Voxel Renderer

Repository contains implementation of skeleton animation of voxel models.

Models are represented as Sparse Voxel Octrees with grid size 2048x2048x2048. Renderer uses animated shell meshes to transform rays from word space to voxel space.

First - shell meshes are rasterized, next - for each screen pixel ray transformation is computed and then ray casting in voxel space is used to determine visible voxel. Voxel model remains always in it's bind pose - it is never modified.

In depth description of method will come later.

Watch demo on youtube.

Method works in real time on GTX 750 TI. This demo was captured with screen resolution 1240x720, but it would work in real time even in Full HD.

Building instruction

If you want to use application only with already converted models, build Voxel Renderer application. You need conversion tools only if you want have your own models

Building Voxel Renderer

Repository contains Visual Studio 2015 projects.

To build main application you need to install DirectX SDK.

Installation should define DXSDK_DIR environment variable, which points to SDK directory.

Note that DirectX SDK is deprecated and all libraries were moved to Windows SDK. Maybe I will migrate code to new SDK in future versions.

Included dependencies

All other dependencies are included in repository:

• Autodesk FBX SDK for loading shell meshes.
• Sleeping Wombat Libraries (included as git subtree). Libraries are used to display native window, handle user input and render.
  • swCommonLib
  • swGraphicAPI
  • swInputLibrary
  • swGUI
• RTTR C++ Reflection library (Sleeping Wombat library depends on it)

Building Conversion Tools

To build conversion tools, you must download and compile some libraries:

• liboctree
• My modified fork of ooc_svo_builder library. Original version here.
• My modified fork of trimesh2 library. Original version here.

All libraries should be cloned to folder /External.

Included Dependencies:

• Soil2 for loading textures.
• Templatized C++ Command Line Parser Library
• Autodesk FBX SDK for loading shell meshes.
• swCommonLib
• RTTR C++ Reflection library (Sleeping Wombat library depends on it)

Application usage (VoxelRenderer)

Application can be configured using WorkingDir/StartConfig.config file. For details, check example included in this repository.

Controlling camera

To move camera use standard WASD keys. To turn camera, move mouse with right button pressed.

Moreover you can use these keys to control camera movement:

• Q - step left
• E - step right
• R - step up
• F - step down

Raycasters

There're multiple raycasters implemented which can be configured from StartConfig.config file, for example:

	<Raycaster Type="AnimationRaycasterGPU" />
	<!-- or -->
	<Raycaster Type="GPU Raycaster" />

Most of raycasters are for debugging purposes only. To test application I propose to start with:

• AnimationRaycasterGPU implements animation algorithms.
• GPU Raycaster can display static SVO models.

GPU Raycaster

GPU Raycaster can display static SVOs. Configure octree in StartConfig.config:

<Octree FilePath="Assets/Golem/Golem.voxtree" />

You can choose one of following shaders:

• Key 1 - RaycasterGPU/SimpleColor.hlsl - Displays voxels with colours defined in SVO.
• Key 2 - RaycasterGPU/Normals.hlsl - Displays SVO normal vectors.
• Key 3 - RaycasterGPU/PhongColor.hlsl - Displays SVO with Phong shading. Voxels colours are used as diffuse coefficients.

You can configure light parameters in config:

	<Lights>
		<DirectionalLight Intensity="1.0" >
			<Color X="1.00000" Y="1.00000" Z="1.000"/>
			<Direction X="0.0" Y="0.00000" Z="1.0000"/>			
		</DirectionalLight>
	</Lights>

AnimationRaycasterGPU

AnimationRaycasterGPU implements animation algorithms. To animate model, you must provide .voxtree file with octree to animate and .FBX file to load shell mesh and animations. Configuration in StartConfig.config:

<ShellMesh FilePath="Assets/Dino/Dinosaurus_run.FBX" OctreeFile="Assets/Dino/Dino.voxtree" />

You can choose one of following shaders:

• Key 5 - Shell Mesh transforms rays with inverse animation matrix.
• Key 6 - Shell Mesh transforms rays with change of basis matrix.

Keys from 1 to 4 implement old prototype versions of animation.

Use one of these keys to control animation parameters:

• Numpad Plus (and Minus) - Increase/Decrease shell mesh offset.
• Numpad 8 (and Numpad 2) - Increase/Decrease max aproximation error. (Check in shader what it really does)
• Tab - Enable/Disable shell mesh rendering for rays that didn't hit any voxel on it's path. Pixels for these rays will be painted to grey colour.

Offline Tools

Offline tools can convert .FBX models to .voxtree format. If source files contain textures, conversion scripts will use them to texture voxel model.

Conversion is performed in four steps, because I use external tools to build SVO. That's why the easiest way to convert your own models, is to use WorkingDir/Converters/Convert.py script, that will do whole work for you. To use script you need Python 2.7

Conversion script

This example will build SVO from Minotaur-Idle.FBX file:

python Converters/Convert.py PreBuildAssets\Minotaur\animation\Minotaur-Idle.FBX Assets/Minotaur/Minotaur.voxtree

Note that script created Minotaur-Idle.obj.matlist file in the same directory as .FBX file. Matlist file contains textures information about model. Meshes consist of multiple segments and each can have separate material. For each segment in source model, script writes diffuse texture path to matlist file. Then next scripts can read this file and texture voxel model.

You can provide your own .matlist file and call script like this:

python Converters/Convert.py PreBuildAssets\Minotaur\Minotaur-Idle.FBX Assets/Minotaur/Minotaur.voxtree PreBuildAssets\Minotaur\Minotaur-Idle.obj.matlist

Known issues

Sometimes .FBX files resolves textures paths incorectly and paths in .matlist file point to wrong directories. When this happend, generated voxel model will have default colours. To fix this, you can change path in generated .matlist file and call script for the second time with this changed .matlist file.

FbxToObjConverter

Normally it is recommended to use Conversion script. TODO:

VoxelConverter

Normally it is recommended to use Conversion script. TODO:

Copyright

This software contains Autodesk® FBX® code developed by Autodesk, Inc. Copyright 2014 Autodesk, Inc. All rights, reserved. Such code is provided “as is” and Autodesk, Inc. disclaims any and all warranties, whether express or implied, including without limitation the implied warranties of merchantability, fitness for a particular purpose or non-infringement of third party rights. In no event shall Autodesk, Inc. be liable for any direct, indirect, incidental, special, exemplary, or consequential damages (including, but not limited to, procurement of substitute goods or services; loss of use, data, or profits; or business interruption) however caused and on any theory of liability, whether in contract, strict liability, or tort (including negligence or otherwise) arising in any way out of such code.