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60 lines
1.7 KiB
60 lines
1.7 KiB
8 years ago
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module.exports = class GLFontCache {
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constructor (gl) {
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this.gl = gl
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// cache: string => WebGLTexture
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this.cache = new Map()
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this.dp = 1
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this.cellSize = { width: 0, height: 0 }
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this.canvas = document.createElement('canvas')
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this.ctx = this.canvas.getContext('2d')
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}
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clearCache () {
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for (let texture of this.cache.values()) this.gl.deleteTexture(texture)
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this.cache = new Map()
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}
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getChar (font, character) {
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let name = `${font}@${this.dp}x:${character}`
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if (!this.cache.has(name)) {
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this.cache.set(name, this.render(font, character))
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}
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return this.cache.get(name)
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}
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render (font, character) {
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const { gl, ctx, dp, cellSize } = this
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let width = dp * cellSize.width * 3
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let height = dp * cellSize.height * 3
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if (this.canvas.width !== width) this.canvas.width = width
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if (this.canvas.height !== height) this.canvas.height = height
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ctx.setTransform(1, 0, 0, 1, 0, 0)
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ctx.clearRect(0, 0, width, height)
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ctx.scale(dp, dp)
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if (ctx.font !== font) ctx.font = font
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ctx.textAlign = 'center'
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ctx.textBaseline = 'middle'
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ctx.fillStyle = 'white'
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ctx.fillText(character, cellSize.width * 1.5, cellSize.height * 1.5)
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let imageData = ctx.getImageData(0, 0, width, height)
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let texture = gl.createTexture()
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gl.bindTexture(gl.TEXTURE_2D, texture)
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gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, imageData)
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
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gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
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return texture
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}
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}
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