rpgedit/src/view/tile.ts

import Renderer from './renderer/Renderer';

export type TileCoords = [number, number, number, number];

export class TileViewBuilder {
	private static pushTile(buf: number[], coords: TileCoords): void {
		const [x1, y1, x2, y2] = coords;

		buf.push(x1); buf.push(y1);
		buf.push(x2); buf.push(y1);
		buf.push(x1); buf.push(y2);

		buf.push(x1); buf.push(y2);
		buf.push(x2); buf.push(y1);
		buf.push(x2); buf.push(y2);
	}

	private readonly vertexData: number[] = [];
	private readonly textureData: number[] = [];

	constructor(private readonly r: Renderer, private readonly texture: WebGLTexture) {}

	public addTile(vertexCoords: TileCoords, texCoords: TileCoords): void {
		TileViewBuilder.pushTile(this.vertexData, vertexCoords);
		TileViewBuilder.pushTile(this.textureData, texCoords);
	}

	public build(): TileView {
		return new TileView(this.r, this.texture, this.vertexData, this.textureData);
	}
}

export class TileView {
	private readonly vertexCount: number;
	private readonly vertexBuffer: WebGLBuffer;
	private readonly textureBuffer: WebGLBuffer;

	constructor(
		private readonly r: Renderer,
		private readonly texture: WebGLTexture,
		vertexData: number[],
		textureData: number[],
	) {
		const gl = r.getContext();

		this.vertexBuffer = r.createBuffer();
		gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
		gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(vertexData), gl.STATIC_DRAW);

		this.textureBuffer = r.createBuffer();
		gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
		gl.bufferData(gl.ARRAY_BUFFER, new Float32Array(textureData), gl.STATIC_DRAW);

		this.vertexCount = vertexData.length / 2;
	}

	public render(): void {
		const gl = this.r.getContext();

		gl.clear(gl.COLOR_BUFFER_BIT);

		gl.activeTexture(gl.TEXTURE0);
		gl.bindTexture(gl.TEXTURE_2D, this.texture);
		gl.uniform1i(this.r.getSamplerLoc(), 0);

		gl.bindBuffer(gl.ARRAY_BUFFER, this.vertexBuffer);
		gl.vertexAttribPointer(this.r.getVertexPosLoc(), 2, gl.FLOAT, false, 0, 0);

		gl.bindBuffer(gl.ARRAY_BUFFER, this.textureBuffer);
		gl.vertexAttribPointer(this.r.getTextureCoordLoc(), 2, gl.FLOAT, false, 0, 0);

		gl.drawArrays(gl.TRIANGLES, 0, this.vertexCount);
	}
}