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Separate 2D buffer generation into its own stage
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Janine Liu committed May 20, 2022
1 parent 3277015 commit 2b923a0
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Showing 7 changed files with 653 additions and 377 deletions.
251 changes: 5 additions & 246 deletions Source/Scene/ModelExperimental/GeometryPipelineStage.js
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Original file line number Diff line number Diff line change
@@ -1,23 +1,15 @@
import AttributeType from "../AttributeType.js";
import BoundingSphere from "../../Core/BoundingSphere.js";
import Buffer from "../../Renderer/Buffer.js";
import BufferUsage from "../../Renderer/BufferUsage.js";
import Cartesian3 from "../../Core/Cartesian3.js";
import clone from "../../Core/clone.js";
import combine from "../../Core/combine.js";
import ComponentDatatype from "../../Core/ComponentDatatype.js";
import defined from "../../Core/defined.js";
import GeometryStageFS from "../../Shaders/ModelExperimental/GeometryStageFS.js";
import GeometryStageVS from "../../Shaders/ModelExperimental/GeometryStageVS.js";
import Matrix4 from "../../Core/Matrix4.js";
import ModelExperimentalUtility from "./ModelExperimentalUtility.js";
import ModelExperimentalType from "./ModelExperimentalType.js";
import PrimitiveType from "../../Core/PrimitiveType.js";
import SceneMode from "../SceneMode.js";
import SelectedFeatureIdPipelineStage from "./SelectedFeatureIdPipelineStage.js";
import ShaderDestination from "../../Renderer/ShaderDestination.js";
import VertexAttributeSemantic from "../VertexAttributeSemantic.js";
import SceneTransforms from "../SceneTransforms.js";

/**
* The geometry pipeline stage processes the vertex attributes of a primitive.
Expand Down Expand Up @@ -58,9 +50,7 @@ GeometryPipelineStage.FUNCTION_SIGNATURE_SET_DYNAMIC_VARYINGS =
*
* If the scene is not 3D only, this stage also:
* <ul>
* <li> creates a vertex buffer for the projected positions of the primitive in 2D
* <li> adds an attribute for the 2D positions
* <li> adds a uniform for the view model matrix in 2D
* </ul>
*
* @param {PrimitiveRenderResources} renderResources The render resources for this primitive.
Expand Down Expand Up @@ -146,10 +136,6 @@ GeometryPipelineStage.process = function (
const mode = frameState.mode;
const use2D = mode === SceneMode.SCENE2D || mode === SceneMode.COLUMBUS_VIEW;

// The reference point, a.k.a. the center of the projected bounding sphere,
// will be computed and stored when the position attribute is processed. This is
// used for the 2D model matrix uniform.
let referencePoint2D;
for (let i = 0; i < primitive.attributes.length; i++) {
const attribute = primitive.attributes[i];
const attributeLocationCount = AttributeType.getAttributeLocationCount(
Expand Down Expand Up @@ -178,10 +164,6 @@ GeometryPipelineStage.process = function (
frameState,
use2D
);

if (isPositionAttribute) {
referencePoint2D = attribute.referencePoint2D;
}
}

handleBitangents(shaderBuilder, primitive.attributes);
Expand All @@ -192,38 +174,6 @@ GeometryPipelineStage.process = function (

shaderBuilder.addVertexLines([GeometryStageVS]);
shaderBuilder.addFragmentLines([GeometryStageFS]);

// Handle the shader define and model matrix uniform for 2D
if (use2D) {
shaderBuilder.addDefine(
"USE_2D_POSITIONS",
undefined,
ShaderDestination.VERTEX
);
shaderBuilder.addUniform("mat4", "u_modelView2D", ShaderDestination.VERTEX);

const modelMatrix = Matrix4.fromTranslation(
referencePoint2D,
new Matrix4()
);
const modelView = new Matrix4();

const camera = frameState.camera;
const uniformMap = {
u_modelView2D: function () {
return Matrix4.multiplyTransformation(
camera.viewMatrix,
modelMatrix,
modelView
);
},
};

renderResources.uniformMap = combine(
uniformMap,
renderResources.uniformMap
);
}
};

