Simple C++ implementation of skeletal animation and software skinning
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README.md

Skeletal Animation and Software Skinning

The aim of this project is to provide simple skeletal animation and software skinning (on the CPU) in C++.

This project can be used by developers who want to quickly add simple animations to their project. For commercial software this project may be... lacking... but can be used as a base to improve upon.

Features

Feature Yes No Notes
Model Loading V By using Assimp
Skeletal Animation V
Vertex Animation X
Rendering X
CPU Skinning V
GPU Skinning X
Skinned Vertices V
Skinned Normals X To do
Materials X To do
Textures X To do
Multi-threaded X Will maybe add
Highly Optimized X

Dependencies

The SkeletalAnimation project is only dependent on GLM.

The AssimpConverter project is dependent on Assimp and SkeletalAnimation.

In order to compile the projects, both project files need to be modified to use the include files, and link with their respective dependencies.

Usage

Make sure your project links with SkeletalAnimation.lib, or compile SkeletalModel.cpp into your project.

Loading

If you do not have your own model loader you can use Assimp to load a model and use AssimpConverter to convert it to a SkeletalModel that can be rendered and animated:

void LoadModel()
{
	Assimp::Importer Importer;
	const aiScene* pScene = Importer.ReadFile("some_animated_model.fbx",
		aiProcess_LimitBoneWeights |
		aiProcess_Triangulate |
		aiProcess_JoinIdenticalVertices |
		aiProcess_SortByPType);

	AssimpConverter::Convert(pScene, g_AnimatedModel);
}

Animating

After the SkeletalModel has been loaded it needs to be updated every frame to make it animate:

void Update(float a_Dt) // a_Dt is the elapsed time since last frame in seconds
{
  g_AnimatedModel.Update(a_Dt);
}

Rendering

Here is some (very crude) example code to demonstrate how to render the animated model using OpenGL:

void Render()
{
	for (unsigned int i = 0; i < g_AnimatedModel.GetNumMeshes(); ++i)
	{
		const SA::sAnimatedMesh& AnimMesh = g_AnimatedModel.GetMesh(i);

		glBegin(GL_TRIANGLES);
		for (unsigned int i = 0; i < AnimMesh.NumIndices; ++i)
		{
			unsigned int Index = AnimMesh.pIndices[i];
			glm::vec3 n = AnimMesh.pNormals[Index];
			glm::vec3 v = AnimMesh.pTransformedVertices[Index];
			
			glColor4f(n.x, n.y, n.z, 1);
			glVertex3f(v.x, v.y, v.z);
		}
		glEnd();
	}
}

References

http://ogldev.atspace.co.uk/www/tutorial38/tutorial38.html