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Feature: Travel Costs #1

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5e44e1c
feat: added travel costs to integration step
nathanrun1 Oct 4, 2025
03ec9c6
fix: changed travel costs to only apply to neighbor cost calculation
nathanrun1 Oct 7, 2025
6973ea3
fix: Wasn't properly setting UseTravelCosts on GenerateFlowField comp…
nathanrun1 Oct 8, 2025
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45 changes: 40 additions & 5 deletions Runtime/NativeFlowField.cs
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,7 @@
using System.Diagnostics;
using Unity.Entities;
using Debug = UnityEngine.Debug;
using System.Linq;

namespace FlowFieldAI
{
Expand Down Expand Up @@ -99,6 +100,8 @@ private static class ShaderProperties
public static readonly int Width = Shader.PropertyToID("Width");
public static readonly int Height = Shader.PropertyToID("Height");
public static readonly int DiagonalMovement = Shader.PropertyToID("DiagonalMovement");
public static readonly int UseTravelCosts = Shader.PropertyToID("UseTravelCosts");
public static readonly int TravelCosts = Shader.PropertyToID("TravelCosts");
public static readonly int InputCosts = Shader.PropertyToID("InputCosts");
public static readonly int OutputCosts = Shader.PropertyToID("OutputCosts");
public static readonly int OutputHeatMap = Shader.PropertyToID("OutputHeatMap");
Expand All @@ -108,6 +111,9 @@ private static class ShaderProperties
// ─────────────────────────────────────────────────────────────
// Private Fields
// ─────────────────────────────────────────────────────────────
private ComputeBuffer travelCostsBuffer;
private readonly bool useTravelCosts;

private readonly ComputeShader integrationComputeShader;
private readonly int integrationComputeShaderKernel;
private ComputeBuffer integrationFrontBuffer;
Expand Down Expand Up @@ -148,7 +154,7 @@ private static class ShaderProperties
/// <param name="generateHeatMap">If true, allocates an additional render texture to visualize distance propagation.</param>
/// <param name="minBuffers">Minimum number of buffers to keep pooled.</param>
/// <param name="maxBuffers">Maximum number of buffers allowed for async dispatching.</param>
public NativeFlowField(int width, int height, bool generateHeatMap=false, int minBuffers=2, int maxBuffers=5)
public NativeFlowField(int width, int height, bool generateHeatMap=false, bool useTravelCosts=false, int minBuffers=2, int maxBuffers=5)
{
if (minBuffers < 2)
{
Expand All @@ -165,6 +171,9 @@ public NativeFlowField(int width, int height, bool generateHeatMap=false, int mi

this.generateHeatMap = generateHeatMap;

travelCostsBuffer = new ComputeBuffer(Length, sizeof(float));
this.useTravelCosts = useTravelCosts;

integrationComputeShader = Resources.Load<ComputeShader>("GenerateIntegrationField");
integrationComputeShaderKernel = integrationComputeShader.FindKernel("GenerateIntegrationField");

Expand Down Expand Up @@ -204,6 +213,7 @@ public NativeFlowField(int width, int height, bool generateHeatMap=false, int mi
/// </summary>
public void Dispose()
{
travelCostsBuffer.Dispose();
integrationFrontBuffer.Dispose();
integrationBackBuffer.Dispose();
flowFieldBuffer.Dispose();
Expand All @@ -223,6 +233,18 @@ public void Dispose()
/// <returns>An async GPU readback request that completes when the field is ready.</returns>
public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField) => Bake(inputField, BakeOptions.Default);

/// <summary>
/// Starts a new asynchronous bake using the specified bake options and 0-initialized travel costs.
/// The returned request can be used to track GPU readback completion.
/// </summary>
/// <param name="inputField">
/// A native array representing the input field. Use <see cref="ObstacleCell"/> and <see cref="FreeCell"/> for special cells,
/// and numerical values for target weights.
/// </param>
/// <param name="bakeOptions">Configuration options for this bake operation.</param>
/// <returns>An async GPU readback request that completes when the field is ready.</returns>
public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField, BakeOptions bakeOptions) => Bake(inputField, new NativeArray<float>(), bakeOptions);

