function main() {
// Get a WebGL context.
var canvas = document.getElementById('canvas')
var gl = canvas.getContext('webgl2')
if (!gl) {
alert('Not support.')
return false
}
// Get the strings for our GLSL shaders.
var vertexShader = createShader(gl, gl.VERTEX_SHADER, _vertexShader)
var fragmentShader = createShader(gl, gl.FRAGMENT_SHADER, _fragmentShader)
// Link the two shaders into a program.
var program = createProgram(gl, vertexShader, fragmentShader)
// Look up where the vertex data need to go.
var positionLoc = gl.getAttribLocation(program, '_position')
// Create a buffer and put the three 2d clip space points in it.
var body_positions = new Float32Array(
[
// Body triangle (Right)
-0.25, 0,
0.25, 0,
0, 0.5,
// Body triangle (Left)
-0.15, 0,
0.15, 0,
0.15, -0.25,
// Body square
-0.15, 0,
-0.15, -0.25,
0.15, -0.25,
]
)
var roter_positions = new Float32Array([
0.15, 0.6,
0.15, 0.4,
-0.15, 0.6,
-0.15, 0.4,
-0.15, 0.6,
0.15, 0.6,
])
var body_bytes = body_positions.length * 4;
var roter_bytes = roter_positions.length * 4;
var common_positionBuf = gl.createBuffer()
gl.bindBuffer(gl.ARRAY_BUFFER, common_positionBuf)
gl.bufferData(gl.ARRAY_BUFFER, body_bytes + roter_bytes, gl.STATIC_DRAW);
gl.bufferSubData(gl.ARRAY_BUFFER, 0, body_positions);
gl.bufferSubData(gl.ARRAY_BUFFER, body_bytes, roter_positions);
// webglUtils.resizeCanvasToDisplaySize(gl.canvas)
// Tell WebGL how to convert from clip space to pixels.
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height)
// Clear the canvas.
gl.clearColor(0, 0, 0, 0)
gl.clear(gl.COLOR_BUFFER_BIT)
// Tell it to use our program (pair of shaders).
gl.useProgram(program)
// Turn on the attribute.
gl.enableVertexAttribArray(positionLoc)
// Bind the position buffer.
gl.bindBuffer(gl.ARRAY_BUFFER, common_positionBuf)
gl.vertexAttribPointer(positionLoc, 2, gl.FLOAT, false, 0, 0)
var no_of_vertices = (body_positions.length + roter_positions.length) / 2
gl.drawArrays(gl.TRIANGLES, 0, no_of_vertices)
}
main();
<canvas id="canvas" width="500" height="250"></canvas>
关于javascript - WebGL 2.0 错误 : glDrawArrays: attempt to access out of range vertices in attribute 0,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/53025098/