Webgl / refactor utilities to work only on typed arrays

The base webgl renderer module now has two types of utilities:
* `writeXFeatureInstructions` will write a series of values in a given
typed array, which represent how a given feature will be rendered; for points,
this means position, size, color, etc.
* `writeXFeatureToBuffers` will fill up the given index & vertex buffers
with values based on the provided render instructions

As such, the logic for rendering features is:
user-input style > instructions array >(*) index/vertex buffers > draw

(*) this transformation is intended to be done on a worker.
This commit is contained in:
Olivier Guyot
2019-05-16 22:04:55 +02:00
parent 245ded43d4
commit eb912d95ca
2 changed files with 316 additions and 159 deletions

View File

@@ -61,90 +61,145 @@ class WebGLLayerRenderer extends LayerRenderer {
/**
* Pushes vertices and indices to the given buffers using the geometry coordinates and the following properties
* from the feature:
* - `color`
* - `opacity`
* - `size` (for points)
* - `u0`, `v0`, `u1`, `v1` (for points)
* - `rotateWithView` (for points)
* - `width` (for lines)
* Custom attributes can be designated using the `opt_attributes` argument, otherwise other properties on the
* feature will be ignored.
* @param {import("../../webgl/Buffer").default} vertexBuffer WebGL buffer in which new vertices will be pushed.
* @param {import("../../webgl/Buffer").default} indexBuffer WebGL buffer in which new indices will be pushed.
* @param {import("../../format/GeoJSON").GeoJSONFeature} geojsonFeature Feature in geojson format, coordinates
* expressed in EPSG:4326.
* @param {Array<string>} [opt_attributes] Custom attributes. An array of properties which will be read from the
* feature and pushed in the buffer in the given order. Note: attributes can only be numerical! Any other type or
* NaN will result in `0` being pushed in the buffer.
* @param {Float32Array} instructions Instructons array in which to write.
* @param {number} elementIndex Index from which render instructions will be written.
* @param {number} x Point center X coordinate
* @param {number} y Point center Y coordinate
* @param {number} u0 Left texture coordinate
* @param {number} v0 Bottom texture coordinate
* @param {number} u1 Right texture coordinate
* @param {number} v1 Top texture coordinate
* @param {number} size Radius of the point
* @param {number} opacity Opacity
* @param {boolean} rotateWithView If true, the point will stay aligned with the view
* @param {Array<number>} color Array holding red, green, blue, alpha values
* @return {number} Index from which the next element should be written
* @private
*/
export function pushFeatureToBuffer(vertexBuffer, indexBuffer, geojsonFeature, opt_attributes) {
if (!geojsonFeature.geometry) {
return;
}
switch (geojsonFeature.geometry.type) {
case 'Point':
pushPointFeatureToBuffer_(vertexBuffer, indexBuffer, geojsonFeature, opt_attributes);
return;
default:
return;
}
export function writePointFeatureInstructions(instructions, elementIndex, x, y, u0, v0, u1, v1, size, opacity, rotateWithView, color) {
let i = elementIndex;
instructions[i++] = x;
instructions[i++] = y;
instructions[i++] = u0;
instructions[i++] = v0;
instructions[i++] = u1;
instructions[i++] = v1;
instructions[i++] = size;
instructions[i++] = opacity;
instructions[i++] = rotateWithView ? 1 : 0;
instructions[i++] = color[0];
instructions[i++] = color[1];
instructions[i++] = color[2];
instructions[i++] = color[3];
return i;
}
const tmpArray_ = [];
const bufferPositions_ = {vertexPosition: 0, indexPosition: 0};
export const POINT_INSTRUCTIONS_COUNT = 13;
export const POINT_VERTEX_STRIDE = 12;
function writePointVertex(buffer, pos, x, y, offsetX, offsetY, u, v, opacity, rotateWithView, red, green, blue, alpha) {
buffer[pos + 0] = x;
buffer[pos + 1] = y;
buffer[pos + 2] = offsetX;
buffer[pos + 3] = offsetY;
buffer[pos + 4] = u;
buffer[pos + 5] = v;
buffer[pos + 6] = opacity;
buffer[pos + 7] = rotateWithView;
buffer[pos + 8] = red;
buffer[pos + 9] = green;
buffer[pos + 10] = blue;
buffer[pos + 11] = alpha;
}
function writeCustomAttrs(buffer, pos, customAttrs) {
if (customAttrs.length) {
buffer.set(customAttrs, pos);
}
}
/**
* An object holding positions both in an index and a vertex buffer.
