C# Class Sparrow.Utils.VertexData

The VertexData class manages a raw list of vertex information, allowing direct upload to OpenGL vertex buffers. _You only have to work with this class if you create display objects with a custom render function. If you don't plan to do that, you can safely ignore it._ To render objects with OpenGL, you have to organize vertex data in so-called vertex buffers. Those buffers reside in graphics memory and can be accessed very efficiently by the GPU. Before you can move data into vertex buffers, you have to set it up in conventional memory - that is, in a byte array. That array contains all vertex information (the coordinates, color, and texture coordinates) - one vertex after the other. To simplify creating and working with such a bulky list, the VertexData class was created. It contains methods to specify and modify vertex data. The raw array managed by the class can then easily be uploaded to a vertex buffer. **Premultiplied Alpha** The color values of texture files may contain premultiplied alpha values, which means that the 'RGB' values were multiplied with the 'alpha' value before saving them. On rendering, it makes a difference in which way the alpha value is saved; for that reason, the VertexData class mimics this behavior. You can choose how the alpha values should be handled via the 'premultipliedAlpha' property.

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Public Methods

Method	Description
AlphaAt ( int index ) : float	Returns the alpha value of a vertex.
BoundsAfterTransformation ( Matrix matrix ) : Rectangle	Calculates the bounding rectangle of all vertices after being transformed by a matrix.
BoundsAfterTransformation ( Matrix matrix, int atIndex, int numVertices ) : Rectangle	Calculates the bounding rectangle of subsequent vertices after being transformed by a matrix.
ColorAt ( int index ) : uint	Returns the RGB color of a vertex (without premultiplied alpha).
CopyToVertexData ( VertexData target, bool copyColor, int atIndex ) : void	Copies the vertex data of this instance to another vertex data object, starting at a certain index.
CopyToVertexData ( VertexData target, bool copyColor, int atIndex, int numVertices ) : void	Copies a range of vertices of this instance to another vertex data object.
PositionAt ( int index ) : Point	Returns the position of a vertex.
ScaleAlphaBy ( float factor ) : void	Multiplies all alpha values with a certain factor.
ScaleAlphaBy ( float factor, int index, int numVertices ) : void	Multiplies a range of alpha values with a certain factor.
SetAlpha ( float alpha ) : void	Updates the alpha value of all vertices.
SetAlpha ( float alpha, int atIndex ) : void	Updates the alpha value of a vertex.
SetColor ( uint color ) : void	Updates the color of all vertexes. The method always expects non-premultiplied alpha values.
SetColor ( uint color, float alpha ) : void	Updates the color of all vertexes. The method always expects non-premultiplied alpha values.
SetColor ( uint color, float alpha, int atIndex ) : void	Updates the color of a vertex. The method always expects non-premultiplied alpha values.
SetColor ( uint color, int atIndex ) : void	Updates the color of a vertex. The method always expects non-premultiplied alpha values.
SetPosition ( Point position, int atIndex ) : void	Updates the position of a vertex.
SetPosition ( float x, float y, int atIndex ) : void	Updates the position of a vertex.
SetPremultipliedAlpha ( bool value, bool updateVertices ) : void	Changes the way alpha and color values are stored. Optionally, all exisiting vertices are updated.
SetTexCoords ( Point texCoords, int atIndex ) : void	Updates the texture coordinates of a vertex.
SetTexCoords ( float x, float y, int atIndex ) : void	Updates the texture coordinates of a vertex.
TexCoordsAt ( int index ) : Point	Returns the texture coordinates of a vertex.
TransformVertices ( Matrix matrix, int atIndex, int numVertices ) : void	Transforms the positions of subsequent vertices by multiplication with a transformation matrix
VertexData ( int numVertices, bool premultipliedAlpha = false ) : System	Initializes a VertexData instance with a certain size.

