apps: add HelloWalk

apps/src/main/java/com/github/stephengold/vsport/tutorial/HelloWalk.java

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+/*
+ Copyright (c) 2020-2023, Stephen Gold
+ All rights reserved.
+
+ Redistribution and use in source and binary forms, with or without
+ modification, are permitted provided that the following conditions are met:
+
+ 1. Redistributions of source code must retain the above copyright notice, this
+    list of conditions and the following disclaimer.
+
+ 2. Redistributions in binary form must reproduce the above copyright notice,
+    this list of conditions and the following disclaimer in the documentation
+    and/or other materials provided with the distribution.
+
+ 3. Neither the name of the copyright holder nor the names of its
+    contributors may be used to endorse or promote products derived from
+    this software without specific prior written permission.
+
+ THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS" AND
+ ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED
+ WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE
+ DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT HOLDER OR CONTRIBUTORS BE LIABLE
+ FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR
+ SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER
+ CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY,
+ OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE
+ OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+package com.github.stephengold.vsport.tutorial;
+
+import com.github.stephengold.vsport.Constants;
+import com.github.stephengold.vsport.Utils;
+import com.github.stephengold.vsport.input.InputProcessor;
+import com.github.stephengold.vsport.input.RotateMode;
+import com.github.stephengold.vsport.physics.BasePhysicsApp;
+import com.jme3.bullet.PhysicsSpace;
+import com.jme3.bullet.PhysicsTickListener;
+import com.jme3.bullet.collision.shapes.CapsuleCollisionShape;
+import com.jme3.bullet.collision.shapes.CollisionShape;
+import com.jme3.bullet.collision.shapes.HeightfieldCollisionShape;
+import com.jme3.bullet.objects.PhysicsBody;
+import com.jme3.bullet.objects.PhysicsCharacter;
+import com.jme3.bullet.objects.PhysicsRigidBody;
+import com.jme3.math.Vector3f;
+import java.awt.image.BufferedImage;
+import org.joml.Vector4f;
+import org.joml.Vector4fc;
+import org.lwjgl.glfw.GLFW;
+
+/**
+ * A simple example of character physics.
+ * <p>
+ * Press the W key to walk. Press the space bar to jump.
+ * <p>
+ * Builds upon HelloCharacter.
+ *
+ * @author Stephen Gold [email protected]
+ */
+public class HelloWalk
+        extends BasePhysicsApp<PhysicsSpace>
+        implements PhysicsTickListener {
+    // *************************************************************************
+    // fields
+
+    /**
+     * true when the spacebar is pressed, otherwise false
+     */
+    private static volatile boolean jumpRequested;
+    /**
+     * true when the W key is pressed, otherwise false
+     */
+    private static volatile boolean walkRequested;
+    /**
+     * character being tested
+     */
+    private static PhysicsCharacter character;
+    // *************************************************************************
+    // new methods exposed
+
+    /**
+     * Main entry point for the HelloWalk application.
+     *
+     * @param arguments array of command-line arguments (not null)
+     */
+    public static void main(String[] arguments) {
+        HelloWalk application = new HelloWalk();
+        application.start();
+    }
+    // *************************************************************************
+    // BasePhysicsApp methods
+
+    /**
+     * Create the PhysicsSpace. Invoked once during initialization.
+     *
+     * @return a new instance
+     */
+    @Override
+    public PhysicsSpace createSpace() {
+        PhysicsSpace result
+                = new PhysicsSpace(PhysicsSpace.BroadphaseType.DBVT);
+
+        // To enable the callbacks, register the application as a tick listener.
+        result.addTickListener(this);
+
+        return result;
+    }
+
+    /**
+     * Initialize the application.
+     */
+    @Override
+    public void initialize() {
+        super.initialize();
+
+        configureCamera();
+        configureInput();
+        configureLighting();
+    }
+
+    /**
+     * Populate the PhysicsSpace. Invoked once during initialization.
+     */
+    @Override
+    public void populateSpace() {
+        // Create a character with a capsule shape and add it to the space.
+        float capsuleRadius = 3f;
+        float capsuleHeight = 4f;
+        CapsuleCollisionShape shape
+                = new CapsuleCollisionShape(capsuleRadius, capsuleHeight);
+        float stepHeight = 0.01f;
+        character = new PhysicsCharacter(shape, stepHeight);
+        character.setGravity(60f);
+        physicsSpace.addCollisionObject(character);
+
+        // Teleport the character to its initial location.