* @typedef {Object} BufferPositions
* @property {number} vertexPosition Position in the vertex buffer
* @property {number} indexPosition Position in the index buffer
*/
/**
* Pushes a quad (two triangles) based on a point geometry
* @param {import("../../webgl/Buffer").default} vertexBuffer WebGL buffer
* @param {import("../../webgl/Buffer").default} indexBuffer WebGL buffer
* @param {import("../../format/GeoJSON").GeoJSONFeature} geojsonFeature Feature
* @param {Array<string>} [opt_attributes] Custom attributes
* @param {Float32Array} instructions Array of render instructions for points.
* @param {number} elementIndex Index from which render instructions will be read.
* @param {Float32Array} vertexBuffer Buffer in the form of a typed array.
* @param {Uint16Array|Uint32Array} indexBuffer Buffer in the form of a typed array.
* @param {BufferPositions} [bufferPositions] Buffer write positions; if not specified, positions will be set at 0.
* @param {number} [count] Amount of render instructions that will be read. Default value is POINT_INSTRUCTIONS_COUNT
* but a higher value can be provided; all values beyond the default count will be put in the vertices buffer as
* is, thus allowing specifying custom attributes. Please note: this value should not vary inside the same buffer or
* rendering will break.
* @return {BufferPositions} New buffer positions where to write next
* @property {number} vertexPosition New position in the vertex buffer where future writes should start.
* @property {number} indexPosition New position in the index buffer where future writes should start.
* @private
*/
function pushPointFeatureToBuffer_(vertexBuffer, indexBuffer, geojsonFeature, opt_attributes) {
const stride = 12 + (opt_attributes !== undefined ? opt_attributes.length : 0);
export function writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer, bufferPositions, count) {
const count_ = count > POINT_INSTRUCTIONS_COUNT ? count : POINT_INSTRUCTIONS_COUNT;
const x = geojsonFeature.geometry.coordinates[0];
const y = geojsonFeature.geometry.coordinates[1];
const u0 = geojsonFeature.properties.u0;
const v0 = geojsonFeature.properties.v0;
const u1 = geojsonFeature.properties.u1;
const v1 = geojsonFeature.properties.v1;
const size = geojsonFeature.properties.size;
const opacity = geojsonFeature.properties.opacity;
const rotateWithView = geojsonFeature.properties.rotateWithView;
const color = geojsonFeature.properties.color;
const red = color[0];
const green = color[1];
const blue = color[2];
const alpha = color[3];
const baseIndex = vertexBuffer.getArray().length / stride;
const x = instructions[elementIndex + 0];
const y = instructions[elementIndex + 1];
const u0 = instructions[elementIndex + 2];
const v0 = instructions[elementIndex + 3];
const u1 = instructions[elementIndex + 4];
const v1 = instructions[elementIndex + 5];
const size = instructions[elementIndex + 6];
const opacity = instructions[elementIndex + 7];
const rotateWithView = instructions[elementIndex + 8];
const red = instructions[elementIndex + 9];
const green = instructions[elementIndex + 10];
const blue = instructions[elementIndex + 11];
const alpha = instructions[elementIndex + 12];
// the default vertex buffer stride is 12, plus additional custom values if any
const baseStride = POINT_VERTEX_STRIDE;
const stride = baseStride + count_ - POINT_INSTRUCTIONS_COUNT;
