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Improved collision detection algorithm
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-441
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12 files changed

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‎README.md

Lines changed: 6 additions & 1 deletion
Original file line numberDiff line numberDiff line change
@@ -12,9 +12,10 @@ The purpose of this application is to learn and share how to draw using OpenGL l
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* Collada format (DAE): https://en.wikipedia.org/wiki/COLLADA
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15-
News (17/12/2017)
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News (21/12/2017)
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=================
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* Improved collision detection algorithm (ray-aabb)
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* Support for collada files with skeletal animations :)
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* Fixed #28: Load texture feature is now available
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@@ -122,6 +123,10 @@ ChangeLog
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(f) fixed, (i) improved, (n) new feature
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- 2.0.3 (21/12/2017)
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- (i) Improved collision detection algorithm (ray-aabb) for selecting objects
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- (i) BoundingBox code cleanup
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- 2.0.2 (17/12/2017)
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- (f) Collada XML parser is now android's XmlPullParser
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- (f) Animation engine frame times improved

‎app/src/main/java/org/andresoviedo/app/model3D/collision/CollisionDetection.java

Lines changed: 146 additions & 0 deletions
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@@ -0,0 +1,146 @@
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package org.andresoviedo.app.model3D.collision;
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import android.opengl.GLU;
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import android.util.Log;
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import org.andresoviedo.app.model3D.entities.BoundingBox;
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import org.andresoviedo.app.model3D.model.Object3DData;
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import org.andresoviedo.app.model3D.view.ModelRenderer;
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import org.andresoviedo.app.util.math.Math3DUtils;
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import java.util.List;
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/**
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* Class that encapsulates all the logic for the collision detection algorithm.
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*
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* @author andresoviedo
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*/
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public class CollisionDetection {
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/**
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* Get the nearest object intersected by the specified window coordinates
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*
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* @param objects the list of objects to test
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* @param mRenderer the model renderer to unproject window coordinates to world coordinates
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* @param windowX the window x coordinate
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* @param windowY the window y coordinate
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* @return the nearest object intersected by the specified coordinates or null
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*/
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public static Object3DData getIntersection(List<Object3DData> objects, ModelRenderer mRenderer, float windowX, float windowY) {
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float[] nearHit = unproject(mRenderer, windowX, windowY, 0);
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float[] farHit = unproject(mRenderer, windowX, windowY, 1);
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return getIntersection(objects, nearHit, farHit);
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}
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/**
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* Get the nearest object intersected by the specified ray or null if no object is intersected
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*
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* @param objects the list of objects to test
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* @param p1 the ray start point
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* @param p2 the ray end point
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* @return the object intersected by the specified ray
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*/
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public static Object3DData getIntersection(List<Object3DData> objects, float[] p1, float[] p2) {
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float[] direction = Math3DUtils.substract(p2, p1);
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Math3DUtils.normalize(direction);
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float min = Float.MAX_VALUE;
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Object3DData ret = null;
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for (Object3DData obj : objects) {
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if (obj.getId().startsWith("Line")) continue;
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BoundingBox box = obj.getBoundingBox();
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float[] intersection = getBoxIntersection(p1, direction, box);
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if (intersection[0] > 0 && intersection[0] < intersection[1] && intersection[0] < min) {
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min = intersection[0];
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ret = obj;
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}
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}
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if (ret != null) {
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Log.i("CollisionDetection", "Collision detected '" + ret.getId() + "' distance: " + min);
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}
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return ret;
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}
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/**
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* Get the entry and exit point of the ray intersecting the nearest object or null if no object is intersected
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*
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* @param objects list of objects to test
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* @param p1 ray start point
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* @param p2 ray end point
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* @return the entry and exit point of the ray intersecting the nearest object
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*/
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public static float[] getIntersectionPoint(List<Object3DData> objects, float[] p1, float[] p2) {
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float[] direction = Math3DUtils.substract(p2, p1);
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Math3DUtils.normalize(direction);
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float min = Float.MAX_VALUE;
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float[] intersection2 = null;
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Object3DData ret = null;
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for (Object3DData obj : objects) {
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if (obj.getId().startsWith("Line")) continue;
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BoundingBox box = obj.getBoundingBox();
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float[] intersection = getBoxIntersection(p1, direction, box);
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if (intersection[0] > 0 && intersection[0] < intersection[1] && intersection[0] < min) {
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min = intersection[0];
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ret = obj;
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intersection2 = intersection;
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}
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}
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if (ret != null) {
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Log.i("CollisionDetection", "Collision detected '" + ret.getId() + "' distance: " + min);
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return new float[]{p1[0] + direction[0] * min, p1[1] + direction[1] * min, p1[2] + direction[2] * min};
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}
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return null;
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}
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/**
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* Return true if the specified ray intersects the bounding box
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*
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* @param origin origin of the ray
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* @param dir direction of the ray
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* @param b bounding box
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* @return true if the specified ray intersects the bounding box, false otherwise
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*/
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public static boolean isBoxIntersection(float[] origin, float[] dir, BoundingBox b) {
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float[] intersection = getBoxIntersection(origin, dir, b);
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return intersection[0] > 0 && intersection[0] < intersection[1];
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}
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/**
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* Get the intersection points of the near and far plane for the specified ray and bounding box
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*
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* @param origin the ray origin
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* @param dir the ray direction
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* @param b the bounding box
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* @return the intersection points of the near and far plane
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*/
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public static float[] getBoxIntersection(float[] origin, float[] dir, BoundingBox b) {
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float[] tMin = Math3DUtils.divide(Math3DUtils.substract(b.getCurrentMin(), origin), dir);
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float[] tMax = Math3DUtils.divide(Math3DUtils.substract(b.getCurrentMax(), origin), dir);
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float[] t1 = Math3DUtils.min(tMin, tMax);
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float[] t2 = Math3DUtils.max(tMin, tMax);
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float tNear = Math.max(Math.max(t1[0], t1[1]), t1[2]);
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float tFar = Math.min(Math.min(t2[0], t2[1]), t2[2]);
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return new float[]{tNear, tFar};
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}
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/**
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* Get the corresponding near and far vertex for the specified window coordinates
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*
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* @param mRenderer
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* @param rx
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* @param ry
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* @param rz
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* @return the corresponding near and far vertex for the specified window coordinates
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*/
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public static float[] unproject(ModelRenderer mRenderer, float rx, float ry, float rz) {
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float[] xyzw = {0, 0, 0, 0};
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ry = (float) mRenderer.getHeight() - ry;
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int[] viewport = {0, 0, mRenderer.getWidth(), mRenderer.getHeight()};
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GLU.gluUnProject(rx, ry, rz, mRenderer.getModelViewMatrix(), 0, mRenderer.getModelProjectionMatrix(), 0,
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viewport, 0, xyzw, 0);
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xyzw[0] /= xyzw[3];
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xyzw[1] /= xyzw[3];
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xyzw[2] /= xyzw[3];
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xyzw[3] = 1;
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return xyzw;
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}
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}