function processAttribute(
Expand All @@ -250,7 +200,6 @@ function processAttribute(
renderResources,
attribute,
attributeIndex,
frameState,
use2D
);
}
Expand Down Expand Up @@ -295,7 +244,6 @@ function addAttributeToRenderResources(
renderResources,
attribute,
attributeIndex,
frameState,
use2D
) {
const quantization = attribute.quantization;
Expand Down Expand Up @@ -337,29 +285,19 @@ function addAttributeToRenderResources(

renderResources.attributes.push(vertexAttribute);

if (!isPositionAttribute) {
return;
}

// If the position typed array exists, project the positions and
// store them in a separate GPU buffer in the attribute.
if (defined(attribute.typedArray)) {
modifyAttributeFor2D(attribute, renderResources, frameState);
attribute.typedArray = undefined;
}

if (!use2D) {
if (!isPositionAttribute || !use2D) {
return;
}

// Add an additional attribute for the projected positions in 2D / CV.
const buffer2D = renderResources.runtimePrimitive.positionBuffer2D;
const positionAttribute2D = {
index: attributeIndex,
value: defined(attribute.buffer2D) ? undefined : attribute.constant,
vertexBuffer: attribute.buffer2D,
value: buffer2D ? undefined : attribute.constant,
vertexBuffer: buffer2D,
count: attribute.count,
componentsPerAttribute: componentsPerAttribute,
componentDatatype: ComponentDatatype.FLOAT, // The positions will always be projected as floats.
componentDatatype: ComponentDatatype.FLOAT, // The projected positions will always be floats.
offsetInBytes: attribute.byteOffset,
strideInBytes: attribute.byteStride,
normalize: attribute.normalized,
Expand Down Expand Up @@ -592,183 +530,4 @@ function handleBitangents(shaderBuilder, attributes) {
);
}

const scratchPosition = new Cartesian3();

function dequantizePositionsTypedArray(typedArray, quantization) {
// Draco compression is normally handled in the shader, but it must
// be decoded here to project the positions to 2D / CV.
const length = typedArray.length;
const dequantizedArray = new Float32Array(length);
const quantizedVolumeOffset = quantization.quantizedVolumeOffset;
const quantizedVolumeStepSize = quantization.quantizedVolumeStepSize;
for (let i = 0; i < length; i += 3) {
const initialPosition = Cartesian3.fromArray(
typedArray,
i,
scratchPosition
);
const scaledPosition = Cartesian3.multiplyComponents(
initialPosition,
quantizedVolumeStepSize,
initialPosition
);
const dequantizedPosition = Cartesian3.add(
scaledPosition,
quantizedVolumeOffset,
scaledPosition
);

dequantizedArray[i] = dequantizedPosition.x;
dequantizedArray[i + 1] = dequantizedPosition.y;
dequantizedArray[i + 2] = dequantizedPosition.z;
}

return dequantizedArray;
}

function createPositionsTypedArrayFor2D(
attribute,
modelMatrix,
frameState,
referencePoint
) {
const typedArray = attribute.typedArray;

let result;
if (defined(attribute.quantization)) {
// Dequantize the positions if necessary.
result = dequantizePositionsTypedArray(
attribute.typedArray,
attribute.quantization
);
} else {
result = new Float32Array(
typedArray.buffer,
typedArray.byteOffset,
typedArray.byteLength / Float32Array.BYTES_PER_ELEMENT
);
}

const startIndex = attribute.byteOffset / Float32Array.BYTES_PER_ELEMENT;
const length = result.length;
for (let i = startIndex; i < length; i += 3) {
const initialPosition = Cartesian3.fromArray(result, i, scratchPosition);

const transformedPosition = Matrix4.multiplyByPoint(
modelMatrix,
initialPosition,
initialPosition
);

const projectedPosition = SceneTransforms.computeActualWgs84Position(
frameState,
transformedPosition,
transformedPosition
);