// read custom numerical attributes on the feature
const customAttributeValues = tmpArray_;
customAttributeValues.length = opt_attributes ? opt_attributes.length : 0;
for (let i = 0; i < customAttributeValues.length; i++) {
customAttributeValues[i] = parseFloat(geojsonFeature.properties[opt_attributes[i]]) || 0;
const customAttrs = tmpArray_;
customAttrs.length = count_ - POINT_INSTRUCTIONS_COUNT;
for (let i = 0; i < customAttrs.length; i++) {
customAttrs[i] = instructions[elementIndex + POINT_INSTRUCTIONS_COUNT + i];
}
let vPos = bufferPositions ? bufferPositions.vertexPosition : 0;
let iPos = bufferPositions ? bufferPositions.indexPosition : 0;
const baseIndex = vPos / stride;
// push vertices for each of the four quad corners (first standard then custom attributes)
vertexBuffer.getArray().push(x, y, -size / 2, -size / 2, u0, v0, opacity, rotateWithView, red, green, blue, alpha);
Array.prototype.push.apply(vertexBuffer.getArray(), customAttributeValues);
writePointVertex(vertexBuffer, vPos, x, y, -size / 2, -size / 2, u0, v0, opacity, rotateWithView, red, green, blue, alpha);
writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
vPos += stride;
vertexBuffer.getArray().push(x, y, +size / 2, -size / 2, u1, v0, opacity, rotateWithView, red, green, blue, alpha);
Array.prototype.push.apply(vertexBuffer.getArray(), customAttributeValues);
writePointVertex(vertexBuffer, vPos, x, y, +size / 2, -size / 2, u1, v0, opacity, rotateWithView, red, green, blue, alpha);
writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
vPos += stride;
vertexBuffer.getArray().push(x, y, +size / 2, +size / 2, u1, v1, opacity, rotateWithView, red, green, blue, alpha);
Array.prototype.push.apply(vertexBuffer.getArray(), customAttributeValues);
writePointVertex(vertexBuffer, vPos, x, y, +size / 2, +size / 2, u1, v1, opacity, rotateWithView, red, green, blue, alpha);
writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
vPos += stride;
vertexBuffer.getArray().push(x, y, -size / 2, +size / 2, u0, v1, opacity, rotateWithView, red, green, blue, alpha);
Array.prototype.push.apply(vertexBuffer.getArray(), customAttributeValues);
writePointVertex(vertexBuffer, vPos, x, y, -size / 2, +size / 2, u0, v1, opacity, rotateWithView, red, green, blue, alpha);
writeCustomAttrs(vertexBuffer, vPos + baseStride, customAttrs);
vPos += stride;
indexBuffer.getArray().push(
baseIndex, baseIndex + 1, baseIndex + 3,
baseIndex + 1, baseIndex + 2, baseIndex + 3
);
indexBuffer[iPos++] = baseIndex; indexBuffer[iPos++] = baseIndex + 1; indexBuffer[iPos++] = baseIndex + 3;
indexBuffer[iPos++] = baseIndex + 1; indexBuffer[iPos++] = baseIndex + 2; indexBuffer[iPos++] = baseIndex + 3;
bufferPositions_.vertexPosition = vPos;
bufferPositions_.indexPosition = iPos;
return bufferPositions_;
}
/**

View File

@@ -1,5 +1,7 @@
import WebGLLayerRenderer, {getBlankTexture, pushFeatureToBuffer} from '../../../../../src/ol/renderer/webgl/Layer.js';
import WebGLArrayBuffer from '../../../../../src/ol/webgl/Buffer.js';
import WebGLLayerRenderer, {
getBlankTexture, POINT_INSTRUCTIONS_COUNT, POINT_VERTEX_STRIDE,
writePointFeatureInstructions, writePointFeatureToBuffers
} from '../../../../../src/ol/renderer/webgl/Layer.js';
import Layer from '../../../../../src/ol/layer/Layer.js';
@@ -28,111 +30,211 @@ describe('ol.renderer.webgl.Layer', function() {
});
describe('pushFeatureToBuffer', function() {
let vertexBuffer, indexBuffer;
