= terrain_collision :revnumber: 2.1 :revdate: 2020/07/24 :keywords: terrain, collision == Terrain Collision This tutorial expands the HelloTerrain tutorial and makes the terrain solid. You combine what you learned in xref:tutorials:beginner/hello_terrain.adoc[Hello Terrain] and xref:tutorials:beginner/hello_collision.adoc[Hello Collision] and add a CollisionShape to the terrain. The terrain's CollisionShape lets the first-person player (who is also a CollisionShape) collide with the terrain, i.e. walk on it and stand on it. == Sample Code [source,java] ---- package jme3test.helloworld; import com.jme3.app.SimpleApplication; import com.jme3.bullet.BulletAppState; import com.jme3.bullet.collision.shapes.CapsuleCollisionShape; import com.jme3.bullet.collision.shapes.CollisionShape; import com.jme3.bullet.control.CharacterControl; import com.jme3.bullet.control.RigidBodyControl; import com.jme3.bullet.util.CollisionShapeFactory; import com.jme3.input.KeyInput; import com.jme3.input.controls.ActionListener; import com.jme3.input.controls.KeyTrigger; import com.jme3.material.Material; import com.jme3.math.Vector3f; import com.jme3.renderer.Camera; import com.jme3.scene.Node; import com.jme3.terrain.geomipmap.TerrainLodControl; import com.jme3.terrain.heightmap.AbstractHeightMap; import com.jme3.terrain.geomipmap.TerrainQuad; import com.jme3.terrain.heightmap.ImageBasedHeightMap; import com.jme3.texture.Texture; import com.jme3.texture.Texture.WrapMode; import java.util.ArrayList; import java.util.List; import jme3tools.converters.ImageToAwt; /** * This demo shows a terrain with collision detection, * that you can walk around in with a first-person perspective. * This code combines HelloCollision and HelloTerrain. */ public class HelloTerrainCollision extends SimpleApplication implements ActionListener { private BulletAppState bulletAppState; private RigidBodyControl landscape; private CharacterControl player; private Vector3f walkDirection = new Vector3f(); private boolean left = false, right = false, up = false, down = false; private TerrainQuad terrain; private Material mat_terrain; public static void main(String[] args) { HelloTerrainCollision app = new HelloTerrainCollision(); app.start(); } @Override public void simpleInitApp() { /** Set up Physics */ bulletAppState = new BulletAppState(); stateManager.attach(bulletAppState); //Uncomment for debugging.   //bulletAppState.setDebugEnabled(true); flyCam.setMoveSpeed(100); setUpKeys(); /** 1. Create terrain material and load four textures into it. */ mat_terrain = new Material(assetManager, "Common/MatDefs/Terrain/Terrain.j3md"); /** 1.1) Add ALPHA map (for red-blue-green coded splat textures) */ mat_terrain.setTexture("Alpha", assetManager.loadTexture( "Textures/Terrain/splat/alphamap.png")); /** 1.2) Add GRASS texture into the red layer (Tex1). */ Texture grass = assetManager.loadTexture( "Textures/Terrain/splat/grass.jpg"); grass.setWrap(WrapMode.Repeat); mat_terrain.setTexture("Tex1", grass); mat_terrain.setFloat("Tex1Scale", 64f); /** 1.3) Add DIRT texture into the green layer (Tex2) */ Texture dirt = assetManager.loadTexture( "Textures/Terrain/splat/dirt.jpg"); dirt.setWrap(WrapMode.Repeat); mat_terrain.setTexture("Tex2", dirt); mat_terrain.setFloat("Tex2Scale", 32f); /** 1.4) Add ROAD texture into the blue layer (Tex3) */ Texture rock = assetManager.loadTexture( "Textures/Terrain/splat/road.jpg"); rock.setWrap(WrapMode.Repeat); mat_terrain.setTexture("Tex3", rock); mat_terrain.setFloat("Tex3Scale", 128f); /** 2. Create the height map */ AbstractHeightMap heightmap = null; Texture heightMapImage = assetManager.loadTexture( "Textures/Terrain/splat/mountains512.png"); heightmap = new ImageBasedHeightMap(heightMapImage.getImage()); heightmap.load(); /** 3. We have prepared material and heightmap. * Now we create the actual terrain: * 3.1) Create a TerrainQuad and name it "my terrain". * 3.2) A good value for terrain tiles is 64x64 -- so we supply 64+1=65. * 3.3) We prepared a heightmap of size 512x512 -- so we supply 512+1=513. * 3.4) As LOD step scale we supply Vector3f(1,1,1). * 3.5) We supply the prepared heightmap itself. */ terrain = new TerrainQuad("my terrain", 65, 513, heightmap.getHeightMap()); /** 4. We give the terrain its material, position & scale it, and attach it. */ terrain.setMaterial(mat_terrain); terrain.setLocalTranslation(0, -100, 0); terrain.setLocalScale(2f, 1f, 2f); rootNode.attachChild(terrain); /** 5. The LOD (level of detail) depends on were the camera is: */ List cameras = new ArrayList(); cameras.add(getCamera()); TerrainLodControl control = new TerrainLodControl(terrain, cameras); terrain.addControl(control); /** 6. Add physics: * We set up collision detection for the scene by creating a static * RigidBodyControl with mass zero. */ terrain.addControl(new RigidBodyControl(0)); /** * We set up collision detection for the player by creating * a capsule collision shape and a CharacterControl. * The CharacterControl offers extra settings for * size, stepheight, jumping, falling, and gravity. * We also put the player in its starting position. */ CapsuleCollisionShape capsuleShape = new CapsuleCollisionShape(1.5f, 6f, 1); player = new CharacterControl(capsuleShape, 0.05f); player.setJumpSpeed(20); player.setFallSpeed(30); player.setPhysicsLocation(new Vector3f(-10, 