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Reuse Ellipse element buffers to reduce memory use (NASAWorldWind#208)
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* Add element buffer cache

* Fix element buffer cache

* Store element buffer in render resource cache

* Refactor buffer retrieval from cache

* Refactor buffer retrieval and reassembly

* Rename assembly function

* Rename variables

* Simplify buffer retrieval logic

* Switch to Range object for managing buffer indices

* Fix spelling of function assembleElementsToCache function
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@zglueck @pdavidc
zglueck authored and pdavidc committed Jan 18, 2018
1 parent faa6eb0 commit 120f46a
Showing 1 changed file with 80 additions and 45 deletions.
125 changes: 80 additions & 45 deletions worldwind/src/main/java/gov/nasa/worldwind/shape/Ellipse.java
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Original file line number Diff line number Diff line change
Expand Up @@ -6,6 +6,7 @@
package gov.nasa.worldwind.shape;

import android.opengl.GLES20;
import android.util.SparseArray;

import java.nio.ByteBuffer;
import java.nio.ByteOrder;
Expand All @@ -15,6 +16,7 @@
import gov.nasa.worldwind.draw.DrawShapeState;
import gov.nasa.worldwind.draw.DrawableSurfaceShape;
import gov.nasa.worldwind.geom.Position;
import gov.nasa.worldwind.geom.Range;
import gov.nasa.worldwind.geom.Vec3;
import gov.nasa.worldwind.render.BasicShaderProgram;
import gov.nasa.worldwind.render.BufferObject;
Expand Down Expand Up @@ -102,13 +104,9 @@ public class Ellipse extends AbstractShape {

protected FloatArray vertexArray = new FloatArray();

protected ShortArray interiorElements = new ShortArray();

protected ShortArray outlineElements = new ShortArray();

protected Object vertexBufferKey = nextCacheKey();

protected Object elementBufferKey = nextCacheKey();
protected static SparseArray<ElementBufferAttributes> ELEMENT_BUFFER_ATTRIBUTES = new SparseArray<>();

protected Vec3 vertexOrigin = new Vec3();

Expand Down Expand Up @@ -383,9 +381,7 @@ protected void makeDrawable(RenderContext rc) {

if (this.mustAssembleGeometry(rc)) {
this.assembleGeometry(rc);
this.assembleElements(rc);
this.vertexBufferKey = nextCacheKey();
this.elementBufferKey = nextCacheKey();
}

// Obtain a drawable form the render context pool.
Expand All @@ -412,19 +408,16 @@ protected void makeDrawable(RenderContext rc) {
rc.putBufferObject(this.vertexBufferKey, drawState.vertexBuffer);
}

// Assemble the drawable's OpenGL element buffer object.
drawState.elementBuffer = rc.getBufferObject(this.elementBufferKey);
// Get the attributes of the element buffer
ElementBufferAttributes elementBufferAttributes = ELEMENT_BUFFER_ATTRIBUTES.get(this.intervals);
drawState.elementBuffer = rc.getBufferObject(elementBufferAttributes);
if (drawState.elementBuffer == null) {
int size = (this.interiorElements.size() * 2) + (this.outlineElements.size() * 2);
ShortBuffer buffer = ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder()).asShortBuffer();
buffer.put(this.interiorElements.array(), 0, this.interiorElements.size());
buffer.put(this.outlineElements.array(), 0, this.outlineElements.size());
drawState.elementBuffer = new BufferObject(GLES20.GL_ELEMENT_ARRAY_BUFFER, size, buffer.rewind());
rc.putBufferObject(this.elementBufferKey, drawState.elementBuffer);
elementBufferAttributes = assembleElementsToCache(rc, this.intervals);
drawState.elementBuffer = rc.getBufferObject(elementBufferAttributes);
}

this.drawInterior(rc, drawState);
this.drawOutline(rc, drawState);
this.drawInterior(rc, drawState, elementBufferAttributes);
this.drawOutline(rc, drawState, elementBufferAttributes);

// Configure the drawable according to the shape's attributes.
drawState.vertexOrigin.set(this.vertexOrigin);
Expand All @@ -436,7 +429,7 @@ protected void makeDrawable(RenderContext rc) {
rc.offerSurfaceDrawable(drawable, 0 /*zOrder*/);
}

protected void drawInterior(RenderContext rc, DrawShapeState drawState) {
protected void drawInterior(RenderContext rc, DrawShapeState drawState, ElementBufferAttributes elementBufferAttrs) {
if (!this.activeAttributes.drawInterior) {
return;
}
Expand All @@ -446,11 +439,11 @@ protected void drawInterior(RenderContext rc, DrawShapeState drawState) {
// Configure the drawable to display the shape's interior.
drawState.color(rc.pickMode ? this.pickColor : this.activeAttributes.interiorColor);
drawState.texCoordAttrib(2 /*size*/, 12 /*offset in bytes*/);
drawState.drawElements(GLES20.GL_TRIANGLE_STRIP, this.interiorElements.size(),
GLES20.GL_UNSIGNED_SHORT, 0 /*offset*/);
drawState.drawElements(GLES20.GL_TRIANGLE_STRIP, elementBufferAttrs.interiorElements.length(),
GLES20.GL_UNSIGNED_SHORT, elementBufferAttrs.interiorElements.lower * 2 /*offset*/);
}