describe('writePointFeatureInstructions', function() {
let instructions;
beforeEach(function() {
vertexBuffer = new WebGLArrayBuffer();
indexBuffer = new WebGLArrayBuffer();
instructions = new Float32Array(100);
});
it('does nothing if the feature has no geometry', function() {
const feature = {
type: 'Feature',
id: 'AFG',
properties: {
color: [0.5, 1, 0.2, 0.7],
size: 3
},
geometry: null
};
pushFeatureToBuffer(vertexBuffer, indexBuffer, feature);
expect(vertexBuffer.getArray().length).to.eql(0);
expect(indexBuffer.getArray().length).to.eql(0);
it('writes instructions corresponding to the given parameters', function() {
const baseIndex = 17;
writePointFeatureInstructions(instructions, baseIndex,
1, 2, 3, 4, 5, 6,
7, 8, true, [10, 11, 12, 13]);
expect(instructions[baseIndex + 0]).to.eql(1);
expect(instructions[baseIndex + 1]).to.eql(2);
expect(instructions[baseIndex + 2]).to.eql(3);
expect(instructions[baseIndex + 3]).to.eql(4);
expect(instructions[baseIndex + 4]).to.eql(5);
expect(instructions[baseIndex + 5]).to.eql(6);
expect(instructions[baseIndex + 6]).to.eql(7);
expect(instructions[baseIndex + 7]).to.eql(8);
expect(instructions[baseIndex + 8]).to.eql(1);
expect(instructions[baseIndex + 9]).to.eql(10);
expect(instructions[baseIndex + 10]).to.eql(11);
expect(instructions[baseIndex + 11]).to.eql(12);
expect(instructions[baseIndex + 12]).to.eql(13);
});
it('adds two triangles with the correct attributes for a point geometry', function() {
const feature = {
type: 'Feature',
id: 'AFG',
properties: {
color: [0.5, 1, 0.2, 0.7],
size: 3
},
geometry: {
type: 'Point',
coordinates: [-75, 47]
}
};
const attributePerVertex = 12;
pushFeatureToBuffer(vertexBuffer, indexBuffer, feature);
expect(vertexBuffer.getArray().length).to.eql(attributePerVertex * 4);
expect(indexBuffer.getArray().length).to.eql(6);
it('correctly chains writes', function() {
let baseIndex = 0;
baseIndex = writePointFeatureInstructions(instructions, baseIndex,
1, 2, 3, 4, 5, 6,
7, 8, true, [10, 11, 12, 13]);
baseIndex = writePointFeatureInstructions(instructions, baseIndex,
1, 2, 3, 4, 5, 6,
7, 8, true, [10, 11, 12, 13]);
writePointFeatureInstructions(instructions, baseIndex,
1, 2, 3, 4, 5, 6,
7, 8, true, [10, 11, 12, 13]);
expect(instructions[baseIndex + 0]).to.eql(1);
expect(instructions[baseIndex + 1]).to.eql(2);
expect(instructions[baseIndex + 2]).to.eql(3);
expect(instructions[baseIndex + 3]).to.eql(4);
expect(instructions[baseIndex + 4]).to.eql(5);
expect(instructions[baseIndex + 5]).to.eql(6);
expect(instructions[baseIndex + 6]).to.eql(7);
expect(instructions[baseIndex + 7]).to.eql(8);
expect(instructions[baseIndex + 8]).to.eql(1);
expect(instructions[baseIndex + 9]).to.eql(10);
expect(instructions[baseIndex + 10]).to.eql(11);
expect(instructions[baseIndex + 11]).to.eql(12);
expect(instructions[baseIndex + 12]).to.eql(13);
});
});
describe('writePointFeatureToBuffers', function() {
let vertexBuffer, indexBuffer, instructions, elementIndex;
beforeEach(function() {
vertexBuffer = new Float32Array(100);
indexBuffer = new Uint16Array(100);
instructions = new Float32Array(100);
elementIndex = 3;
writePointFeatureInstructions(instructions, elementIndex,
1, 2, 3, 4, 5, 6,
7, 8, true, [10, 11, 12, 13]);
});
it('correctly sets indices & coordinates for several features', function() {
const feature = {
type: 'Feature',
id: 'AFG',
properties: {
color: [0.5, 1, 0.2, 0.7],