10, 10)); // We attach the scene and the player to the rootnode and the physics space, // to make them appear in the game world. bulletAppState.getPhysicsSpace().add(terrain); bulletAppState.getPhysicsSpace().add(player); // You can change the gravity of individual physics objects after they are // added to the PhysicsSpace. player.setGravity(new Vector3f(0,-30f,0)); } /** We over-write some navigational key mappings here, so we can * add physics-controlled walking and jumping: */ private void setUpKeys() { inputManager.addMapping("Left", new KeyTrigger(KeyInput.KEY_A)); inputManager.addMapping("Right", new KeyTrigger(KeyInput.KEY_D)); inputManager.addMapping("Up", new KeyTrigger(KeyInput.KEY_W)); inputManager.addMapping("Down", new KeyTrigger(KeyInput.KEY_S)); inputManager.addMapping("Jump", new KeyTrigger(KeyInput.KEY_SPACE)); inputManager.addListener(this, "Left"); inputManager.addListener(this, "Right"); inputManager.addListener(this, "Up"); inputManager.addListener(this, "Down"); inputManager.addListener(this, "Jump"); } /** These are our custom actions triggered by key presses. * We do not walk yet, we just keep track of the direction the user pressed. */ public void onAction(String binding, boolean value, float tpf) { if (binding.equals("Left")) { if (value) { left = true; } else { left = false; } } else if (binding.equals("Right")) { if (value) { right = true; } else { right = false; } } else if (binding.equals("Up")) { if (value) { up = true; } else { up = false; } } else if (binding.equals("Down")) { if (value) { down = true; } else { down = false; } } else if (binding.equals("Jump")) { player.jump(new Vector3f(0,20f,0)); } } /** * This is the main event loop--walking happens here. * We check in which direction the player is walking by interpreting * the camera direction forward (camDir) and to the side (camLeft). * The setWalkDirection() command is what lets a physics-controlled player walk. * We also make sure here that the camera moves with player. */ @Override public void simpleUpdate(float tpf) { Vector3f camDir = cam.getDirection().clone().multLocal(0.6f); Vector3f camLeft = cam.getLeft().clone().multLocal(0.4f); walkDirection.set(0, 0, 0); if (left) { walkDirection.addLocal(camLeft); } if (right) { walkDirection.addLocal(camLeft.negate()); } if (up) { walkDirection.addLocal(camDir); } if (down) { walkDirection.addLocal(camDir.negate()); } player.setWalkDirection(walkDirection); cam.setLocation(player.getPhysicsLocation()); } } ---- To try this code, create a `menu:New Project[JME3 > BasicGame]` using the default settings. Paste the sample code over the pregenerated Main.java class. Change the package to '`mygame`' if necessary. Open the `menu:File[Project Properties > Libraries]` and add the `jme3-test-data` library to make certain you have all the files. Compile and run the code. You should see a terrain. You can use the WASD keys and the mouse to run up and down the hills. == Understanding the Code === The Terrain Code Read xref:tutorials:beginner/hello_terrain.adoc[Hello Terrain] for details of the following parts that we reuse: . The `AbstractHeightMap` is an efficient way to describe the shape of the terrain. . The `Terrain.j3md`-based Material and its texture layers let you colorize rocky mountain, grassy valleys, and a paved path criss-crossing over the landscape. . The TerrainQuad is the finished `terrain` Spatial that you attach to the rootNode. === The Collision Detection Code Read xref:tutorials:beginner/hello_collision.adoc[Hello Collision] for details of the following parts that we reuse: . The `BulletAppState` lines activate physics. . The `ActionListener` (`onAction()`) lets you reconfigure the input handling for the first-person player, so it takes collision detection into account. . The custom `setUpKeys()` method loads your reconfigured input handlers. They now don't just walk blindly, but calculate the `walkDirection` vector that we need for collision detection. . `simpleUpdate()` uses the `walkDirection` vector and makes the character walk, while taking obstacles and solid walls/floor into account. [source,java] ---- player.setWalkDirection(walkDirection); ---- . The RigidBodyControl `landscape` is the CollisionShape of the terrain. . The physical first-person player is a CapsuleCollisionShape with a CharacterControl. === Combining the Two Here are the changed parts to combine the two: . You create a static (zero-mass) RigidBodyControl. . Add the control to the `terrain` to make it physical. [source,java] ---- /** 6. Add physics: */ terrain.addControl(new RigidBodyControl(0)); ---- You attach the `terrain` and the first-person `player` to the rootNode, and to the physics space, to make them appear in the game world. [source,java] ---- bulletAppState.getPhysicsSpace().add(terrain); bulletAppState.getPhysicsSpace().add(player); ---- == Conclusion You see that you can combine snippets of sample code (such as HelloTerrain and HelloCollision), and create a new application from it that combines two features into something new. You should spawn high up in the area and fall down to the map, giving you a few seconds to survey the area. Then walk around and see how you like the lay of the land. ''' See also: * xref:tutorials:beginner/hello_terrain.adoc[Hello Terrain], * xref:terrain/terrain.adoc[Terrain]