/// <summary>
/// Starts a new asynchronous bake using the specified bake options.
/// The returned request can be used to track GPU readback completion.
Expand All @@ -231,13 +253,18 @@ public void Dispose()
/// A native array representing the input field. Use <see cref="ObstacleCell"/> and <see cref="FreeCell"/> for special cells,
/// and numerical values for target weights.
/// </param>
/// <param name="travelCosts">
/// A native array representing the travel costs of each cell in the input field.
/// These costs are added to the minimum weight calculation of each target cell at the same index.
/// </param>
/// <param name="bakeOptions">Configuration options for this bake operation.</param>
/// <returns>An async GPU readback request that completes when the field is ready.</returns>
public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField, BakeOptions bakeOptions)
public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField, NativeArray<float> travelCosts, BakeOptions bakeOptions)
{
bakeTimer.Restart();

ValidateMatrixDimensions(inputField);
if (useTravelCosts) ValidateMatrixDimensions(travelCosts);

if (bufferPool.IsExhausted)
{
Expand All @@ -246,7 +273,7 @@ public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField, BakeOptions b
}

// Initialize buffers
var iterationsThisFrame = InitializeBake(inputField, bakeOptions);
var iterationsThisFrame = InitializeBake(inputField, travelCosts, bakeOptions);

// Generate integration field
PerformIntegration(iterationsThisFrame);
Expand Down Expand Up @@ -284,7 +311,7 @@ public AsyncGPUReadbackRequest Bake(NativeArray<float> inputField, BakeOptions b
// ─────────────────────────────────────────────────────────────
// Private Methods
// ─────────────────────────────────────────────────────────────
private int InitializeBake(NativeArray<float> inputField, BakeOptions bakeOptions)
private int InitializeBake(NativeArray<float> inputField, NativeArray<float> travelCostsField, BakeOptions bakeOptions)
{
// Initialize graphics command buffer
commandBuffer.Clear();
Expand All @@ -308,10 +335,12 @@ private int InitializeBake(NativeArray<float> inputField, BakeOptions bakeOption
? Mathf.Min(iterationsRemaining, bakeOptions.IterationsPerFrame)
: Mathf.Min(iterationsRemaining, bakeOptions.Iterations);

// Initialize compute buffer with input field
// Initialize compute buffer with input field
if (bakeContext.CurrentIteration == 0 && initializeNewBake)
{
commandBuffer.SetBufferData(integrationFrontBuffer, inputField);
if (useTravelCosts)
commandBuffer.SetBufferData(travelCostsBuffer, travelCostsField);
}

return iterationsThisFrame;
Expand All @@ -322,6 +351,10 @@ private void PerformIntegration(int iterationsThisFrame)
commandBuffer.SetComputeIntParam(integrationComputeShader, ShaderProperties.Width, Width);
commandBuffer.SetComputeIntParam(integrationComputeShader, ShaderProperties.Height, Height);
commandBuffer.SetComputeIntParam(integrationComputeShader, ShaderProperties.DiagonalMovement, bakeContext.Options.DiagonalMovement ? 1 : 0);
commandBuffer.SetComputeIntParam(integrationComputeShader, ShaderProperties.UseTravelCosts, useTravelCosts ? 1 : 0);

