Game Development Reference

In-Depth Information

1

VI

Bit-Trail Traversal for Stackless

LBVH on DirectCompute

Sergio Murgu ıa, Francisco Avila,

Leo Reyes, and Arturo Garc ıa

1.1

Introduction

Rendering dynamic scenes with ray tracing is a major challenge on current hard-

ware and software implementations. Fast construction algorithms are usually

needed to rebuild acceleration structures from scratch on each frame in current

state-of-the-art implementations. However, thesealgorithmstendtohavepoor

traversal performance.

This article describes an improvement to the stackless linear bounding vol-

ume hierarchy (SLBVH) presented in [Murguia et al. 11], which is a new way

for traversing and constructing a linear bounding volume hierarchy (LBVH). The

SLBVH enables dynamic scenes relying on a fast construction algorithm while

maintaining traversal performance for real-time ray tracing. Furthermore, a naive

Monte Carlo algorithm allows the framework to produce high-quality global illu-

mination effects.

The current implementation is the continuation of the chapter “Interactive

Ray Tracing Using the Compute Shader on DirectX 11” published in
GPU Pro

3
[Garcia et al. 12]. The core of this new chapter is the heap-based structure.

The main contributions of the article are

1. a tutorial on how to implement a SLBVH running solely on the GPU using

DirectCompute and DirectX 11;

2. a stackless binary heap as an LBVH, reducing memory accesses while main-

taining traversal performance;

3. four arithmetic operations that compute the left, right, parent, and next-

to-visit nodes (which depend on the direction of the ray);

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