maplibre-gl/src/render/program/raster_program.ts

BSD licensed community fork of mapbox-gl, a WebGL interactive maps library

import {Uniform1i, Uniform1f, Uniform2f, Uniform3f, Uniform4f} from '../uniform_binding';

import type {Context} from '../../gl/context';
import type {UniformValues, UniformLocations} from '../uniform_binding';
import type {RasterStyleLayer} from '../../style/style_layer/raster_style_layer';
import type Point from '@mapbox/point-geometry';

export type RasterUniformsType = {
    'u_tl_parent': Uniform2f;
    'u_scale_parent': Uniform1f;
    'u_buffer_scale': Uniform1f;
    'u_fade_t': Uniform1f;
    'u_opacity': Uniform1f;
    'u_image0': Uniform1i;
    'u_image1': Uniform1i;
    'u_brightness_low': Uniform1f;
    'u_brightness_high': Uniform1f;
    'u_saturation_factor': Uniform1f;
    'u_contrast_factor': Uniform1f;
    'u_spin_weights': Uniform3f;
    'u_coords_top': Uniform4f;
    'u_coords_bottom': Uniform4f;
};

const rasterUniforms = (context: Context, locations: UniformLocations): RasterUniformsType => ({
    'u_tl_parent': new Uniform2f(context, locations.u_tl_parent),
    'u_scale_parent': new Uniform1f(context, locations.u_scale_parent),
    'u_buffer_scale': new Uniform1f(context, locations.u_buffer_scale),
    'u_fade_t': new Uniform1f(context, locations.u_fade_t),
    'u_opacity': new Uniform1f(context, locations.u_opacity),
    'u_image0': new Uniform1i(context, locations.u_image0),
    'u_image1': new Uniform1i(context, locations.u_image1),
    'u_brightness_low': new Uniform1f(context, locations.u_brightness_low),
    'u_brightness_high': new Uniform1f(context, locations.u_brightness_high),
    'u_saturation_factor': new Uniform1f(context, locations.u_saturation_factor),
    'u_contrast_factor': new Uniform1f(context, locations.u_contrast_factor),
    'u_spin_weights': new Uniform3f(context, locations.u_spin_weights),
    'u_coords_top': new Uniform4f(context, locations.u_coords_top),
    'u_coords_bottom': new Uniform4f(context, locations.u_coords_bottom)
});

const rasterUniformValues = (
    parentTL: [number, number],
    parentScaleBy: number,
    fade: {
        mix: number;
        opacity: number;
    },
    layer: RasterStyleLayer,
    cornerCoords: Array<Point>,
): UniformValues<RasterUniformsType> => ({
    'u_tl_parent': parentTL,
    'u_scale_parent': parentScaleBy,
    // If u_buffer_scale is ever something else than a constant 1,
    // the north/south pole handling in the vertex shader might need modification
    // so that the texture coordinares for poles always lie beyond the edge of the texture.
    // Right now the coordinates are placed right at the texture border.
    'u_buffer_scale': 1,
    'u_fade_t': fade.mix,
    'u_opacity': fade.opacity * layer.paint.get('raster-opacity'),
    'u_image0': 0,
    'u_image1': 1,
    'u_brightness_low': layer.paint.get('raster-brightness-min'),
    'u_brightness_high': layer.paint.get('raster-brightness-max'),
    'u_saturation_factor': saturationFactor(layer.paint.get('raster-saturation')),
    'u_contrast_factor': contrastFactor(layer.paint.get('raster-contrast')),
    'u_spin_weights': spinWeights(layer.paint.get('raster-hue-rotate')),
    'u_coords_top': [cornerCoords[0].x, cornerCoords[0].y, cornerCoords[1].x, cornerCoords[1].y],
    'u_coords_bottom': [cornerCoords[3].x, cornerCoords[3].y, cornerCoords[2].x, cornerCoords[2].y]
});

function spinWeights(angle) {
    angle *= Math.PI / 180;
    const s = Math.sin(angle);
    const c = Math.cos(angle);
    return [
        (2 * c + 1) / 3,
        (-Math.sqrt(3) * s - c + 1) / 3,
        (Math.sqrt(3) * s - c + 1) / 3
    ];
}

function contrastFactor(contrast) {
    return contrast > 0 ?
        1 / (1 - contrast) :
        1 + contrast;
}

function saturationFactor(saturation) {
    return saturation > 0 ?
        1 - 1 / (1.001 - saturation) :
        -saturation;
}

export {rasterUniforms, rasterUniformValues};