playcanvas
Version:
Open-source WebGL/WebGPU 3D engine for the web
138 lines (137 loc) • 5.09 kB
JavaScript
import { Debug } from "../../core/debug.js";
import { BUFFER_GPUDYNAMIC, PRIMITIVE_POINTS } from "./constants.js";
import { VertexBuffer } from "./vertex-buffer.js";
import { DebugGraphics } from "./debug-graphics.js";
import { Shader } from "./shader.js";
import { ShaderDefinitionUtils } from "./shader-definition-utils.js";
class TransformFeedback {
/**
* Create a new TransformFeedback instance.
*
* @param {VertexBuffer} inputBuffer - The input vertex buffer.
* @param {VertexBuffer} [outputBuffer] - The optional output buffer.
* If not specified, a buffer with parameters matching the input buffer will be created.
* @param {number} [usage] - The optional usage type of the output vertex buffer. Can be:
*
* - {@link BUFFER_STATIC}
* - {@link BUFFER_DYNAMIC}
* - {@link BUFFER_STREAM}
* - {@link BUFFER_GPUDYNAMIC}
*
* Defaults to {@link BUFFER_GPUDYNAMIC} (which is recommended for continuous update).
*/
constructor(inputBuffer, outputBuffer, usage = BUFFER_GPUDYNAMIC) {
if (outputBuffer !== void 0 && !(outputBuffer instanceof VertexBuffer)) {
Debug.deprecated("Such a constructor that takes the second parameter usage is deprecated.");
usage = outputBuffer;
outputBuffer = void 0;
}
this.device = inputBuffer.device;
const gl = this.device.gl;
const outVB = outputBuffer ?? inputBuffer;
Debug.assert(
outVB.format.interleaved || outVB.format.elements.length <= 1,
outputBuffer ? "Output vertex buffer used by TransformFeedback needs to be interleaved." : "Input vertex buffer used by TransformFeedback needs to be interleaved."
);
if (usage === BUFFER_GPUDYNAMIC && outVB.usage !== usage) {
gl.bindBuffer(gl.ARRAY_BUFFER, outVB.impl.bufferId);
gl.bufferData(gl.ARRAY_BUFFER, outVB.storage, gl.DYNAMIC_COPY);
}
this._inputBuffer = inputBuffer;
this._destroyOutputBuffer = !outputBuffer;
this._outputBuffer = outputBuffer ?? new VertexBuffer(inputBuffer.device, inputBuffer.format, inputBuffer.numVertices, {
usage,
data: inputBuffer.storage
});
}
/**
* Creates a transform feedback ready vertex shader from code.
*
* @param {GraphicsDevice} graphicsDevice - The graphics device used by the renderer.
* @param {string} vertexCode - Vertex shader code. Should contain output variables starting with "out_" or feedbackVaryings.
* @param {string} name - Unique name for caching the shader.
* @param {string[]} [feedbackVaryings] - A list of shader output variable names that will be captured.
* @returns {Shader} A shader to use in the process() function.
*/
static createShader(graphicsDevice, vertexCode, name, feedbackVaryings) {
return new Shader(graphicsDevice, ShaderDefinitionUtils.createDefinition(graphicsDevice, {
name,
vertexCode,
feedbackVaryings,
useTransformFeedback: true,
fragmentCode: "void main(void) {gl_FragColor = vec4(0.0);}"
}));
}
/**
* Destroys the transform feedback helper object.
*/
destroy() {
if (this._destroyOutputBuffer) {
this._outputBuffer.destroy();
}
}
/**
* Runs the specified shader on the input buffer, writes results into the new buffer, then
* optionally swaps input/output.
*
* @param {Shader} shader - A vertex shader to run. Should be created with
* {@link TransformFeedback.createShader}.
* @param {boolean} [swap] - Swap input/output buffer data. Useful for continuous buffer
* processing. Default is true.
*/
process(shader, swap = true) {
const device = this.device;
DebugGraphics.pushGpuMarker(device, "TransformFeedback");
const oldRt = device.getRenderTarget();
device.setRenderTarget(null);
device.updateBegin();
device.setVertexBuffer(this._inputBuffer);
device.setRaster(false);
device.setTransformFeedbackBuffer(this._outputBuffer);
device.setShader(shader);
device.draw({
type: PRIMITIVE_POINTS,
base: 0,
baseVertex: 0,
count: this._inputBuffer.numVertices,
indexed: false
});
device.setTransformFeedbackBuffer(null);
device.setRaster(true);
device.updateEnd();
device.setRenderTarget(oldRt);
DebugGraphics.popGpuMarker(device);
if (swap) {
Debug.call(() => {
if (this._inputBuffer.format !== this._outputBuffer.format) {
Debug.warnOnce("Trying to swap buffers with different formats.");
}
});
let tmp = this._inputBuffer.impl.bufferId;
this._inputBuffer.impl.bufferId = this._outputBuffer.impl.bufferId;
this._outputBuffer.impl.bufferId = tmp;
tmp = this._inputBuffer.impl.vao;
this._inputBuffer.impl.vao = this._outputBuffer.impl.vao;
this._outputBuffer.impl.vao = tmp;
}
}
/**
* The current input buffer.
*
* @type {VertexBuffer}
*/
get inputBuffer() {
return this._inputBuffer;
}
/**
* The current output buffer.
*
* @type {VertexBuffer}
*/
get outputBuffer() {
return this._outputBuffer;
}
}
export {
TransformFeedback
};