【发布时间】：2017-06-19 22:56:26
【问题描述】：
使用 WebGL 2，我们现在可以使用统一缓冲区对象。
它们看起来是个好主意，不必将通用制服附加到每个程序（例如每个被渲染对象通用的投影和视图矩阵）。
我创建了一个辅助类，每次我想绑定一个统一的缓冲区对象时都会调用它。
class UniformBuffer {
constructor(gl, data, boundLocation = 0) {
this.boundLocation = boundLocation;
this.data = new Float32Array(data);
this.buffer = gl.createBuffer();
gl.bindBuffer(gl.UNIFORM_BUFFER, this.buffer);
gl.bufferData(gl.UNIFORM_BUFFER, this.data, gl.DYNAMIC_DRAW);
gl.bindBuffer(gl.UNIFORM_BUFFER, null);
gl.bindBufferBase(gl.UNIFORM_BUFFER, this.boundLocation, this.buffer);
}
update(gl, data, offset = 0) {
this.data.set(data, offset);
gl.bindBuffer(gl.UNIFORM_BUFFER, this.buffer);
gl.bufferSubData(gl.UNIFORM_BUFFER, 0, this.data, 0, null);
gl.bindBuffer(gl.UNIFORM_BUFFER, null);
gl.bindBufferBase(gl.UNIFORM_BUFFER, this.boundLocation, this.buffer);
}
};
是否像这样创建统一缓冲区的想法
const perScene = new UniformBuffer(gl, [
...vec4.create(),
...vec4.create(),
], 0); // and bind it to bind location 0?
const perObject = new UniformBuffer(gl, [
...vec4.create(),
], 1); // and bind it to bind location 1?
在我的渲染循环中，然后我通过调用更新“perScene”制服
perScene.update(gl, [
...vec4.fromValues(1, 0, 0, 1),
], 4); // giving an offset to update only the 2nd color.
然后我将查看场景中的所有对象，我的想法是像这样更新 perObject 统一缓冲区
for (let i = 0; i < objects.length; i++) {
perObject.update(gl, [
...vec4.fromValues(0, 0, 1, 1),
]);
}
我说vec4 只是为了使示例更简单，但其想法是在 perScene 上拥有矩阵（投影和视图），在 perObject 上拥有（对象和法线矩阵）。
在我的着色器中，我将它们声明为
uniform perScene {
vec4 color1;
vec4 color2;
};
uniform perModel {
vec4 color3;
};
我在这里有一个工作的 sn-p
class UniformBuffer {
constructor(gl, data, boundLocation = 0) {
this.boundLocation = boundLocation;
this.data = new Float32Array(data);
this.buffer = gl.createBuffer();
gl.bindBuffer(gl.UNIFORM_BUFFER, this.buffer);
gl.bufferData(gl.UNIFORM_BUFFER, this.data, gl.DYNAMIC_DRAW);
gl.bindBuffer(gl.UNIFORM_BUFFER, null);
gl.bindBufferBase(gl.UNIFORM_BUFFER, this.boundLocation, this.buffer);
}
update(gl, data, offset = 0) {
this.data.set(data, offset);
gl.bindBuffer(gl.UNIFORM_BUFFER, this.buffer);
gl.bufferSubData(gl.UNIFORM_BUFFER, 0, this.data, 0, null);
gl.bindBuffer(gl.UNIFORM_BUFFER, null);
gl.bindBufferBase(gl.UNIFORM_BUFFER, this.boundLocation, this.buffer);
}
};
const vertex = `#version 300 es
uniform perScene {
vec4 color1;
vec4 color2;
};
uniform perModel {
vec4 color3;
};
in vec3 a_position;
out vec3 v_color;
void main() {
gl_Position = vec4(a_position, 1.0);
v_color = color1.rgb + color2.rgb; // WORKS
// v_color = color1.rgb + color2.rgb + color3.rgb; // DOESNT WORK
}
`;
const fragment = `#version 300 es
precision highp float;
precision highp int;
in vec3 v_color;
out vec4 outColor;
void main() {
outColor = vec4(v_color, 1.0);
}
`;
const geometry = {
positions: [-0.5, -0.5, 0, -0.5, 0.5, 0, 0.5, -0.5, 0, 0.5, 0.5, 0],
indices: [0, 2, 1, 1, 2, 3],
};
const renderList = [];
// STEP 1 (create canvas)
var canvas = document.getElementById("canvas");
var gl = canvas.getContext("webgl2");
if (!gl) {
console.log('no webgl2 buddy');
}
// STEP 2 (create program)
const v = gl.createShader(gl.VERTEX_SHADER);
gl.shaderSource(v, vertex);
gl.compileShader(v);
const f = gl.createShader(gl.FRAGMENT_SHADER);
gl.shaderSource(f, fragment);
gl.compileShader(f);
const program = gl.createProgram();
gl.attachShader(program, v);
gl.attachShader(program, f);
gl.linkProgram(program);
// STEP 3 (create VAO)
const positionAttributeLocation = gl.getAttribLocation(program, 'a_position');
const colorUniformLocation = gl.getUniformLocation(program, 'color');
const positionsBuffer = gl.createBuffer();
const indicesBuffer = gl.createBuffer();
const vao = gl.createVertexArray();
gl.bindVertexArray(vao);
// position & indices
gl.enableVertexAttribArray(positionAttributeLocation);
gl.bindBuffer(gl.ARRAY_BUFFER, positionsBuffer);
gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(geometry.positions), gl.STATIC_DRAW);
gl.vertexAttribPointer(positionAttributeLocation, 3, gl.FLOAT, false, 0, 0);
gl.bindBuffer(gl.ARRAY_BUFFER, null);
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, indicesBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, new Uint16Array(geometry.indices), gl.STATIC_DRAW);
// STEP 4 (create UBO)
// bound to location 0
const perScene = new UniformBuffer(gl, [
...vec4.create(), // color 1
...vec4.create(), // color 2
], 0);
// bound to location 1 ?
const perModel = new UniformBuffer(gl, [
...vec4.create(), // color 3
], 3);
// STEP 5 (add instances)
for (let i = 0; i < 1; i++) {
renderList.push({
id: i,
vao: vao,
program: program,
color: [0, 1, 1],
});
}
// STEP 6 (draw)
gl.clearColor(0, 0, 0, 0);
gl.enable(gl.DEPTH_TEST);
gl.viewport(0, 0, canvas.width, canvas.height);
perScene.update(gl, [
...vec4.fromValues(1, 0, 0, 1),
...vec4.fromValues(0, 1, 0, 1),
]);
for (let i = 0; i < renderList.length; i++) {
const current = renderList[i];
gl.useProgram(current.program);
gl.bindVertexArray(current.vao);
// update perObject
perModel.update(gl, [
...vec4.fromValues(0, 0, 1, 1),
]);
gl.drawElements(gl.TRIANGLES, geometry.indices.length, gl.UNSIGNED_SHORT, 0);
// unbind
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, null);
}
console.log('compiled!');canvas {
background-color: black;
}<canvas id="canvas"></canvas>
<script src="https://cdnjs.cloudflare.com/ajax/libs/gl-matrix/2.3.2/gl-matrix-min.js"></script>我不应该看到一个白色方块，因为所有颜色加起来都会产生vec4(1.0, 1.0, 1.0, 1.0)？ （jsfiddle 第 41 行）
我做错了什么？ 谢谢
【问题讨论】：