/
GlyphRenderer.ts
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/
GlyphRenderer.ts
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/**
* Copyright (c) 2018 The xterm.js authors. All rights reserved.
* @license MIT
*/
import { createProgram, PROJECTION_MATRIX } from './WebglUtils';
import { IWebGL2RenderingContext, IWebGLVertexArrayObject, IRenderModel } from './Types';
import { fill } from 'common/TypedArrayUtils';
import { NULL_CELL_CODE } from 'common/buffer/Constants';
import { Terminal } from 'xterm';
import { IColorSet } from 'browser/Types';
import { IRasterizedGlyph, IRenderDimensions, ITextureAtlas } from 'browser/renderer/shared/Types';
import { Disposable, toDisposable } from 'common/Lifecycle';
import { throwIfFalsy } from 'browser/renderer/shared/RendererUtils';
interface IVertices {
attributes: Float32Array;
/**
* These buffers are the ones used to bind to WebGL, the reason there are
* multiple is to allow double buffering to work as you cannot modify the
* buffer while it's being used by the GPU. Having multiple lets us start
* working on the next frame.
*/
attributesBuffers: Float32Array[];
count: number;
}
const enum VertexAttribLocations {
UNIT_QUAD = 0,
CELL_POSITION = 1,
OFFSET = 2,
SIZE = 3,
TEXCOORD = 4,
TEXSIZE = 5
}
const vertexShaderSource = `#version 300 es
layout (location = ${VertexAttribLocations.UNIT_QUAD}) in vec2 a_unitquad;
layout (location = ${VertexAttribLocations.CELL_POSITION}) in vec2 a_cellpos;
layout (location = ${VertexAttribLocations.OFFSET}) in vec2 a_offset;
layout (location = ${VertexAttribLocations.SIZE}) in vec2 a_size;
layout (location = ${VertexAttribLocations.TEXCOORD}) in vec2 a_texcoord;
layout (location = ${VertexAttribLocations.TEXSIZE}) in vec2 a_texsize;
uniform mat4 u_projection;
uniform vec2 u_resolution;
out vec2 v_texcoord;
void main() {
vec2 zeroToOne = (a_offset / u_resolution) + a_cellpos + (a_unitquad * a_size);
gl_Position = u_projection * vec4(zeroToOne, 0.0, 1.0);
v_texcoord = a_texcoord + a_unitquad * a_texsize;
}`;
const fragmentShaderSource = `#version 300 es
precision lowp float;
in vec2 v_texcoord;
uniform sampler2D u_texture;
out vec4 outColor;
void main() {
outColor = texture(u_texture, v_texcoord);
}`;
const INDICES_PER_CELL = 10;
const BYTES_PER_CELL = INDICES_PER_CELL * Float32Array.BYTES_PER_ELEMENT;
const CELL_POSITION_INDICES = 2;
// Work variables to avoid garbage collection
let $i = 0;
let $glyph: IRasterizedGlyph | undefined = undefined;
let $leftCellPadding = 0;
let $clippedPixels = 0;
export class GlyphRenderer extends Disposable {
private _atlas: ITextureAtlas | undefined;
private _program: WebGLProgram;
private _vertexArrayObject: IWebGLVertexArrayObject;
private _projectionLocation: WebGLUniformLocation;
private _resolutionLocation: WebGLUniformLocation;
private _textureLocation: WebGLUniformLocation;
private _atlasTexture: WebGLTexture;
private _attributesBuffer: WebGLBuffer;
private _activeBuffer: number = 0;
private _vertices: IVertices = {
count: 0,
attributes: new Float32Array(0),
attributesBuffers: [
new Float32Array(0),
new Float32Array(0)
]
};
constructor(
private _terminal: Terminal,
private _gl: IWebGL2RenderingContext,