// To prevent jitter, the positions are defined relative to
// a common reference point. For convenience, this is the center
// of the primitive's bounding sphere.
const relativePosition = Cartesian3.subtract(
projectedPosition,
referencePoint,
projectedPosition
);

result[i] = relativePosition.x;
result[i + 1] = relativePosition.y;
result[i + 2] = relativePosition.z;
}

return result;
}

const scratchMatrix = new Matrix4();
const scratchProjectedMin = new Cartesian3();
const scratchProjectedMax = new Cartesian3();
const scratchBoundingSphere = new BoundingSphere();

function computeReferencePoint(
positionMin,
positionMax,
modelMatrix,
frameState
) {
// Compute the bounding sphere in 2D.
const transformedPositionMin = Matrix4.multiplyByPoint(
modelMatrix,
positionMin,
scratchProjectedMin
);

const projectedMin = SceneTransforms.computeActualWgs84Position(
frameState,
transformedPositionMin,
transformedPositionMin
);

const transformedPositionMax = Matrix4.multiplyByPoint(
modelMatrix,
positionMax,
scratchProjectedMax
);

const projectedMax = SceneTransforms.computeActualWgs84Position(
frameState,
transformedPositionMax,
transformedPositionMax
);

const boundingSphere = BoundingSphere.fromCornerPoints(
projectedMin,
projectedMax,
scratchBoundingSphere
);

// Use the center of the 2D bounding sphere as the reference point.
return Cartesian3.clone(boundingSphere.center, new Cartesian3());
}

function modifyAttributeFor2D(attribute, renderResources, frameState) {
const sceneGraph = renderResources.model.sceneGraph;
const modelMatrix = sceneGraph.computedModelMatrix;
const nodeComputedTransform = renderResources.runtimeNode.computedTransform;
const computedModelMatrix = Matrix4.multiplyTransformation(
modelMatrix,
nodeComputedTransform,
scratchMatrix
);

// Force the scene mode to be CV. In 2D, the projected position will have an
// x-coordinate of 0, which will be problematic when switching to CV mode.
const frameStateCV = clone(frameState);
frameStateCV.mode = SceneMode.COLUMBUS_VIEW;

// Project positions relative to the 2D bounding sphere's center.
const referencePoint = computeReferencePoint(
renderResources.positionMin,
renderResources.positionMax,
computedModelMatrix,
frameStateCV
);
const projectedPositions = createPositionsTypedArrayFor2D(
attribute,
computedModelMatrix,
frameStateCV,
referencePoint
);

// Put the resulting data in a GPU buffer.
const buffer = Buffer.createVertexBuffer({
context: frameState.context,
typedArray: projectedPositions,
usage: BufferUsage.STATIC_DRAW,
});
buffer.vertexArrayDestroyable = false;

// Store the reference point for repeated future use.
attribute.buffer2D = buffer;
attribute.referencePoint2D = referencePoint;
}

export default GeometryPipelineStage;
18 changes: 17 additions & 1 deletion Source/Scene/ModelExperimental/ModelExperimental.js
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Original file line number Diff line number Diff line change
Expand Up @@ -207,9 +207,12 @@ export default function ModelExperimental(options) {
this._featureTableId = undefined;
this._featureTableIdDirty = true;

// Keeps track of resources that need to be destroyed when the Model is destroyed.
// Keeps track of resources that need to be destroyed when the draw commands are reset.
this._resources = [];

// Keeps track of resources that need to be destroyed when the Model is destroyed.
this._modelResources = [];

// Computation of the model's bounding sphere and its initial radius is done in ModelExperimentalSceneGraph
this._boundingSphere = new BoundingSphere();
this._initialRadius = undefined;
Expand Down Expand Up @@ -1462,6 +1465,7 @@ ModelExperimental.prototype.destroy = function () {
}

this.destroyResources();
this.destroyModelResources();

// Only destroy the ClippingPlaneCollection if this is the owner.
const clippingPlaneCollection = this._clippingPlanes;
Expand Down Expand Up @@ -1498,6 +1502,18 @@ ModelExperimental.prototype.destroyResources = function () {
this._resources = [];
};

/**
* Destroys resources generated for the model.
* @private
*/
ModelExperimental.prototype.destroyModelResources = function () {
const resources = this._modelResources;
for (let i = 0; i < resources.length; i++) {
resources[i].destroy();
}
this._modelResources = [];
};

/**
* <p>
* Creates a model from a glTF asset. When the model is ready to render, i.e., when the external binary, image,
Expand Down
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