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Added proper documentation for camera.getWorldCoordinates

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Added a convenience method to compute z in projection space from z in view space

git-svn-id: https://jmonkeyengine.googlecode.com/svn/trunk@9934 75d07b2b-3a1a-0410-a2c5-0572b91ccdca
This commit is contained in:
rem..om 2012-11-01 22:49:34 +00:00
parent f8f4a9e33e
commit 76dcabae66
1 changed files with 34 additions and 8 deletions
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36
engine/src/core/com/jme3/renderer/Camera.java
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@ -1296,17 +1296,43 @@ public class Camera implements Savable, Cloneable {
}
/**
* @see Camera#getWorldCoordinates
* Computes the z value in projection space from the z value in view space
* Note that the returned value is going non linearly from 0 to 1.
* for more explanations on non linear z buffer see
* http://www.sjbaker.org/steve/omniv/love_your_z_buffer.html
* @param viewZPos the z value in view space.
* @return the z value in projection space.
*/
public Vector3f getWorldCoordinates(Vector2f screenPos, float zPos) {
return getWorldCoordinates(screenPos, zPos, null);
public float getViewToProjectionZ(float viewZPos) {
float far = getFrustumFar();
float near = getFrustumNear();
float a = far / (far - near);
float b = far * near / (near - far);
return a + b / viewZPos;
}
/**
* Computes a position in World space given a screen position in screen space (0,0 to width, height)
* and a z position in projection space ( 0 to 1 non linear).
* This former value is also known as the Z buffer value or non linear depth buffer.
* for more explanations on non linear z buffer see
* http://www.sjbaker.org/steve/omniv/love_your_z_buffer.html
*
* To compute the projection space z from the view space z (distance from cam to object) @see Camera#getViewToProjectionZ
*
* @param screenPos 2d coordinate in screen space
* @param projectionZPos non linear z value in projection space
* @return the position in world space.
*/
public Vector3f getWorldCoordinates(Vector2f screenPos, float projectionZPos) {
return getWorldCoordinates(screenPos, projectionZPos, null);
}
/**
* @see Camera#getWorldCoordinates
*/
public Vector3f getWorldCoordinates(Vector2f screenPosition,
float zPos, Vector3f store) {
float projectionZPos, Vector3f store) {
if (store == null) {
store = new Vector3f();
}
@ -1317,7 +1343,7 @@ public class Camera implements Savable, Cloneable {
store.set(
(screenPosition.x / getWidth() - viewPortLeft) / (viewPortRight - viewPortLeft) * 2 - 1,
(screenPosition.y / getHeight() - viewPortBottom) / (viewPortTop - viewPortBottom) * 2 - 1,
zPos * 2 - 1);
projectionZPos * 2 - 1);
float w = inverseMat.multProj(store, store);
store.multLocal(1f / w);