size: 3
},
geometry: {
type: 'Point',
coordinates: [-75, 47]
}
};
const attributePerVertex = 12;
pushFeatureToBuffer(vertexBuffer, indexBuffer, feature);
pushFeatureToBuffer(vertexBuffer, indexBuffer, feature);
expect(vertexBuffer.getArray()[0]).to.eql(-75);
expect(vertexBuffer.getArray()[1]).to.eql(47);
expect(vertexBuffer.getArray()[0 + attributePerVertex]).to.eql(-75);
expect(vertexBuffer.getArray()[1 + attributePerVertex]).to.eql(47);
it('writes correctly to the buffers (without custom attributes)', function() {
const stride = POINT_VERTEX_STRIDE;
const positions = writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer);
// first point
expect(indexBuffer.getArray()[0]).to.eql(0);
expect(indexBuffer.getArray()[1]).to.eql(1);
expect(indexBuffer.getArray()[2]).to.eql(3);
expect(indexBuffer.getArray()[3]).to.eql(1);
expect(indexBuffer.getArray()[4]).to.eql(2);
expect(indexBuffer.getArray()[5]).to.eql(3);
expect(vertexBuffer[0]).to.eql(1);
expect(vertexBuffer[1]).to.eql(2);
expect(vertexBuffer[2]).to.eql(-3.5);
expect(vertexBuffer[3]).to.eql(-3.5);
expect(vertexBuffer[4]).to.eql(3);
expect(vertexBuffer[5]).to.eql(4);
expect(vertexBuffer[6]).to.eql(8);
expect(vertexBuffer[7]).to.eql(1);
expect(vertexBuffer[8]).to.eql(10);
expect(vertexBuffer[9]).to.eql(11);
expect(vertexBuffer[10]).to.eql(12);
expect(vertexBuffer[11]).to.eql(13);
// second point
expect(indexBuffer.getArray()[6]).to.eql(4);
expect(indexBuffer.getArray()[7]).to.eql(5);
expect(indexBuffer.getArray()[8]).to.eql(7);
expect(indexBuffer.getArray()[9]).to.eql(5);
expect(indexBuffer.getArray()[10]).to.eql(6);
expect(indexBuffer.getArray()[11]).to.eql(7);
expect(vertexBuffer[stride + 0]).to.eql(1);
expect(vertexBuffer[stride + 1]).to.eql(2);
expect(vertexBuffer[stride + 2]).to.eql(+3.5);
expect(vertexBuffer[stride + 3]).to.eql(-3.5);
expect(vertexBuffer[stride + 4]).to.eql(5);
expect(vertexBuffer[stride + 5]).to.eql(4);
expect(vertexBuffer[stride * 2 + 0]).to.eql(1);
expect(vertexBuffer[stride * 2 + 1]).to.eql(2);
expect(vertexBuffer[stride * 2 + 2]).to.eql(+3.5);
expect(vertexBuffer[stride * 2 + 3]).to.eql(+3.5);
expect(vertexBuffer[stride * 2 + 4]).to.eql(5);
expect(vertexBuffer[stride * 2 + 5]).to.eql(6);
expect(vertexBuffer[stride * 3 + 0]).to.eql(1);
expect(vertexBuffer[stride * 3 + 1]).to.eql(2);
expect(vertexBuffer[stride * 3 + 2]).to.eql(-3.5);
expect(vertexBuffer[stride * 3 + 3]).to.eql(+3.5);
expect(vertexBuffer[stride * 3 + 4]).to.eql(3);
expect(vertexBuffer[stride * 3 + 5]).to.eql(6);
expect(indexBuffer[0]).to.eql(0);
expect(indexBuffer[1]).to.eql(1);
expect(indexBuffer[2]).to.eql(3);
expect(indexBuffer[3]).to.eql(1);
expect(indexBuffer[4]).to.eql(2);
expect(indexBuffer[5]).to.eql(3);
expect(positions.indexPosition).to.eql(6);
expect(positions.vertexPosition).to.eql(stride * 4);
});
it('correctly adds custom attributes', function() {
const feature = {
type: 'Feature',
id: 'AFG',
properties: {
color: [0.5, 1, 0.2, 0.7],
custom: 4,
customString: '5',
custom2: 12.4,
customString2: 'abc'
},
geometry: {
type: 'Point',
coordinates: [-75, 47]
}
};
const attributePerVertex = 16;
pushFeatureToBuffer(vertexBuffer, indexBuffer, feature, ['custom', 'custom2', 'customString', 'customString2']);
expect(vertexBuffer.getArray().length).to.eql(attributePerVertex * 4);
expect(indexBuffer.getArray().length).to.eql(6);
expect(vertexBuffer.getArray()[12]).to.eql(4);
