geometry

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 Go to latest Published: Oct 24, 2020 License: BSD-2-Clause Imports: 6 Imported by: 0

Documentation

Overview

Package geometry implements several primitive geometry generators.

Index

Constants

View Source 
const MaxActiveMorphTargets = 8

MaxActiveMorphTargets is the maximum number of active morph targets.

Variables

This section is empty.

Functions

This section is empty.

Types

type Box 

type Box struct {
	Geometry
	Width          float32
	Height         float32
	Length         float32
	WidthSegments  int // > 0
	HeightSegments int // > 0
	LengthSegments int // > 0
}

Box represents the geometry of a rectangular cuboid. See https://en.wikipedia.org/wiki/Cuboid#Rectangular_cuboid for more details. A Box geometry is defined by its width, height, and length and also by the number of segments in each dimension.

func NewBox 

func NewBox(width, height, length float32) *Box

NewBox creates a box geometry of the specified width, height, and length.

func NewCube 

func NewCube(size float32) *Box

NewCube creates a new cube geometry of the specified size.

func NewSegmentedBox 

func NewSegmentedBox(width, height, length float32, widthSegments, heightSegments, lengthSegments int) *Box

NewSegmentedBox creates a box geometry of the specified size and with the specified number of segments in each dimension. This is the Box constructor with most tunable parameters.

func NewSegmentedCube 

func NewSegmentedCube(size float32, segments int) *Box

NewSegmentedCube creates a cube geometry of the specified size and number of segments.

type Circle 

type Circle struct {
	Geometry
	Radius      float64
	Segments    int // >= 3
	ThetaStart  float64
	ThetaLength float64
}

Circle represents the geometry of a filled circle (i.e. a disk) The center of the circle is at the origin, and theta runs counter-clockwise on the XY plane, starting at (x,y,z)=(1,0,0).

func NewCircle 

func NewCircle(radius float64, segments int) *Circle

NewCircle creates a new circle geometry with the specified radius and number of radial segments/triangles (minimum 3).

func NewCircleSector 

func NewCircleSector(radius float64, segments int, thetaStart, thetaLength float64) *Circle

NewCircleSector creates a new circle or circular sector geometry with the specified radius, number of radial segments/triangles (minimum 3), sector start angle in radians (thetaStart), and sector size angle in radians (thetaLength). This is the Circle constructor with most tunable parameters.

type Cylinder 

type Cylinder struct {
	Geometry
	RadiusTop      float64
	RadiusBottom   float64
	Height         float64
	RadialSegments int
	HeightSegments int
	ThetaStart     float64
	ThetaLength    float64
	Top            bool
	Bottom         bool
}

Cylinder represents a cylinder geometry

func NewCylinder 

func NewCylinder(radiusTop, radiusBottom, height float64,
	radialSegments, heightSegments int,
	thetaStart, thetaLength float64, top, bottom bool) *Cylinder

NewCylinder creates and returns a pointer to a new Cylinder geometry object.

type Geometry 

type Geometry struct {
	ShaderDefines gls.ShaderDefines // Geometry-specific shader defines
	// contains filtered or unexported fields
}

Geometry encapsulates a three-dimensional vertex-based geometry.

func NewGeometry 

func NewGeometry() *Geometry

NewGeometry creates and returns a pointer to a new Geometry.

func (*Geometry) AddGroup 

func (g *Geometry) AddGroup(start, count, matIndex int) *Group

AddGroup adds a geometry group (for multimaterial).

func (*Geometry) AddGroupList 

func (g *Geometry) AddGroupList(groups []Group)

AddGroupList adds the specified list of groups to this geometry.

func (*Geometry) AddVBO 

func (g *Geometry) AddVBO(vbo *gls.VBO)

AddVBO adds a Vertex Buffer Object for this geometry.

func (*Geometry) ApplyMatrix 

func (g *Geometry) ApplyMatrix(m *math32.Matrix4)

ApplyMatrix multiplies each of the geometry position vertices by the specified matrix and apply the correspondent normal transform matrix to the geometry normal vectors. The geometry's bounding box and sphere are recomputed if needed.

func (*Geometry) Area 

func (g *Geometry) Area() float32

Area returns the surface area. NOTE: This only works for triangle-based meshes.

func (*Geometry) AttributeName 

func (g *Geometry) AttributeName(atype gls.AttribType) string

AttributeName returns the name of the VBO attribute associated with the provided attribute type.

func (*Geometry) BoundingBox 

func (g *Geometry) BoundingBox() math32.Box3

BoundingBox computes the bounding box of the geometry if necessary and returns is value.

func (*Geometry) BoundingSphere 

func (g *Geometry) BoundingSphere() math32.Sphere

BoundingSphere computes the bounding sphere of this geometry if necessary and returns its value.

func (*Geometry) Dispose 

func (g *Geometry) Dispose()