+        character.setPhysicsLocation(new Vector3f(-73.6f, 19.09f, -45.58f));
+
+        // Add a static heightmap to represent the ground.
+        addTerrain();
+    }
+    // *************************************************************************
+    // PhysicsTickListener methods
+
+    /**
+     * Callback from Bullet, invoked just before each simulation step.
+     *
+     * @param space the space that's about to be stepped (not null)
+     * @param timeStep the time per simulation step (in seconds, &ge;0)
+     */
+    @Override
+    public void prePhysicsTick(PhysicsSpace space, float timeStep) {
+        // Clear any motion from the previous simulation step.
+        character.setWalkDirection(Vector3f.ZERO);
+        /*
+         * If the character is touching the ground,
+         * cause it respond to keyboard input.
+         */
+        if (character.onGround()) {
+            if (jumpRequested) {
+                character.jump();
+
+            } else if (walkRequested) {
+                // Walk in the camera's forward direction.
+                Vector3f offset = cam.getDirection();
+                float walkSpeed = 7f;
+                offset.multLocal(walkSpeed * timeStep);
+                character.setWalkDirection(offset);
+            }
+        }
+    }
+
+    /**
+     * Callback from Bullet, invoked just after each simulation step.
+     *
+     * @param space the space that was just stepped (not null)
+     * @param timeStep the time per simulation step (in seconds, &ge;0)
+     */
+    @Override
+    public void physicsTick(PhysicsSpace space, float timeStep) {
+        Vector3f location = character.getPhysicsLocation(null);
+        cam.setLocation(location);
+    }
+    // *************************************************************************
+    // private methods
+
+    /**
+     * Add a heightfield body to the space.
+     */
+    private void addTerrain() {
+        // Generate an array of heights from a PNG image on the classpath.
+        String resourceName = "/Textures/Terrain/splat/mountains512.png";
+        BufferedImage image = Utils.loadResourceAsImage(resourceName);
+
+        float maxHeight = 51f;
+        float[] heightArray = Utils.toHeightArray(image, maxHeight);
+
+        // Construct a static rigid body based on the array of heights.
+        CollisionShape shape = new HeightfieldCollisionShape(heightArray);
+        PhysicsRigidBody body
+                = new PhysicsRigidBody(shape, PhysicsBody.massForStatic);
+
+        physicsSpace.addCollisionObject(body);
+
+        // Visualize the terrain.
+        Vector4fc darkGreen = new Vector4f(0f, 0.3f, 0f, 1f);
+        visualizeShape(body)
+                .setColor(darkGreen)
+                .setSpecularColor(Constants.BLACK);
+    }
+
+    /**
+     * Configure the projection and CIP during startup.
+     */
+    private static void configureCamera() {
+        getCameraInputProcessor().setRotationMode(RotateMode.DragLMB);
+        getProjection().setFovyDegrees(30f);
+
+        // Bring the near plane closer to reduce clipping.
+        getProjection().setZClip(0.1f, 1_000f);
+    }
+
+    /**
+     * Configure keyboard input during startup.
+     */
+    private void configureInput() {
+        getInputManager().add(new InputProcessor() {
+            @Override
+            public void onKeyboard(int keyId, boolean isPressed) {
+                switch (keyId) {
+                    case GLFW.GLFW_KEY_SPACE:
+                        jumpRequested = isPressed;
+                        return;
+
+                    case GLFW.GLFW_KEY_W:
+                        walkRequested = isPressed;
+                        // This overrides the CameraInputProcessor.
+                        return;
+
+                    default:
+                }
+                super.onKeyboard(keyId, isPressed);
+            }
+        });
+    }
+
+    /**
+     * Configure lighting and the background color.
+     */
+    private void configureLighting() {
+        Vector4fc directColor = new Vector4f(0.3f, 0.3f, 0.3f, 1f);
+        setLightColor(directColor);
+
+        Vector3f direction = new Vector3f(7f, 3f, 5f);
+        setLightDirection(direction);
+
+        // Set the background color to light blue.
+        setBackgroundColor(Constants.SKY_BLUE);
+    }
+}