protected void drawOutline(RenderContext rc, DrawShapeState drawState) {
protected void drawOutline(RenderContext rc, DrawShapeState drawState, ElementBufferAttributes elementBufferAttrs) {
if (!this.activeAttributes.drawOutline) {
return;
}
Expand All @@ -461,8 +454,8 @@ protected void drawOutline(RenderContext rc, DrawShapeState drawState) {
drawState.color(rc.pickMode ? this.pickColor : this.activeAttributes.outlineColor);
drawState.lineWidth(this.activeAttributes.outlineWidth);
drawState.texCoordAttrib(1 /*size*/, 20 /*offset in bytes*/);
drawState.drawElements(GLES20.GL_LINE_LOOP, this.outlineElements.size(),
GLES20.GL_UNSIGNED_SHORT, this.interiorElements.size() * 2 /*offset*/);
drawState.drawElements(GLES20.GL_LINE_LOOP, elementBufferAttrs.outlineElements.length(),
GLES20.GL_UNSIGNED_SHORT, elementBufferAttrs.outlineElements.lower * 2 /*offset*/);
}

protected boolean mustAssembleGeometry(RenderContext rc) {
Expand All @@ -477,11 +470,8 @@ protected boolean mustAssembleGeometry(RenderContext rc) {
}

protected void assembleGeometry(RenderContext rc) {
// Clear the shape's vertex array and element arrays. These arrays will accumulate values as the shapes's
// geometry is assembled.
// Clear the shape's vertex array. The array will accumulate values as the shapes's geometry is assembled.
this.vertexArray.clear();
this.interiorElements.clear();
this.outlineElements.clear();

// Use the ellipse's center position as the local origin for vertex positions.
this.vertexOrigin.set(this.center.longitude, this.center.latitude, this.center.altitude);
Expand Down Expand Up @@ -537,39 +527,61 @@ protected void assembleGeometry(RenderContext rc) {
this.boundingBox.setToUnitBox(); // Surface/geographic shape bounding box is unused
}

protected void assembleElements(RenderContext rc) {
protected static ElementBufferAttributes assembleElementsToCache(RenderContext rc, int intervals) {
// Create temporary storage for elements
ShortArray interiorElements = new ShortArray();
ShortArray outlineElements = new ShortArray();

// Generate the interior element buffer with spine
int interiorIdx = this.intervals;
int interiorIdx = intervals;
// Add the anchor leg
this.interiorElements.add((short) 0);
this.interiorElements.add((short) 1);
interiorElements.add((short) 0);
interiorElements.add((short) 1);
// Tessellate the interior
for (int i = 2; i < this.intervals; i++) {
for (int i = 2; i < intervals; i++) {
// Add the corresponding interior spine point if this isn't the vertex following the last vertex for the
// negative major axis
if (i != (this.intervals / 2 + 1)) {
if (i > this.intervals / 2) {
this.interiorElements.add((short) --interiorIdx);
if (i != (intervals / 2 + 1)) {
if (i > intervals / 2) {
interiorElements.add((short) --interiorIdx);
} else {
this.interiorElements.add((short) interiorIdx++);
interiorElements.add((short) interiorIdx++);
}
}
// Add the degenerate triangle at the negative major axis in order to flip the triangle strip back towards
// the positive axis
if (i == this.intervals / 2) {
this.interiorElements.add((short) i);
if (i == intervals / 2) {
interiorElements.add((short) i);
}
// Add the exterior vertex
this.interiorElements.add((short) i);
interiorElements.add((short) i);
}
// Complete the strip
this.interiorElements.add((short) --interiorIdx);
this.interiorElements.add((short) 0);
interiorElements.add((short) --interiorIdx);
interiorElements.add((short) 0);

// Generate the outline element buffer
for (int i = 0; i < this.intervals; i++) {
this.outlineElements.add((short) i);
for (int i = 0; i < intervals; i++) {
outlineElements.add((short) i);
}

// Generate an attribute bundle for this element buffer
ElementBufferAttributes elementBufferAttributes = new ElementBufferAttributes();
elementBufferAttributes.interiorElements.set(0, interiorElements.size());
elementBufferAttributes.outlineElements.set(interiorElements.size(), interiorElements.size() + outlineElements.size());

// Generate a buffer for the element
int size = (interiorElements.size() * 2) + (outlineElements.size() * 2);
ShortBuffer buffer = ByteBuffer.allocateDirect(size).order(ByteOrder.nativeOrder()).asShortBuffer();
buffer.put(interiorElements.array(), 0, interiorElements.size());
buffer.put(outlineElements.array(), 0, outlineElements.size());
BufferObject elementBuffer = new BufferObject(GLES20.GL_ELEMENT_ARRAY_BUFFER, size, buffer.rewind());

// Cache the buffer object and attributes in the render resource cache and attribute map respectively
rc.putBufferObject(elementBufferAttributes, elementBuffer);
ELEMENT_BUFFER_ATTRIBUTES.put(intervals, elementBufferAttributes);

return elementBufferAttributes;
}

protected void addVertex(RenderContext rc, double latitude, double longitude, double altitude) {
Expand Down Expand Up @@ -625,7 +637,30 @@ protected double computeCircumference() {
@Override
protected void reset() {
this.vertexArray.clear();
this.interiorElements.clear();
this.outlineElements.clear();
}

protected static class ElementBufferAttributes {

protected Range interiorElements = new Range();

protected Range outlineElements = new Range();

@Override
public boolean equals(Object o) {
if (this == o) return true;
if (o == null || getClass() != o.getClass()) return false;

ElementBufferAttributes that = (ElementBufferAttributes) o;

if (!interiorElements.equals(that.interiorElements)) return false;
return outlineElements.equals(that.outlineElements);
}

@Override
public int hashCode() {
int result = interiorElements.hashCode();
result = 31 * result + outlineElements.hashCode();
return result;
}
}
}

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