private _dimensions: IRenderDimensions
) {
super();
const gl = this._gl;
this._program = throwIfFalsy(createProgram(gl, vertexShaderSource, fragmentShaderSource));
this.register(toDisposable(() => gl.deleteProgram(this._program)));
// Uniform locations
this._projectionLocation = throwIfFalsy(gl.getUniformLocation(this._program, 'u_projection'));
this._resolutionLocation = throwIfFalsy(gl.getUniformLocation(this._program, 'u_resolution'));
this._textureLocation = throwIfFalsy(gl.getUniformLocation(this._program, 'u_texture'));
// Create and set the vertex array object
this._vertexArrayObject = gl.createVertexArray();
gl.bindVertexArray(this._vertexArrayObject);
// Setup a_unitquad, this defines the 4 vertices of a rectangle
const unitQuadVertices = new Float32Array([0, 0, 1, 0, 0, 1, 1, 1]);
const unitQuadVerticesBuffer = gl.createBuffer();
this.register(toDisposable(() => gl.deleteBuffer(unitQuadVerticesBuffer)));
gl.bindBuffer(gl.ARRAY_BUFFER, unitQuadVerticesBuffer);
gl.bufferData(gl.ARRAY_BUFFER, unitQuadVertices, gl.STATIC_DRAW);
gl.enableVertexAttribArray(VertexAttribLocations.UNIT_QUAD);
gl.vertexAttribPointer(VertexAttribLocations.UNIT_QUAD, 2, this._gl.FLOAT, false, 0, 0);
// Setup the unit quad element array buffer, this points to indices in
// unitQuadVertices to allow is to draw 2 triangles from the vertices
const unitQuadElementIndices = new Uint8Array([0, 1, 3, 0, 2, 3]);
const elementIndicesBuffer = gl.createBuffer();
this.register(toDisposable(() => gl.deleteBuffer(elementIndicesBuffer)));
gl.bindBuffer(gl.ELEMENT_ARRAY_BUFFER, elementIndicesBuffer);
gl.bufferData(gl.ELEMENT_ARRAY_BUFFER, unitQuadElementIndices, gl.STATIC_DRAW);
// Setup attributes
this._attributesBuffer = throwIfFalsy(gl.createBuffer());
this.register(toDisposable(() => gl.deleteBuffer(this._attributesBuffer)));
gl.bindBuffer(gl.ARRAY_BUFFER, this._attributesBuffer);
gl.enableVertexAttribArray(VertexAttribLocations.OFFSET);
gl.vertexAttribPointer(VertexAttribLocations.OFFSET, 2, gl.FLOAT, false, BYTES_PER_CELL, 0);
gl.vertexAttribDivisor(VertexAttribLocations.OFFSET, 1);
gl.enableVertexAttribArray(VertexAttribLocations.SIZE);
gl.vertexAttribPointer(VertexAttribLocations.SIZE, 2, gl.FLOAT, false, BYTES_PER_CELL, 2 * Float32Array.BYTES_PER_ELEMENT);
gl.vertexAttribDivisor(VertexAttribLocations.SIZE, 1);
gl.enableVertexAttribArray(VertexAttribLocations.TEXCOORD);
gl.vertexAttribPointer(VertexAttribLocations.TEXCOORD, 2, gl.FLOAT, false, BYTES_PER_CELL, 4 * Float32Array.BYTES_PER_ELEMENT);
gl.vertexAttribDivisor(VertexAttribLocations.TEXCOORD, 1);
gl.enableVertexAttribArray(VertexAttribLocations.TEXSIZE);
gl.vertexAttribPointer(VertexAttribLocations.TEXSIZE, 2, gl.FLOAT, false, BYTES_PER_CELL, 6 * Float32Array.BYTES_PER_ELEMENT);
gl.vertexAttribDivisor(VertexAttribLocations.TEXSIZE, 1);
gl.enableVertexAttribArray(VertexAttribLocations.CELL_POSITION);
gl.vertexAttribPointer(VertexAttribLocations.CELL_POSITION, 2, gl.FLOAT, false, BYTES_PER_CELL, 8 * Float32Array.BYTES_PER_ELEMENT);
gl.vertexAttribDivisor(VertexAttribLocations.CELL_POSITION, 1);
// Setup empty texture atlas
this._atlasTexture = throwIfFalsy(gl.createTexture());
this.register(toDisposable(() => gl.deleteTexture(this._atlasTexture)));