Method Details

AlphaAt() public method

Returns the alpha value of a vertex.

public AlphaAt ( int index ) : float
index	int
return	float

BoundsAfterTransformation() public method

Calculates the bounding rectangle of all vertices after being transformed by a matrix.

public BoundsAfterTransformation ( Matrix matrix ) : Rectangle
matrix	Matrix
return	Sparrow.Geom.Rectangle

BoundsAfterTransformation() public method

Calculates the bounding rectangle of subsequent vertices after being transformed by a matrix.

public BoundsAfterTransformation ( Matrix matrix, int atIndex, int numVertices ) : Rectangle
matrix	Matrix
atIndex	int
numVertices	int
return	Sparrow.Geom.Rectangle

ColorAt() public method

Returns the RGB color of a vertex (without premultiplied alpha).

public ColorAt ( int index ) : uint
index	int
return	uint

CopyToVertexData() public method

Copies the vertex data of this instance to another vertex data object, starting at a certain index.

public CopyToVertexData ( VertexData target, bool copyColor, int atIndex ) : void
target	VertexData
copyColor	bool
atIndex	int
return	void

CopyToVertexData() public method

Copies a range of vertices of this instance to another vertex data object.

public CopyToVertexData ( VertexData target, bool copyColor, int atIndex, int numVertices ) : void
target	VertexData
copyColor	bool
atIndex	int
numVertices	int
return	void

PositionAt() public method

Returns the position of a vertex.

public PositionAt ( int index ) : Point
index	int
return	Point

ScaleAlphaBy() public method

Multiplies all alpha values with a certain factor.

public ScaleAlphaBy ( float factor ) : void
factor	float
return	void

ScaleAlphaBy() public method

Multiplies a range of alpha values with a certain factor.

public ScaleAlphaBy ( float factor, int index, int numVertices ) : void
factor	float
index	int
numVertices	int
return	void

SetAlpha() public method

Updates the alpha value of all vertices.

public SetAlpha ( float alpha ) : void
alpha	float
return	void

SetAlpha() public method

Updates the alpha value of a vertex.

public SetAlpha ( float alpha, int atIndex ) : void
alpha	float
atIndex	int
return	void

SetColor() public method

Updates the color of all vertexes. The method always expects non-premultiplied alpha values.

public SetColor ( uint color ) : void
color	uint
return	void

SetColor() public method

Updates the color of all vertexes. The method always expects non-premultiplied alpha values.

public SetColor ( uint color, float alpha ) : void
color	uint
alpha	float
return	void

SetColor() public method

Updates the color of a vertex. The method always expects non-premultiplied alpha values.

public SetColor ( uint color, float alpha, int atIndex ) : void
color	uint
alpha	float
atIndex	int
return	void

SetColor() public method

Updates the color of a vertex. The method always expects non-premultiplied alpha values.

public SetColor ( uint color, int atIndex ) : void
color	uint
atIndex	int
return	void

SetPosition() public method

Updates the position of a vertex.

public SetPosition ( Point position, int atIndex ) : void
position	Point
atIndex	int
return	void

SetPosition() public method

Updates the position of a vertex.

public SetPosition ( float x, float y, int atIndex ) : void
x	float
y	float
atIndex	int
return	void

SetPremultipliedAlpha() public method

Changes the way alpha and color values are stored. Optionally, all exisiting vertices are updated.

public SetPremultipliedAlpha ( bool value, bool updateVertices ) : void
value	bool
updateVertices	bool
return	void

SetTexCoords() public method

Updates the texture coordinates of a vertex.

public SetTexCoords ( Point texCoords, int atIndex ) : void
texCoords	Point
atIndex	int
return	void

SetTexCoords() public method

Updates the texture coordinates of a vertex.

public SetTexCoords ( float x, float y, int atIndex ) : void
x	float
y	float
atIndex	int
return	void

TexCoordsAt() public method

Returns the texture coordinates of a vertex.

public TexCoordsAt ( int index ) : Point
index	int
return	Point

TransformVertices() public method

Transforms the positions of subsequent vertices by multiplication with a transformation matrix

public TransformVertices ( Matrix matrix, int atIndex, int numVertices ) : void
matrix	Matrix
atIndex	int
numVertices	int
return	void

VertexData() public method

Initializes a VertexData instance with a certain size.

public VertexData ( int numVertices, bool premultipliedAlpha = false ) : System
numVertices	int
premultipliedAlpha	bool
return	System