glmodel
Class GL_Triangle

java.lang.Object
  glmodel.GL_Triangle

public class GL_Triangle
extends java.lang.Object

Describes a triangular face. Holds references to three vertices, their normals and texture coodinates. Vertex normals are stored here and not in the Vertex object because a vertex may be shared between two or more faces, and the faces may have very different normals (ie. if the faces are at a 90 degree angle and make a sharp edge). To smooth normals and preserve sharp edges, the Triangle object holds the neighboring triangles for each vert. Based on the angles between this triangle and its neighbors, the smoothing algorithm can decide whether to smooth the normals across the triangles, or to use the face normal to create a hard edge. jun 2006: added makeClone()

Field Summary

int	groupID
int	ID
GL_Vector	n
java.util.ArrayList	neighborsP1
java.util.ArrayList	neighborsP2
java.util.ArrayList	neighborsP3
GL_Vector	norm1
GL_Vector	norm2
GL_Vector	norm3
GL_Vertex	p1
GL_Vertex	p2
GL_Vertex	p3
GL_Vector	uvw1
GL_Vector	uvw2
GL_Vector	uvw3
float	Zdepth

Constructor Summary

GL_Triangle(GL_Vertex a, GL_Vertex b, GL_Vertex c)

Method Summary

void	calcZdepth() Calculate average screen Z depth of this triangle.
GL_Vector	getCenter()
GL_Vector	getWeightedNormal()
GL_Triangle	makeClone()
static boolean	onSameSurface(GL_Triangle t1, GL_Triangle t2, float cos_angle) Return true if two triangles should be smoothed as one surface.
void	recalcFaceNormal() Calculate the face normal for this triangle
GL_Vector	recalcVertexNormal(java.util.ArrayList neighbors) Recalculate the vertex normal, by averagin the normals of the neighboring triangles.
void	resetNeighbors()

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Field Detail

p1

public GL_Vertex p1

p2

public GL_Vertex p2

p3

public GL_Vertex p3

norm1

public GL_Vector norm1

norm2

public GL_Vector norm2

norm3

public GL_Vector norm3

uvw1

public GL_Vector uvw1

uvw2

public GL_Vector uvw2

uvw3

public GL_Vector uvw3

neighborsP1

public java.util.ArrayList neighborsP1

neighborsP2

public java.util.ArrayList neighborsP2

neighborsP3

public java.util.ArrayList neighborsP3

n

public GL_Vector n

Zdepth

public float Zdepth

ID

public int ID

groupID

public int groupID

Constructor Detail

GL_Triangle

public GL_Triangle(GL_Vertex a,
                   GL_Vertex b,
                   GL_Vertex c)

Method Detail

recalcFaceNormal

public void recalcFaceNormal()

Calculate the face normal for this triangle

recalcVertexNormal

public GL_Vector recalcVertexNormal(java.util.ArrayList neighbors)

Recalculate the vertex normal, by averagin the normals of the neighboring triangles. The neighbor list holds only triangles that we want to average with this vertex.

Parameters:

neighbors - neighboring triangles for this vert

Returns:

vertex normal

See Also:

GL_Object.registerNeighbors()

getWeightedNormal

public GL_Vector getWeightedNormal()

getCenter

public GL_Vector getCenter()

resetNeighbors

public void resetNeighbors()

calcZdepth

public void calcZdepth()

Calculate average screen Z depth of this triangle. This function requires that the vertex screen positions have been set (vertex.posS).

See Also:

GL_Mesh.project()

onSameSurface

public static boolean onSameSurface(GL_Triangle t1,
                                    GL_Triangle t2,
                                    float cos_angle)

Return true if two triangles should be smoothed as one surface. cos_angle is the minumum angle for smoothing. If the angle between the faces is > cos_angle, then the faces are considered to be a continuous surface. Ie. 90 degrees is a sharp corner, 180 degrees is a flat surface.

makeClone

public GL_Triangle makeClone()