gl.bindTexture(gl.TEXTURE_2D, this._atlasTexture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, 1, 1, 0, gl.RGBA, gl.UNSIGNED_BYTE, new Uint8Array([0, 0, 255, 255]));
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);
// Allow drawing of transparent texture
gl.enable(gl.BLEND);
gl.blendFunc(gl.SRC_ALPHA, gl.ONE_MINUS_SRC_ALPHA);
// Set viewport
this.onResize();
}
public beginFrame(): boolean {
return this._atlas ? this._atlas.beginFrame() : true;
}
public updateCell(x: number, y: number, code: number, bg: number, fg: number, ext: number, chars: string, lastBg: number): void {
// Since this function is called for every cell (`rows*cols`), it must be very optimized. It
// should not instantiate any variables unless a new glyph is drawn to the cache where the
// slight slowdown is acceptable for the developer ergonomics provided as it's a once of for
// each glyph.
this._updateCell(this._vertices.attributes, x, y, code, bg, fg, ext, chars, lastBg);
}
private _updateCell(array: Float32Array, x: number, y: number, code: number | undefined, bg: number, fg: number, ext: number, chars: string, lastBg: number): void {
$i = (y * this._terminal.cols + x) * INDICES_PER_CELL;
// Exit early if this is a null character, allow space character to continue as it may have
// underline/strikethrough styles
if (code === NULL_CELL_CODE || code === undefined/* This is used for the right side of wide chars */) {
fill(array, 0, $i, $i + INDICES_PER_CELL - 1 - CELL_POSITION_INDICES);
return;
}
if (!this._atlas) {
return;
}
// Get the glyph
if (chars && chars.length > 1) {
$glyph = this._atlas.getRasterizedGlyphCombinedChar(chars, bg, fg, ext);
} else {
$glyph = this._atlas.getRasterizedGlyph(code, bg, fg, ext);
}
$leftCellPadding = Math.floor((this._dimensions.scaledCellWidth - this._dimensions.scaledCharWidth) / 2);
if (bg !== lastBg && $glyph.offset.x > $leftCellPadding) {
$clippedPixels = $glyph.offset.x - $leftCellPadding;
// a_origin
array[$i ] = -($glyph.offset.x - $clippedPixels) + this._dimensions.scaledCharLeft;
array[$i + 1] = -$glyph.offset.y + this._dimensions.scaledCharTop;
// a_size
array[$i + 2] = ($glyph.size.x - $clippedPixels) / this._dimensions.scaledCanvasWidth;
array[$i + 3] = $glyph.size.y / this._dimensions.scaledCanvasHeight;
// a_texcoord
array[$i + 4] = $glyph.texturePositionClipSpace.x + $clippedPixels / this._atlas.cacheCanvas.width;
array[$i + 5] = $glyph.texturePositionClipSpace.y;
// a_texsize
array[$i + 6] = $glyph.sizeClipSpace.x - $clippedPixels / this._atlas.cacheCanvas.width;
array[$i + 7] = $glyph.sizeClipSpace.y;
} else {
// a_origin
array[$i ] = -$glyph.offset.x + this._dimensions.scaledCharLeft;
array[$i + 1] = -$glyph.offset.y + this._dimensions.scaledCharTop;
// a_size
array[$i + 2] = $glyph.size.x / this._dimensions.scaledCanvasWidth;
array[$i + 3] = $glyph.size.y / this._dimensions.scaledCanvasHeight;
// a_texcoord
array[$i + 4] = $glyph.texturePositionClipSpace.x;
array[$i + 5] = $glyph.texturePositionClipSpace.y;
// a_texsize
array[$i + 6] = $glyph.sizeClipSpace.x;
array[$i + 7] = $glyph.sizeClipSpace.y;
}
// a_cellpos only changes on resize
}
public clear(): void {
const terminal = this._terminal;
