pica-gpu/dist/gl-helper.js

**GPU accelerated image resizer**

function compileShader(gl, type, source) {
    const shader = gl.createShader(type);
    gl.shaderSource(shader, source);
    gl.compileShader(shader);
    if (!gl.getShaderParameter(shader, gl.COMPILE_STATUS)) {
        console.error('compile shader error:', gl.getShaderInfoLog(shader));
        gl.deleteShader(shader);
        throw new Error('compile shader error');
    }
    return shader;
}
export function createProgram(gl, vsSource, fsSource) {
    const vertexShader = compileShader(gl, gl.VERTEX_SHADER, vsSource);
    const fragmentShader = compileShader(gl, gl.FRAGMENT_SHADER, fsSource);
    const program = gl.createProgram();
    gl.attachShader(program, vertexShader);
    gl.attachShader(program, fragmentShader);
    gl.linkProgram(program);
    if (!gl.getProgramParameter(program, gl.LINK_STATUS)) {
        console.error('link program error:', gl.getProgramInfoLog(program));
        throw new Error('link program error');
    }
    return {
        program,
        vertexShader,
        fragmentShader,
    };
}
export function createTextureFromImage(gl, image) {
    const texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.pixelStorei(gl.UNPACK_FLIP_Y_WEBGL, true);
    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);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, gl.RGBA, gl.UNSIGNED_BYTE, image);
    return texture;
}
export function createEmptyTexture(gl, width, height) {
    const texture = gl.createTexture();
    gl.bindTexture(gl.TEXTURE_2D, texture);
    gl.texImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, null);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR);
    gl.texParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR);
    return texture;
}
export function createFramebuffer(gl, texture) {
    const fb = gl.createFramebuffer();
    gl.bindFramebuffer(gl.FRAMEBUFFER, fb);
    gl.framebufferTexture2D(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, gl.TEXTURE_2D, texture, 0);
    return fb;
}
export function createDefaultQuadBuffer(gl) {
    const quadBuffer = gl.createBuffer();
    gl.bindBuffer(gl.ARRAY_BUFFER, quadBuffer);
    const quadVertices = new Float32Array([
        // x, y, u, v
        -1, -1, 0, 0, 1, -1, 1, 0, -1, 1, 0, 1, 1, 1, 1, 1,
    ]);
    gl.bufferData(gl.ARRAY_BUFFER, quadVertices, gl.STATIC_DRAW);
    return quadBuffer;
}
export function useDefaultQuadBuffer(gl, program, quadBuffer, position, textCoord) {
    const posLoc = gl.getAttribLocation(program, position);
    const texLoc = gl.getAttribLocation(program, textCoord);
    gl.bindBuffer(gl.ARRAY_BUFFER, quadBuffer);
    gl.enableVertexAttribArray(posLoc);
    gl.vertexAttribPointer(posLoc, 2, gl.FLOAT, false, 4 * 4, 0);
    gl.enableVertexAttribArray(texLoc);
    gl.vertexAttribPointer(texLoc, 2, gl.FLOAT, false, 4 * 4, 2 * 4);
}