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Introduce ProgramConfiguration
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ProgramConfiguration contains code extracted from Bucket, Painter, and a few other key places, so that the logic implementing the shader #pragma system is located in a single place.

From the JSDoc:

ProgramConfiguration contains the logic for binding style layer properties and tile layer feature data into GL program uniforms and vertex attributes.

Non-data-driven property values are bound to shader uniforms. Data-driven property values are bound to vertex attributes. In order to support a uniform GLSL syntax over both, [Mapbox GL Shaders](https://github.com/mapbox/mapbox-gl-shaders) defines a `#pragma` abstraction, which ProgramConfiguration is responsible for implementing. At runtime, it examines the attributes of a particular layer, combines this with fixed knowledge about how layers of the particular type are implemented, and determines which uniforms and vertex attributes will be required. It can then substitute the appropriate text into the shader source code, create and link a program, and bind the uniforms and vertex attributes in preparation for drawing.
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@jfirebaugh
jfirebaugh committed Oct 21, 2016
1 parent b039848 commit 879150f
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Showing 10 changed files with 309 additions and 311 deletions.
197 changes: 25 additions & 172 deletions js/data/bucket.js
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Original file line number Diff line number Diff line change
Expand Up @@ -2,9 +2,8 @@

const ArrayGroup = require('./array_group');
const BufferGroup = require('./buffer_group');
const VertexArrayType = require('./vertex_array_type');
const ProgramConfiguration = require('./program_configuration');
const util = require('../util/util');
const assert = require('assert');

const FAKE_ZOOM_HISTORY = { lastIntegerZoom: Infinity, lastIntegerZoomTime: 0, lastZoom: 0 };

Expand Down Expand Up @@ -43,7 +42,13 @@ class Bucket {
this.minZoom = this.layer.minzoom;
this.maxZoom = this.layer.maxzoom;

this.paintAttributes = createPaintAttributes(this);
this.programConfigurations = util.mapObject(this.programInterfaces, (programInterface) => {
const result = {};
for (const layer of options.childLayers) {
result[layer.id] = ProgramConfiguration.createDynamic(programInterface.paintAttributes || [], layer, options);
}
return result;
});

if (options.arrays) {
const programInterfaces = this.programInterfaces;
Expand Down Expand Up @@ -119,13 +124,10 @@ class Bucket {

for (const programName in this.programInterfaces) {
this.arrayGroups[programName] = [];

const paintVertexArrayTypes = this.paintVertexArrayTypes[programName] = {};
const layerPaintAttributes = this.paintAttributes[programName];

for (const layerName in layerPaintAttributes) {
paintVertexArrayTypes[layerName] = new VertexArrayType(layerPaintAttributes[layerName].attributes);
}
this.paintVertexArrayTypes[programName] = util.mapObject(
this.programConfigurations[programName], (programConfiguration) => {
return programConfiguration.paintVertexArrayType();
});
}
}

Expand Down Expand Up @@ -168,15 +170,6 @@ class Bucket {
}
}

setUniforms(gl, programName, program, layer, globalProperties) {
const uniforms = this.paintAttributes[programName][layer.id].uniforms;
for (let i = 0; i < uniforms.length; i++) {
const uniform = uniforms[i];
const uniformLocation = program[uniform.name];
gl[`uniform${uniform.components}fv`](uniformLocation, uniform.getValue(layer, globalProperties));
}
}

serialize() {
return {
layerId: this.layer.id,
Expand Down Expand Up @@ -205,32 +198,25 @@ class Bucket {
}

populatePaintArrays(interfaceName, globalProperties, featureProperties, startGroup, startIndex) {
for (let l = 0; l < this.childLayers.length; l++) {
const layer = this.childLayers[l];
const groups = this.arrayGroups[interfaceName];
const groups = this.arrayGroups[interfaceName];
const programConfiguration = this.programConfigurations[interfaceName];

for (const layer of this.childLayers) {
for (let g = startGroup.index; g < groups.length; g++) {
const group = groups[g];
const start = g === startGroup.index ? startIndex : 0;
const length = group.layoutVertexArray.length;

const paintArray = group.paintVertexArrays[layer.id];
paintArray.resize(length);

const attributes = this.paintAttributes[interfaceName][layer.id].attributes;
for (let m = 0; m < attributes.length; m++) {
const attribute = attributes[m];

const value = attribute.getValue(layer, globalProperties, featureProperties);
const multiplier = attribute.multiplier || 1;
const components = attribute.components || 1;

const start = g === startGroup.index ? startIndex : 0;
for (let i = start; i < length; i++) {
const vertex = paintArray.get(i);
for (let c = 0; c < components; c++) {
const memberName = components > 1 ? (attribute.name + c) : attribute.name;
vertex[memberName] = value[c] * multiplier;
}
}
}
programConfiguration[layer.id].populatePaintArray(
layer,
paintArray,
start,
length,
globalProperties,
featureProperties);
}
}
}
Expand Down Expand Up @@ -260,136 +246,3 @@ Bucket.create = function(options) {
}
return new subclasses[type](options);
};

function createPaintAttributes(bucket) {
const attributes = {};
for (const interfaceName in bucket.programInterfaces) {
attributes[interfaceName] = {};

for (const childLayer of bucket.childLayers) {
attributes[interfaceName][childLayer.id] = {
attributes: [],
uniforms: [],
defines: [],
vertexPragmas: { define: {}, initialize: {} },
fragmentPragmas: { define: {}, initialize: {} }
};
}

const interfacePaintAttributes = bucket.programInterfaces[interfaceName].paintAttributes;
if (!interfacePaintAttributes) continue;