const newCount = terminal.cols * terminal.rows * INDICES_PER_CELL;
// Clear vertices
if (this._vertices.count !== newCount) {
this._vertices.attributes = new Float32Array(newCount);
} else {
this._vertices.attributes.fill(0);
}
for (let i = 0; i < this._vertices.attributesBuffers.length; i++) {
if (this._vertices.count !== newCount) {
this._vertices.attributesBuffers[i] = new Float32Array(newCount);
} else {
this._vertices.attributesBuffers[i].fill(0);
}
}
this._vertices.count = newCount;
let i = 0;
for (let y = 0; y < terminal.rows; y++) {
for (let x = 0; x < terminal.cols; x++) {
this._vertices.attributes[i + 8] = x / terminal.cols;
this._vertices.attributes[i + 9] = y / terminal.rows;
i += INDICES_PER_CELL;
}
}
}
public onResize(): void {
const gl = this._gl;
gl.viewport(0, 0, gl.canvas.width, gl.canvas.height);
this.clear();
}
public render(renderModel: IRenderModel): void {
if (!this._atlas) {
return;
}
const gl = this._gl;
gl.useProgram(this._program);
gl.bindVertexArray(this._vertexArrayObject);
// Alternate buffers each frame as the active buffer gets locked while it's in use by the GPU
this._activeBuffer = (this._activeBuffer + 1) % 2;
const activeBuffer = this._vertices.attributesBuffers[this._activeBuffer];
// Copy data for each cell of each line up to its line length (the last non-whitespace cell)
// from the attributes buffer into activeBuffer, which is the one that gets bound to the GPU.
// The reasons for this are as follows:
// - So the active buffer can be alternated so we don't get blocked on rendering finishing
// - To copy either the normal attributes buffer or the selection attributes buffer when there
// is a selection
// - So we don't send vertices for all the line-ending whitespace to the GPU
let bufferLength = 0;
for (let y = 0; y < renderModel.lineLengths.length; y++) {
const si = y * this._terminal.cols * INDICES_PER_CELL;
const sub = this._vertices.attributes.subarray(si, si + renderModel.lineLengths[y] * INDICES_PER_CELL);
activeBuffer.set(sub, bufferLength);
bufferLength += sub.length;
}
// Bind the attributes buffer
gl.bindBuffer(gl.ARRAY_BUFFER, this._attributesBuffer);
gl.bufferData(gl.ARRAY_BUFFER, activeBuffer.subarray(0, bufferLength), gl.STREAM_DRAW);
// Bind the texture atlas if it's changed
if (this._atlas.hasCanvasChanged) {
this._atlas.hasCanvasChanged = false;
gl.uniform1i(this._textureLocation, 0);
gl.activeTexture(gl.TEXTURE0 + 0);
gl.bindTexture(gl.TEXTURE_2D, this._atlasTexture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, this._atlas.cacheCanvas);
gl.generateMipmap(gl.TEXTURE_2D);
}
// Set uniforms
gl.uniformMatrix4fv(this._projectionLocation, false, PROJECTION_MATRIX);
gl.uniform2f(this._resolutionLocation, gl.canvas.width, gl.canvas.height);
// Draw the viewport
gl.drawElementsInstanced(gl.TRIANGLES, 6, gl.UNSIGNED_BYTE, 0, bufferLength / INDICES_PER_CELL);
}
public setAtlas(atlas: ITextureAtlas): void {
const gl = this._gl;
this._atlas = atlas;
gl.bindTexture(gl.TEXTURE_2D, this._atlasTexture);
gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, atlas.cacheCanvas);
gl.generateMipmap(gl.TEXTURE_2D);
}
public setDimensions(dimensions: IRenderDimensions): void {
this._dimensions = dimensions;
}
}