Dispose decrements this geometry reference count and if possible releases OpenGL resources, C memory and VBOs associated with this geometry.

func (*Geometry) GetGeometry 

func (g *Geometry) GetGeometry() *Geometry

GetGeometry satisfies the IGeometry interface.

func (*Geometry) GroupAt 

func (g *Geometry) GroupAt(idx int) *Group

GroupAt returns pointer to geometry group at the specified index.

func (*Geometry) GroupCount 

func (g *Geometry) GroupCount() int

GroupCount returns the number of geometry groups (for multimaterial).

func (*Geometry) Incref 

func (g *Geometry) Incref() *Geometry

Incref increments the reference count for this geometry and returns a pointer to the geometry. It should be used when this geometry is shared by another Graphic object.

func (*Geometry) Indexed 

func (g *Geometry) Indexed() bool

Indexed returns whether the geometry is indexed or not.

func (*Geometry) Indices 

func (g *Geometry) Indices() math32.ArrayU32

Indices returns the indices array for this geometry.

func (*Geometry) Init 

func (g *Geometry) Init()

Init initializes the geometry.

func (*Geometry) Items 

func (g *Geometry) Items() int

Items returns the number of items in the first VBO. (The number of items should be same for all VBOs) An item is a complete group of attributes in the VBO buffer.

func (*Geometry) OperateOnVertexNormals 

func (g *Geometry) OperateOnVertexNormals(cb func(normal *math32.Vector3) bool)

OperateOnVertexNormals iterates over all the vertex normals and calls the specified callback function with a pointer to each normal. The vertex pointers can be modified inside the callback and the modifications will be applied to the buffer at each iteration. The callback function returns false to continue or true to break.

func (*Geometry) OperateOnVertices 

func (g *Geometry) OperateOnVertices(cb func(vertex *math32.Vector3) bool)

OperateOnVertices iterates over all the vertices and calls the specified callback function with a pointer to each vertex. The vertex pointers can be modified inside the callback and the modifications will be applied to the buffer at each iteration. The callback function returns false to continue or true to break.

func (*Geometry) ProjectOntoAxis 

func (g *Geometry) ProjectOntoAxis(localAxis *math32.Vector3) (float32, float32)

ProjectOntoAxis projects the geometry onto the specified axis, effectively squashing it into a line passing through the local origin. Returns the maximum and the minimum values on that line (i.e. signed distances from the local origin).

func (*Geometry) ReadFaces 

func (g *Geometry) ReadFaces(cb func(vA, vB, vC math32.Vector3) bool)

ReadFaces iterates over all the vertices and calls the specified callback function with face-forming vertex triples. The callback function returns false to continue or true to break.

func (*Geometry) ReadVertexNormals 

func (g *Geometry) ReadVertexNormals(cb func(vertex math32.Vector3) bool)

ReadVertexNormals iterates over all the vertex normals and calls the specified callback function with the value of each normal. The callback function returns false to continue or true to break.

func (*Geometry) ReadVertices 

func (g *Geometry) ReadVertices(cb func(vertex math32.Vector3) bool)

ReadVertices iterates over all the vertices and calls the specified callback function with the value of each vertex. The callback function returns false to continue or true to break.

func (*Geometry) RenderSetup 

func (g *Geometry) RenderSetup(gs *gls.GLS)

RenderSetup is called by the renderer before drawing the geometry.

func (*Geometry) RotationalInertia 

func (g *Geometry) RotationalInertia(mass float32) math32.Matrix3

RotationalInertia returns the rotational inertia tensor, also known as the moment of inertia. This assumes constant density of 1 (kg/m^2). To adjust for a different constant density simply scale the returning matrix by the density.

func (*Geometry) SetAttributeName 

func (g *Geometry) SetAttributeName(atype gls.AttribType, attribName string)

SetAttributeName sets the name of the VBO attribute associated with the provided attribute type.

func (*Geometry) SetIndices 

func (g *Geometry) SetIndices(indices math32.ArrayU32)

SetIndices sets the indices array for this geometry.

func (*Geometry) SetVAO 

func (g *Geometry) SetVAO(handle uint32)

SetVAO sets the Vertex Array Object handle associated with this geometry.

func (*Geometry) VAO 

func (g *Geometry) VAO() uint32

VAO returns the Vertex Array Object handle associated with this geometry.

func (*Geometry) VBO 

func (g *Geometry) VBO(atype gls.AttribType) *gls.VBO

VBO returns a pointer to this geometry's VBO which contain the specified attribute. Returns nil if the VBO is not found.

func (*Geometry) VBOName 

func (g *Geometry) VBOName(name string) *gls.VBO

VBOName returns a pointer to this geometry's VBO which contain the specified attribute. Returns nil if the VBO is not found.