// "{precision} {type} tokens are replaced by arguments to the pragma
// https://github.com/mapbox/mapbox-gl-shaders#pragmas

for (const attribute of interfacePaintAttributes) {
attribute.multiplier = attribute.multiplier || 1;

for (const layer of bucket.childLayers) {
const paintAttributes = attributes[interfaceName][layer.id];
const fragmentInit = paintAttributes.fragmentPragmas.initialize;
const fragmentDefine = paintAttributes.fragmentPragmas.define;
const vertexInit = paintAttributes.vertexPragmas.initialize;
const vertexDefine = paintAttributes.vertexPragmas.define;

const inputName = attribute.name;
assert(attribute.name.slice(0, 2) === 'a_');
const name = attribute.name.slice(2);
const multiplier = attribute.multiplier.toFixed(1);

fragmentInit[name] = '';

if (layer.isPaintValueFeatureConstant(attribute.paintProperty)) {
paintAttributes.uniforms.push(attribute);

fragmentDefine[name] = vertexDefine[name] = `uniform {precision} {type} ${inputName};\n`;
fragmentInit[name] = vertexInit[name] = `{precision} {type} ${name} = ${inputName};\n`;

} else if (layer.isPaintValueZoomConstant(attribute.paintProperty)) {
paintAttributes.attributes.push(util.extend({}, attribute, {name: inputName}));

fragmentDefine[name] = `varying {precision} {type} ${name};\n`;
vertexDefine[name] = `varying {precision} {type} ${name};\n attribute {precision} {type} ${inputName};\n`;
vertexInit[name] = `${name} = ${inputName} / ${multiplier};\n`;

} else {
// Pick the index of the first offset to add to the buffers.
// Find the four closest stops, ideally with two on each side of the zoom level.
let numStops = 0;
const zoomLevels = layer.getPaintValueStopZoomLevels(attribute.paintProperty);
while (numStops < zoomLevels.length && zoomLevels[numStops] < bucket.zoom) numStops++;
const stopOffset = Math.max(0, Math.min(zoomLevels.length - 4, numStops - 2));

const fourZoomLevels = [];
for (let s = 0; s < 4; s++) {
fourZoomLevels.push(zoomLevels[Math.min(stopOffset + s, zoomLevels.length - 1)]);
}

const tName = `u_${name}_t`;

fragmentDefine[name] = `varying {precision} {type} ${name};\n`;
vertexDefine[name] = `varying {precision} {type} ${name};\n uniform lowp float ${tName};\n`;

paintAttributes.uniforms.push(util.extend({}, attribute, {
name: tName,
getValue: createGetUniform(attribute, stopOffset),
components: 1
}));

if (attribute.components === 1) {
paintAttributes.attributes.push(util.extend({}, attribute, {
getValue: createFunctionGetValue(attribute, fourZoomLevels),
isFunction: true,
components: attribute.components * 4
}));

vertexDefine[name] += `attribute {precision} vec4 ${inputName};\n`;
vertexInit[name] = `${name} = evaluate_zoom_function_1(${inputName}, ${tName}) / ${multiplier};\n`;

} else {
const inputNames = [];
for (let k = 0; k < 4; k++) {
inputNames.push(inputName + k);
paintAttributes.attributes.push(util.extend({}, attribute, {
getValue: createFunctionGetValue(attribute, [fourZoomLevels[k]]),
isFunction: true,
name: inputName + k
}));
vertexDefine[name] += `attribute {precision} {type} ${inputName + k};\n`;
}
vertexInit[name] = `${name} = evaluate_zoom_function_4(${inputNames.join(', ')}, ${tName}) / ${multiplier};\n`;
}
}
}
}
}
return attributes;
}

function createFunctionGetValue(attribute, stopZoomLevels) {
return function(layer, globalProperties, featureProperties) {
if (stopZoomLevels.length === 1) {
// return one multi-component value like color0
return attribute.getValue(layer, util.extend({}, globalProperties, { zoom: stopZoomLevels[0] }), featureProperties);
} else {
// pack multiple single-component values into a four component attribute
const values = [];
for (let z = 0; z < stopZoomLevels.length; z++) {
const stopZoomLevel = stopZoomLevels[z];
values.push(attribute.getValue(layer, util.extend({}, globalProperties, { zoom: stopZoomLevel }), featureProperties)[0]);
}
return values;
}
};
}

function createGetUniform(attribute, stopOffset) {
return function(layer, globalProperties) {
// stopInterp indicates which stops need to be interpolated.
// If stopInterp is 3.5 then interpolate half way between stops 3 and 4.
const stopInterp = layer.getPaintInterpolationT(attribute.paintProperty, globalProperties.zoom);
// We can only store four stop values in the buffers. stopOffset is the number of stops that come
// before the stops that were added to the buffers.
return [Math.max(0, Math.min(4, stopInterp - stopOffset))];
};
}
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