‎app/src/main/java/org/andresoviedo/app/model3D/controller/TouchController.java

Lines changed: 8 additions & 59 deletions
Original file line numberDiff line numberDiff line change
@@ -1,10 +1,11 @@
11
package org.andresoviedo.app.model3D.controller;
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3+
import org.andresoviedo.app.model3D.collision.CollisionDetection;
4+
import org.andresoviedo.app.model3D.model.Object3DBuilder;
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import org.andresoviedo.app.model3D.model.Object3DData;
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import org.andresoviedo.app.model3D.services.SceneLoader;
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import org.andresoviedo.app.model3D.view.ModelRenderer;
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import org.andresoviedo.app.model3D.view.ModelSurfaceView;
7-
import org.andresoviedo.app.util.math.Math3DUtils;
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import android.graphics.PointF;
1011
import android.opengl.GLU;
@@ -16,6 +17,8 @@
1617
import android.view.View;
1718
import android.widget.ImageView;
1819

20+
import java.util.Arrays;
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1922
public class TouchController {
2023

2124
private static final String TAG = TouchController.class.getName();
@@ -181,11 +184,10 @@ public synchronized boolean onTouchEvent(MotionEvent motionEvent) {
181184
}
182185

183186
if (pointerCount == 1 && simpleTouch) {
184-
// calculate the world coordinates where the user is clicking (near plane and far plane)
185-
float[] hit1 = unproject(x1, y1, 0);
186-
float[] hit2 = unproject(x1, y1, 1);
187-
// check if the ray intersect any of our objects and select the nearer
188-
selectObjectImpl(hit1, hit2);
187+
SceneLoader scene = view.getModelActivity().getScene();
188+
if (scene != null) {
189+
scene.processTouch(x1,y1);
190+
}
189191
}
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@@ -300,59 +302,6 @@ public synchronized boolean onTouchEvent(MotionEvent motionEvent) {
300302
return true;
301303

302304
}
303-
304-
/**
305-
* Get the nearest object intersecting the specified ray and selects it
306-
*
307-
* @param nearPoint
308-
* the near point in world coordinates
309-
* @param farPoint
310-
* the far point in world coordinates
311-
*/
312-
private void selectObjectImpl(float[] nearPoint, float[] farPoint) {
313-
SceneLoader scene = view.getModelActivity().getScene();
314-
if (scene == null) {
315-
return;
316-
}
317-
Object3DData objectToSelect = null;
318-
float objectToSelectDistance = Integer.MAX_VALUE;
319-
for (Object3DData obj : scene.getObjects()) {
320-
Log.i(TAG, "Testing object " + obj.getId());
321-
float distance = Math3DUtils.calculateDistanceOfIntersection(nearPoint, farPoint, obj.getBoundingBox().getCenter(), 1f);
322-
if (distance != -1) {
323-
Log.i(TAG, "Hit object " + obj.getId() + " at distance " + distance);
324-
if (distance < objectToSelectDistance) {
325-
objectToSelectDistance = distance;
326-
objectToSelect = obj;
327-
}
328-
}
329-
}
330-
if (objectToSelect != null) {
331-
Log.i(TAG, "Selected object " + objectToSelect.getId() + " at distance " + objectToSelectDistance);
332-
if (scene.getSelectedObject() == objectToSelect) {
333-
scene.setSelectedObject(null);
334-
} else {
335-
scene.setSelectedObject(objectToSelect);
336-
}
337-
}
338-
}
339-
340-
public float[] unproject(float rx, float ry, float rz) {
341-
float[] xyzw = { 0, 0, 0, 0 };
342-
343-
ry = (float) mRenderer.getHeight() - ry;
344-
345-
int[] viewport = { 0, 0, mRenderer.getWidth(), mRenderer.getHeight() };
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347-
GLU.gluUnProject(rx, ry, rz, mRenderer.getModelViewMatrix(), 0, mRenderer.getModelProjectionMatrix(), 0,
348-
viewport, 0, xyzw, 0);
349-
350-
xyzw[0] /= xyzw[3];
351-
xyzw[1] /= xyzw[3];
352-
xyzw[2] /= xyzw[3];
353-
xyzw[3] = 1;
354-
return xyzw;
355-
}
356305
}
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358307
class TouchScreen {

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