geom

Documentation

Overview

Package geom contains geometry related functionality

Copyright 2015 Markus Dittrich Licensed under BSD license, see LICENSE file for details

Package geom contains geometry related functionality

Copyright 2015 Markus Dittrich Licensed under BSD license, see LICENSE file for details

Index

• Constants
• func Intersect(start, disp vec.Vec3, m *MeshElem) (vec.Vec3, int)
• type Mesh
  • func CreateRect(llc, urc vec.Vec3) Mesh
• type MeshElem
  • func NewMeshElem(v1, v2, v3 vec.Vec3) *MeshElem

Constants

const (
	GEOM_EPSILON   = 1e-12
	GEOM_EPSILON_2 = 1e-24
)

these epsilon is used for geometrical comparison. Anything smaller than that is assumed to be identical. FIXME: This is currently chosen arbitrarily and requires more thinking.

Functions

func Intersect

func Intersect(start, disp vec.Vec3, m *MeshElem) (vec.Vec3, int)

Intersect tests for ray triangle intersections. Possible return values are

0: triangle and ray segment intersect, in this case hitPoint contains the
   location of the intersection point
1: triangle and ray intersect but ray segment does not reach the triangle
2: triangle and ray do not intersect
3: ray and triangle are co-planar
4: triangle is degenerate

NOTE: This function was adapted from Dan Sunday <http://geomalgorithms.com/a06-_intersect-2.html#intersect3D_RayTriangle()>

Types

type Mesh

type Mesh []MeshElem

Mesh is a collection of MeshElements

func CreateRect

func CreateRect(llc, urc vec.Vec3) Mesh

CreateRect is a helper function creating a rectangular Mesh consisting of 12 individual MeshElem. The rectangle dimensions are specified by providing the coordinates of the lower left and upper right vertex

type MeshElem

type MeshElem struct {
	A, B, C vec.Vec3 // triangle vertices
	U, V    vec.Vec3 // u, v coordinates of mesh element
	N, NN   vec.Vec3 // normal and normalized normal vectors
}

MeshElem describes a single triangular mesh element which may be part of a larger Mesh object.

func NewMeshElem

func NewMeshElem(v1, v2, v3 vec.Vec3) *MeshElem

NewMeshElem creates a new MeshElem and also properly computes the additional data members. NOTE: NewMeshElem assumes that v1, v2, v3 are not colinear, otherwise the function will panic