// Assign travel cost buffer
commandBuffer.SetComputeBufferParam(integrationComputeShader, integrationComputeShaderKernel, ShaderProperties.TravelCosts, travelCostsBuffer);

for (var i = 0; i < iterationsThisFrame; i++)
{
Expand Down Expand Up @@ -356,8 +389,10 @@ private void GenerateFlowField()
commandBuffer.SetComputeIntParam(generateFlowFieldComputeShader, ShaderProperties.Width, Width);
commandBuffer.SetComputeIntParam(generateFlowFieldComputeShader, ShaderProperties.Height, Height);
commandBuffer.SetComputeIntParam(generateFlowFieldComputeShader, ShaderProperties.DiagonalMovement, bakeContext.Options.DiagonalMovement ? 1 : 0);
commandBuffer.SetComputeIntParam(generateFlowFieldComputeShader, ShaderProperties.UseTravelCosts, useTravelCosts ? 1 : 0);
commandBuffer.SetComputeBufferParam(generateFlowFieldComputeShader, generateFlowFieldComputeShaderKernel, ShaderProperties.InputCosts, integrationFrontBuffer);
commandBuffer.SetComputeBufferParam(generateFlowFieldComputeShader, generateFlowFieldComputeShaderKernel, ShaderProperties.OutputFlowField, flowFieldBuffer);
commandBuffer.SetComputeBufferParam(generateFlowFieldComputeShader, generateFlowFieldComputeShaderKernel, ShaderProperties.TravelCosts, travelCostsBuffer);
commandBuffer.DispatchCompute(generateFlowFieldComputeShader, generateFlowFieldComputeShaderKernel, threadGroupsX, threadGroupsY, 1);

Graphics.ExecuteCommandBufferAsync(commandBuffer, bakeContext.Options.ComputeQueueType);
Expand Down
7 changes: 6 additions & 1 deletion Runtime/Resources/GenerateFlowField.compute
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@
uint Width;
uint Height;
int DiagonalMovement;
int UseTravelCosts;
StructuredBuffer<float> TravelCosts;
StructuredBuffer<float> InputCosts;
RWStructuredBuffer<int> OutputFlowField;

Expand Down Expand Up @@ -35,7 +37,10 @@ int getFlow(uint x, uint y)
if (InputCosts[flatten(x, y + offsets[i].y, Width)] >= FLT_MAX-1) continue;
}
uint neighborIndex = flatten(nx, ny, Width);
float neighborCost = InputCosts[neighborIndex];
float neighborCost;

if (UseTravelCosts) neighborCost = InputCosts[neighborIndex] + TravelCosts[neighborIndex]; // Add travel cost
else neighborCost = InputCosts[neighborIndex];

if (neighborCost < FLT_MAX && neighborCost > FLT_MIN)
{
Expand Down
13 changes: 10 additions & 3 deletions Runtime/Resources/GenerateIntegrationField.compute
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Original file line number Diff line number Diff line change
Expand Up @@ -5,6 +5,8 @@
uint Width;
uint Height;
int DiagonalMovement;
int UseTravelCosts;
StructuredBuffer<float> TravelCosts;
StructuredBuffer<float> InputCosts;
RWStructuredBuffer<float> OutputCosts;

Expand All @@ -29,11 +31,16 @@ float getMinCost(uint x, uint y)
if (isDiagonal)
{
// Both orthogonal must be free
if (InputCosts[flatten(x + offsets[i].x, y, Width)] >= FLT_MAX-1) continue;
if (InputCosts[flatten(x, y + offsets[i].y, Width)] >= FLT_MAX-1) continue;
if (InputCosts[flatten(x + offsets[i].x, y, Width)] >= FLT_MAX - 1)
continue;
if (InputCosts[flatten(x, y + offsets[i].y, Width)] >= FLT_MAX - 1)
continue;
}
uint neighborIndex = flatten(nx, ny, Width);
float neighborCost = InputCosts[neighborIndex];

float neighborCost;
if (UseTravelCosts) neighborCost = InputCosts[neighborIndex] + TravelCosts[neighborIndex]; // Add travel cost
else neighborCost = InputCosts[neighborIndex];

if (neighborCost < FLT_MAX && neighborCost > FLT_MIN)
{
Expand Down