Tessellation Class Reference

Implementation of tessellation, abstract class. More...

#include <tessellation.hpp>

Inheritance diagram for Tessellation:

Public Member Functions
	Tessellation (const std::string &name, Scene *scene=0, Model *model=0, const glm::mat4 &modelMatrix=glm::mat4(1))
virtual	~Tessellation ()
void	draw () const
bool	animate (double time)
void	update (double deltaT)
void	setShader (Shader *val)
GLuint	getDispTexture () const
unsigned int	getTessLevelIn () const
unsigned int	getTessLevelOut () const
void	setTessLevelIn (unsigned int val)
void	setTessLevelOut (unsigned int val)
Public Member Functions inherited from SceneObject
	SceneObject (std::shared_ptr< SceneObject > &effectParent, const glm::mat4 &modelMatrix=glm::mat4(1))
	SceneObject (const std::string &name, Scene *scene=0, Model *model=0, const glm::mat4 &modelMatrix=glm::mat4(1))
virtual	~SceneObject ()
Model *	getModel () const
Shader *	getShader () const
glm::mat4	getModelMatrix () const
glm::mat4	getGlobalModelMatrix () const
std::string	getName () const
std::shared_ptr< SceneObject >	getParent () const
void	setAnimationTime (double time)
bool	setAnimation (const Animation &anim)
bool	delChild (size_t idx)
bool	getChild (size_t idx, std::shared_ptr< SceneObject > &child) const
bool	addChild (std::shared_ptr< SceneObject > &child)
bool	remEffect (const std::string &name)
SceneObject *	getEffect (const std::string &name) const
bool	addEffect (const std::string &name, std::unique_ptr< SceneObject > &effect)
bool	doNotRender ()
bool	getIsVolSun ()
virtual void	reset ()

Protected Attributes
GLuint	dispTexture
unsigned int	tessLevelIn
unsigned int	tessLevelOut
Protected Attributes inherited from SceneObject
GLuint	vao
Scene *	scene
Model *	model
Shader *	shader
glm::mat4	modelMatrix
std::string	name
std::weak_ptr< SceneObject >	parent
std::vector< std::shared_ptr< SceneObject > >	childs
std::map< std::string, std::unique_ptr< SceneObject > >	effectChilds
size_t	animIDX
Animation	animation
bool	norender
bool	isVolSun

Private Attributes
float	dispTime

Additional Inherited Members
Public Types inherited from SceneObject
typedef std::vector< std::pair< double, glm::mat4 > >	Animation

Detailed Description

Implementation of tessellation, abstract class.

Author

Adam

For the rendering of animated flying bullets effect, tessellation was implemented using the Tessellation Shader. Since this effect is part of the GPU Particle System, this section will have some references on particles. The Vertex Shader is only a pass-through shader. In the Tessellation Control Shader, the inner and outer tessellation level can be set. The visualization of this two variable on triangles can be see on following image:

StackOverflow - Tessellation Shader - OpenGL

Using the life of a particle, the vertices of the object are scaled. For this purpose, level-of-detail is used, where larger objects will have more vertices generated. The value of tessellation levels are computed using the life of a particle. The effect uses triangles to tessellate, therefore Barycentric coordinates are received in the Tessellation Evaluation Shader. The vertices are computed by interpolating the Barycentric coordinates of the tessellated values with the control points. Then they are normalized to transform the cube model into a sphere. If quads would be tessellated, interpolation would be necessary only for normals. Displacement mapping is used in order to modify the shape of the sphere. To achieve a simple animation a 3D texture is used, which stores layers of Gaussian functions with increasing sigma value. The coordinates of the texture is the usual u, v and the third coordinate is the life of the particle. The positions are translated along the normal in local space to achieve displacement. To improve the normals of the displaced surface a Geometry Shader is used, where the tessellated normals are interpolated with the normal of the face, where the normal of the face is the cross product of two vectors computed from the displaced vertices. Finally the Fragment Shader of the OmniShadow effect is used. To achieve shadows with OmniShadow, only a simplified Tessellation Evaluation Shader is necessary for rendering the tessellation effect within the OmniShadow effect.

See also

https://www.opengl.org/wiki/Tessellation

Constructor & Destructor Documentation

Tessellation::Tessellation	(	const std::string &	name,
		Scene *	scene = 0,
		Model *	model = 0,
		const glm::mat4 &	modelMatrix = glm::mat4(1)
	)

Tessellation::~Tessellation ( )

virtual

Member Function Documentation

bool Tessellation::animate ( double  time )

virtual

Reimplemented from SceneObject.

void Tessellation::draw ( ) const

virtual

Reimplemented from SceneObject.

GLuint Tessellation::getDispTexture ( ) const

inline

unsigned int Tessellation::getTessLevelIn ( ) const

inline

unsigned int Tessellation::getTessLevelOut ( ) const

inline

void Tessellation::setShader ( Shader *  val )

virtual

Reimplemented from SceneObject.

void Tessellation::setTessLevelIn ( unsigned int  val )

inline

void Tessellation::setTessLevelOut ( unsigned int  val )

inline

void Tessellation::update ( double  deltaT )

virtual

Reimplemented from SceneObject.

Member Data Documentation

GLuint Tessellation::dispTexture

protected

Displacement texture.

float Tessellation::dispTime

private

Global animation time.

unsigned int Tessellation::tessLevelIn

protected

Inner tessellation level.

unsigned int Tessellation::tessLevelOut

protected

Outer tessellation level.

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The documentation for this class was generated from the following files:

• C:/Users/FLx/Selektron/include/tessellation.hpp
• C:/Users/FLx/Selektron/src/tessellation.cpp