expect(vertexBuffer.getArray()[13]).to.eql(12.4);
expect(vertexBuffer.getArray()[14]).to.eql(5);
expect(vertexBuffer.getArray()[15]).to.eql(0);
it('writes correctly to the buffers (with custom attributes)', function() {
instructions[elementIndex + POINT_INSTRUCTIONS_COUNT] = 101;
instructions[elementIndex + POINT_INSTRUCTIONS_COUNT + 1] = 102;
instructions[elementIndex + POINT_INSTRUCTIONS_COUNT + 2] = 103;
const stride = POINT_VERTEX_STRIDE + 3;
const positions = writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer,
undefined, POINT_INSTRUCTIONS_COUNT + 3);
expect(vertexBuffer[0]).to.eql(1);
expect(vertexBuffer[1]).to.eql(2);
expect(vertexBuffer[2]).to.eql(-3.5);
expect(vertexBuffer[3]).to.eql(-3.5);
expect(vertexBuffer[4]).to.eql(3);
expect(vertexBuffer[5]).to.eql(4);
expect(vertexBuffer[6]).to.eql(8);
expect(vertexBuffer[7]).to.eql(1);
expect(vertexBuffer[8]).to.eql(10);
expect(vertexBuffer[9]).to.eql(11);
expect(vertexBuffer[10]).to.eql(12);
expect(vertexBuffer[11]).to.eql(13);
expect(vertexBuffer[12]).to.eql(101);
expect(vertexBuffer[13]).to.eql(102);
expect(vertexBuffer[14]).to.eql(103);
expect(vertexBuffer[stride + 12]).to.eql(101);
expect(vertexBuffer[stride + 13]).to.eql(102);
expect(vertexBuffer[stride + 14]).to.eql(103);
expect(vertexBuffer[stride * 2 + 12]).to.eql(101);
expect(vertexBuffer[stride * 2 + 13]).to.eql(102);
expect(vertexBuffer[stride * 2 + 14]).to.eql(103);
expect(vertexBuffer[stride * 3 + 12]).to.eql(101);
expect(vertexBuffer[stride * 3 + 13]).to.eql(102);
expect(vertexBuffer[stride * 3 + 14]).to.eql(103);
expect(indexBuffer[0]).to.eql(0);
expect(indexBuffer[1]).to.eql(1);
expect(indexBuffer[2]).to.eql(3);
expect(indexBuffer[3]).to.eql(1);
expect(indexBuffer[4]).to.eql(2);
expect(indexBuffer[5]).to.eql(3);
expect(positions.indexPosition).to.eql(6);
expect(positions.vertexPosition).to.eql(stride * 4);
});
it('correctly chains buffer writes', function() {
const stride = POINT_VERTEX_STRIDE;
let positions = writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer);
positions = writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer, positions);
positions = writePointFeatureToBuffers(instructions, elementIndex, vertexBuffer, indexBuffer, positions);
expect(vertexBuffer[0]).to.eql(1);
expect(vertexBuffer[1]).to.eql(2);
expect(vertexBuffer[2]).to.eql(-3.5);
expect(vertexBuffer[3]).to.eql(-3.5);
expect(vertexBuffer[stride * 4 + 0]).to.eql(1);
expect(vertexBuffer[stride * 4 + 1]).to.eql(2);
expect(vertexBuffer[stride * 4 + 2]).to.eql(-3.5);
expect(vertexBuffer[stride * 4 + 3]).to.eql(-3.5);
expect(vertexBuffer[stride * 8 + 0]).to.eql(1);
expect(vertexBuffer[stride * 8 + 1]).to.eql(2);
expect(vertexBuffer[stride * 8 + 2]).to.eql(-3.5);
expect(vertexBuffer[stride * 8 + 3]).to.eql(-3.5);
expect(indexBuffer[6 + 0]).to.eql(4);
expect(indexBuffer[6 + 1]).to.eql(5);
expect(indexBuffer[6 + 2]).to.eql(7);
expect(indexBuffer[6 + 3]).to.eql(5);
expect(indexBuffer[6 + 4]).to.eql(6);
expect(indexBuffer[6 + 5]).to.eql(7);
expect(indexBuffer[6 * 2 + 0]).to.eql(8);
expect(indexBuffer[6 * 2 + 1]).to.eql(9);
expect(indexBuffer[6 * 2 + 2]).to.eql(11);
expect(indexBuffer[6 * 2 + 3]).to.eql(9);
expect(indexBuffer[6 * 2 + 4]).to.eql(10);
expect(indexBuffer[6 * 2 + 5]).to.eql(11);
expect(positions.indexPosition).to.eql(6 * 3);
expect(positions.vertexPosition).to.eql(stride * 4 * 3);
});
});
describe('getBlankTexture', function() {