134 lines
3.8 KiB
Java
134 lines
3.8 KiB
Java
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import algebra.*;
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/**
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* author: cdehais
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*/
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public class Transformation {
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Matrix worldToCamera;
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Matrix projection;
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Matrix calibration;
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public Transformation() {
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try {
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worldToCamera = new Matrix("W2C", 4, 4);
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projection = new Matrix("P", 3, 4);
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calibration = Matrix.createIdentity(3);
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calibration.setName("K");
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} catch (InstantiationException e) {
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/* should not be reached */
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}
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}
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public void setLookAt(Vector3 cam, Vector3 lookAt, Vector3 up) {
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try {
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// compute rotation
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Vector3 e3c = new Vector3(lookAt);
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e3c.subtract(cam);
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e3c.normalize();
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Vector3 e1c = up.cross(e3c);
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e1c.normalize();
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Vector3 e2c = e3c.cross(e1c);
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// insertion de la matrice de rotation (transposée), dans worldToCamera
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worldToCamera.set(0, 0, e1c.get(0));
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worldToCamera.set(0, 1, e1c.get(1));
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worldToCamera.set(0, 2, e1c.get(2));
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worldToCamera.set(1, 0, e2c.get(0));
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worldToCamera.set(1, 1, e2c.get(1));
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worldToCamera.set(1, 2, e2c.get(2));
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worldToCamera.set(2, 0, e3c.get(0));
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worldToCamera.set(2, 1, e3c.get(1));
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worldToCamera.set(2, 2, e3c.get(2));
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// le vecteur de zeros sous la rotation, dans worldToCamera
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worldToCamera.set(3, 0, 0);
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worldToCamera.set(3, 1, 0);
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worldToCamera.set(3, 2, 0);
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// le 1 en bas à droite, dans worldToCamera
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worldToCamera.set(3, 3, 1);
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// compute translation
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Matrix M = worldToCamera.getSubMatrix(0, 0, 3, 3);
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Vector t = M.multiply(cam);
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// insertion du vecteur translation, dans worldToCamera
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worldToCamera.set(0, 3, -t.get(0));
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worldToCamera.set(1, 3, -t.get(1));
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worldToCamera.set(2, 3, -t.get(2));
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} catch (Exception e) {
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/* unreached */
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}
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System.out.println("Modelview matrix:\n" + worldToCamera);
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}
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public void setProjection() {
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// matrice "identitée" 3x4
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projection.set(0, 0, 1);
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projection.set(1, 1, 1);
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projection.set(2, 2, 1);
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System.out.println("Projection matrix:\n" + projection);
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}
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public void setCalibration(double focal, double width, double height) {
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// focal sur la diagonale, sauf en bas à droite
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calibration.set(0, 0, focal);
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calibration.set(1, 1, focal);
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// translation de w/2 et h/2
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calibration.set(0, 2, width / 2);
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calibration.set(1, 2, height / 2);
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System.out.println("Calibration matrix:\n" + calibration);
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}
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/**
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* Projects the given homogeneous, 4 dimensional point onto the screen.
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* The resulting Vector as its (x,y) coordinates in pixel, and its z coordinate
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* is the depth of the point in the camera coordinate system.
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*/
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public Vector3 projectPoint(Vector p) throws SizeMismatchException, InstantiationException {
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Vector ps = new Vector(3);
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// projection du point dans le plan
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ps = calibration.multiply(projection.multiply(worldToCamera.multiply(p)));
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double depth = ps.get(2);
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// "normalisation" des coordonnées du point
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ps.set(0, ps.get(0) / depth);
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ps.set(1, ps.get(1) / depth);
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// ps.scale(1 / depth);
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return new Vector3(ps);
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}
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/**
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* Transform a vector from world to camera coordinates.
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*/
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public Vector3 transformVector(Vector3 v) throws SizeMismatchException, InstantiationException {
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/* Doing nothing special here because there is no scaling */
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Matrix R = worldToCamera.getSubMatrix(0, 0, 3, 3);
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Vector tv = R.multiply(v);
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return new Vector3(tv);
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}
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}
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