Implementation of parallel optical projection in Java3D

Implementation of parallel optical projection in Java3D

Jackjoesh Column

Theoretical Basis:
Assume that the direction of a light is (-1,-1,-1) and is projected to the xz plane.

One is a linear equation and the other is a plane equation.
Furthermore, the plane equation is quite special. After the origin, the normal vector is 0 1 0.
It is simplified. Assume that V is the direction of a straight line.

X-vertex. x y-vertex. y z-vertex.z
---------------- = --------------- = -------------- Linear Equation
V. X v. Y v. Z

Plane equation Y = 0

Bring in.
X = vertex. x + v. X/V. y * (-vertex. Y)
Z = vertex. Z + v. X/V. z * (-vertex. Z)

Source program:
Import java. Applet. Applet;
Import java. AWT. borderlayout;
Import java. AWT. graphicsconfiguration;
Import java. AWT. label;
Import com. Sun. j3d. utils. Applet. Mainframe;
Import com. Sun. j3d. utils. Universe .*;
Import com. Sun. j3d. utils. Geometry .*;
Import javax. Media. j3d .*;
Import javax. vecmath .*;
Public class simpleshadow extends applet {
// Triangular plane
Public class triplane extends shape3d {
Triplane (point3f A, point3f B, point3f c ){
This. setgeometry (this. creategeometry3 (a, B, c ));
This. setappearance (this. createappearance ());
}
// Create a Triangle Plane

Geometry creategeometry3 (point3f A, point3f B, point3f c ){
Trianglearray plane = new trianglearray (3, geometryarray. Coordinates | geometryarray. normals );
// Set the coordinates of the three vertices in the plane
Plane. setcoordinate (0, );
Plane. setcoordinate (1, B );
Plane. setcoordinate (2, c );

// Calculate the flat Vector
Vector3f A = new vector3f (A. x-B.x, A. y-B.y, A. z-B.z );
Vector3f B = new vector3f (C. x-B.x, C. y-B.y, C. z-B.z );
Vector3f n = new vector3f ();
N. Cross (B, );
// Method vector unitization
N. normalize ();
// Set the normal vector of three vertices in the plane
Plane. setnormal (0, N );
Plane. setnormal (1, N );
Plane. setnormal (2, N );
Return plane;
}

// Create a material appearance that is not empty

Appearance createappearance (){
Appearance appear = new appearance ();
Material material = new material ();
Appear. setmaterial (material );
Return appear;
}

}
 
 
// Four-sided plane
Public class quadplane extends shape3d {

Quadplane (point3f A, point3f B, point3f C, point3f d ){
This. setgeometry (this. creategeometry4 (A, B, C, D ));
This. setappearance (this. createappearance ());
}

// Create a four-sided plane
Geometry creategeometry4 (point3f A, point3f B, point3f C, point3f d ){
Quadarray plane = new quadarray (4, geometryarray. Coordinates | geometryarray. normals );
// Set the coordinates of the three vertices in the plane
Plane. setcoordinate (0, );
Plane. setcoordinate (1, B );
Plane. setcoordinate (2, c );
Plane. setcoordinate (3, D );
// Calculate the flat Vector
Vector3f A = new vector3f (A. x-B.x, A. y-B.y, A. z-B.z );
Vector3f B = new vector3f (C. x-B.x, C. y-B.y, C. z-B.z );
Vector3f n = new vector3f ();
N. Cross (B, );
// Method vector unitization
N. normalize ();
// Set the normal vector of four vertices in the plane
Plane. setnormal (0, N );
Plane. setnormal (1, N );
Plane. setnormal (2, N );
Plane. setnormal (3, N );
Return plane;
}

// Create a material appearance that is not empty

Appearance createappearance (){
Appearance appear = new appearance ();
Material material = new material ();
Appear. setmaterial (material );
Return appear;
}
}
 
 
// Shadow class
Public class shadow3d extends shape3d {
Shadow3d (geometryarray Geom, vector3f ction, color3f Col, float height ){
Int vcount = Geom. getvertexcount ();
Trianglearray poly = new trianglearray (vcount, geometryarray. Coordinates | geometryarray. color_3 );
Int V;
Point3f vertex = new point3f ();
Point3f shadow = new point3f ();

For (V = 0; v <vcount; V ++ ){
// Calculate the projection coordinate of the Meeting Vertex on the projection plane
Geom. getcoordinate (v, vertex );
System. Out. println (vertex. Y-height );
Shadow. Set (vertex. X-(vertex. Y-height), height + 0.0001f, vertex. Z-(vertex. Y-height ));
Poly. setcoordinate (v, shadow );
Poly. setcolor (v, col );

}
This. setgeometry (poly );

}
}
 
 
Public simpleshadow (){
This. setlayout (New borderlayout ());
// Graphicsconfiguration Config = simpleuniverse. getpreferredconfiguration ();
Canvas3d c = new canvas3d (null );
This. Add ("center", C );
// Create a branch node
Branchgroup scene = new branchgroup ();
// Create a triangle visible plane
Shape3d plane = new triplane (New point3f (0.0f, 0.6f,-0.2f), new point3f (-0.3f,-0.3f, 0.2f), new point3f (0.6f,-0.3f, 0.2f ));
// Add to the root branch node
Scene. addchild (plane );
// Create a quadrilateral projection plane
Shape3d floor = new quadplane (New point3f (-1.0f,-0.5f,-1.0f), new point3f (-1.0f,-0.5f, 1.0f), new point3f (1.0f,-0.5f, 1.0f), new point3f (1.0f,-0.5f,-1.0f ));
// Add to the root branch node
Scene. addchild (floor );
// Add to ambient light
Ambientlight lighta = new ambientlight ();
Lighta. setinfluencingbounds (New boundingsphere ());
Scene. addchild (lighta );
// Add parallel light
Directionallight lightd1 = new directionallight ();
Lightd1.setinfluencingbounds (New boundingsphere ());
Vector3f direction = new vector3f (-1.0f,-1.0f,-1.0f );
// Vector unit Orientation
Direction. normalize ();
Lightd1.setdirection (Direction );
Scene. addchild (lightd1 );
// Create a shadow object
Shape3d shadow = new shadow3d (geometryarray) plane. getgeometry (), direction, new color3f (0.2f, 0.2f, 0.2f),-0.5f );
Scene. addchild (Shadow );
Simpleuniverse u = new simpleuniverse (C );
U. getviewingplatform (). setnominalviewingtransform ();
U. addbranchgraph (scene );
}
 
Public static void main (string argv []) {
New mainframe (New simpleshadow (), 256,256 );
}

}

Details:

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