func (*Geometry) VBOs 

func (g *Geometry) VBOs() []*gls.VBO

VBOs returns all of this geometry's VBOs.

func (*Geometry) Volume 

func (g *Geometry) Volume() float32

Volume returns the volume. NOTE: This only works for closed triangle-based meshes.

type Group 

type Group struct {
	Start    int    // Index of first element of the group
	Count    int    // Number of elements in the group
	Matindex int    // Material index for this group
	Matid    string // Material id used when loading external models
}

Group is a geometry group object.

type IGeometry 

type IGeometry interface {
	GetGeometry() *Geometry
	RenderSetup(gs *gls.GLS)
	Dispose()
}

IGeometry is the interface for all geometries.

type MorphGeometry 

type MorphGeometry struct {
	// contains filtered or unexported fields
}

MorphGeometry represents a base geometry and its morph targets.

func NewMorphGeometry 

func NewMorphGeometry(baseGeometry *Geometry) *MorphGeometry

NewMorphGeometry creates and returns a pointer to a new MorphGeometry.

func (*MorphGeometry) ActiveMorphTargets 

func (mg *MorphGeometry) ActiveMorphTargets() ([]*Geometry, []float32)

ActiveMorphTargets sorts the morph targets by weight and returns the top n morph targets with largest weight.

func (*MorphGeometry) AddMorphTargetDeltas 

func (mg *MorphGeometry) AddMorphTargetDeltas(morphTargetDeltas ...*Geometry)

AddMorphTargetDeltas add multiple morph target deltas to the morph geometry.

func (*MorphGeometry) AddMorphTargets 

func (mg *MorphGeometry) AddMorphTargets(morphTargets ...*Geometry)

AddMorphTargets add multiple morph targets to the morph geometry. Morph target deltas are calculated internally and the morph target geometries are altered to hold the deltas instead.

func (*MorphGeometry) ComputeMorphed 

func (mg *MorphGeometry) ComputeMorphed(weights []float32) *Geometry

ComputeMorphed computes a morphed geometry from the provided morph target weights. Note that morphing is usually computed by the GPU in shaders. This CPU implementation allows users to obtain an instance of a morphed geometry if so desired (loosing morphing ability).

func (*MorphGeometry) Dispose 

func (mg *MorphGeometry) Dispose()

Dispose releases, if possible, OpenGL resources, C memory and VBOs associated with the base geometry and morph targets.

func (*MorphGeometry) GetGeometry 

func (mg *MorphGeometry) GetGeometry() *Geometry

GetGeometry satisfies the IGeometry interface.

func (*MorphGeometry) RenderSetup 

func (mg *MorphGeometry) RenderSetup(gs *gls.GLS)

RenderSetup is called by the renderer before drawing the geometry.

func (*MorphGeometry) SetIndices 

func (mg *MorphGeometry) SetIndices(indices math32.ArrayU32)

SetIndices sets the indices array for this geometry.

func (*MorphGeometry) SetWeights 

func (mg *MorphGeometry) SetWeights(weights []float32)

SetWeights sets the morph target weights.

func (*MorphGeometry) UpdateTargetAttributes 

func (mg *MorphGeometry) UpdateTargetAttributes(morphTargets []*Geometry)

UpdateTargetAttributes updates the attribute names of the specified morph targets in order.

func (*MorphGeometry) Weights 

func (mg *MorphGeometry) Weights() []float32

Weights returns the morph target weights.

type Plane 

type Plane struct {
	Geometry
	Width          float32
	Height         float32
	WidthSegments  int
	HeightSegments int
}

Plane represents a plane geometry

func NewPlane 

func NewPlane(width, height float32, widthSegments, heightSegments int) *Plane

NewPlane creates and returns a pointer to a Plane Geometry. The plane is defined by its width, height and the number of width and height segments. The minimum number of segments for the width and/or the height is 1. The plane is generated centered in the XY plane with Z=0.

type Sphere 

type Sphere struct {
	Geometry
	Radius         float64
	WidthSegments  int
	HeightSegments int
	PhiStart       float64
	PhiLength      float64
	ThetaStart     float64
	ThetaLength    float64
}

Sphere represents a sphere geometry

func NewSphere 

func NewSphere(radius float64, widthSegments, heightSegments int, phiStart, phiLength, thetaStart, thetaLength float64) *Sphere

NewSphere returns a pointer to a new Sphere geometry object

type Torus 

type Torus struct {
	Geometry                // embedded geometry
	Radius          float64 // Torus radius
	Tube            float64 // Diameter of the torus tube
	RadialSegments  int     // Number of radial segments
	TubularSegments int     // Number of tubular segments
	Arc             float64 // Central angle
}

Torus represents a torus geometry

func NewTorus 

func NewTorus(radius, tube float64, radialSegments, tubularSegments int, arc float64) *Torus

NewTorus returns a pointer to a new torus geometry

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