improvement: textures scale to size (#551)

* fix: textures scale to size

* fix: added EmptyComponent to whitelist

* improvement: graphics are more closely aligned with meshes

* docs: added documentation to the alignment code

* refactor: made Invisibility a field in Renderable component

* docs: cleaned up and added more documentation

engine/src/main/java/org/destinationsol/SolApplication.java

@@ -260,23 +260,24 @@ private void draw() {
 
             //TODO remove this block - it is for debugging purposes
             if (!entityCreated) {
+
+                Size size = new Size();
+                size.size = 2;
+
                 RenderableElement element = new RenderableElement();
                 element.texture = SolRandom.randomElement(Assets.listTexturesMatching("engine:asteroid_.*"));
-                element.relativePosition = new Vector2(0, 0);
+                element.relativePosition = new Vector2();
                 element.drawableLevel = DrawableLevel.BODIES;
-                element.width = 2;
-                element.height = 2;
                 element.tint = Color.YELLOW;
+                element.setSize(size.size);
+                element.graphicsOffset = new Vector2();
                 Renderable graphicsComponent = new Renderable();
                 graphicsComponent.elements.add(element);
 
                 Position position = new Position();
                 position.position = solGame.getHero().getShip().getPosition().cpy();
                 position.position.y += 3;
 
-                Size size = new Size();
-                size.size = 2;
-
                 Health health = new Health();
                 health.currentHealth = 1;
 

engine/src/main/java/org/destinationsol/asteroids/systems/AsteroidBodyCreationSystem.java

@@ -66,7 +66,6 @@ public class AsteroidBodyCreationSystem implements EventReceiver {
     @ReceiveEvent(components = {AsteroidMesh.class, Size.class, Position.class, Angle.class, Renderable.class})
     public EventResult onGenerateBody(GenerateBodyEvent event, EntityRef entity) {
 
-
         float size = entity.getComponent(Size.class).get().size;
         Vector2 position = entity.getComponent(Position.class).get().position;
         float angle = entity.getComponent(Angle.class).get().getAngle();
@@ -90,9 +89,29 @@ public EventResult onGenerateBody(GenerateBodyEvent event, EntityRef entity) {
             fixtureDef.density = DENSITY;
             fixtureDef.friction = Const.FRICTION;
             collisionMeshLoader.attachFixture(body, element.texture.name, fixtureDef, size);
+
+            calculateGraphicsOffset(element);
         }
 
         entitySystemManager.sendEvent(new BodyCreatedEvent(body), entity);
         return EventResult.CONTINUE;
     }
+
+    /**
+     * This calculates the offset of the renderable element from "the origin" (as defined in the JSON that the
+     * CollisionMeshLoader reads from).
+     * The origin is where the center of the object should be, which is relevant for physics handling. The
+     * CollisionMeshLoader creates Fixtures (collision meshes) using that information, so the sprites need to be
+     * adjusted to overlay the mesh properly.
+     * LibGDX draws sprites from the bottom left corner. Since the position information is from the center, it
+     * needs to be adjusted to be at the bottom left of the sprite. To do so, (.5, .5) is subtracted from the origin.
+     * (The coordinates are scaled to range from zero to one, so (.5, .5) represents the center.)
+     * The originInformation is the information that was read from the JSON, which is used to calculate the graphics
+     * offset information.
+     */
+    //TODO separate this method into a separate system once CollisionMeshLoader is modular
+    private void calculateGraphicsOffset(RenderableElement element) {
+        Vector2 originInformation = collisionMeshLoader.getOrigin(element.texture.name, 1);
+        element.graphicsOffset = new Vector2(originInformation.x - .5f, originInformation.y - .5f);
+    }
 }

engine/src/main/java/org/destinationsol/modules/ModuleManager.java

@@ -157,6 +157,7 @@ public class ModuleManager {
             java.io.PipedOutputStream.class,
             /* Gestalt classes */
             org.terasology.gestalt.entitysystem.component.Component.class,
+            org.terasology.gestalt.entitysystem.component.EmptyComponent.class,
             org.terasology.gestalt.entitysystem.event.Event.class,
             org.terasology.gestalt.entitysystem.entity.EntityRef.class,
             org.terasology.gestalt.entitysystem.entity.EntityIterator.class,

engine/src/main/java/org/destinationsol/rendering/RenderableElement.java

@@ -18,7 +18,9 @@
 import com.badlogic.gdx.graphics.Color;
 import com.badlogic.gdx.graphics.g2d.TextureAtlas;
 import com.badlogic.gdx.math.Vector2;
+import org.destinationsol.common.SolMath;
 import org.destinationsol.game.drawables.DrawableLevel;
+import org.destinationsol.size.components.Size;
 
 /**
  * Contains a {@link TextureAtlas.AtlasRegion} (an image), along with information about how it should be drawn.
@@ -29,10 +31,10 @@ public class RenderableElement {
     public TextureAtlas.AtlasRegion texture;
 
     /** The width of the texture when drawn. */
-    public float width;
+    private float width;
 
     /** The height of the texture when drawn. */
-    public float height;
+    private float height;
 
     /** Represents the depth at which this element renders, as well as its logical grouping. */
     public DrawableLevel drawableLevel;
@@ -46,14 +48,52 @@ public class RenderableElement {
     /** The tint that the texture should be given. */
     public Color tint;
 
+    /**
+     * The amount that the sprite should be moved to line up accurately with the mesh. This should be scaled according
+     * to the {@link Size}. This is different from the relativePosition, because this is a practical adjustment to align
+     * the mesh with the sprite, as opposed to moving the sprite relative to the base entity. To draw the sprite
+     * accurately, it needs to be drawn from the bottom-left of the actual image, not the bottom left of the .png file,
+     * so this contains the information for calculating the actual start of the sprite.
+     * <p>
+     * Modification of this can create mesh misalignments, so only change this if you know what you're doing.
+     */
+    public Vector2 graphicsOffset;
+
+
+    //TODO this should be automatically called when the Size component is changed, e.g. the entity shrinks or grows
+    /**
+     * Resizes the renderable element to the given size. The larger dimension of the texture is set to the size, and the
+     * smaller one is scaled down proportionally.
+     */
+    public void setSize(float size) {
+        size /= drawableLevel.depth; // Scales the texture size for objects that are in the background
+        float dimensionsRatio = (float) texture.getRegionWidth() / texture.getRegionHeight();
+        if (dimensionsRatio > 1) {
+            width = size;
+            height = size / dimensionsRatio;
+        } else {
+            width = size / dimensionsRatio;
+            height = size;
+        }
+    }
+
     public void copy(RenderableElement other) {
         this.texture = new TextureAtlas.AtlasRegion(other.texture);
         this.drawableLevel = other.drawableLevel;
         this.relativePosition = other.relativePosition.cpy();
         this.relativeAngle = other.relativeAngle;
-        this.width = other.width;
-        this.height = other.height;
+        this.width = other.getWidth();
+        this.height = other.getHeight();
         this.tint = other.tint.cpy();
+        this.graphicsOffset = other.graphicsOffset.cpy();
+    }
+
+    public float getWidth() {
+        return width;
+    }
+
+    public float getHeight() {
+        return height;
     }
 }
 

engine/src/main/java/org/destinationsol/rendering/components/Renderable.java

@@ -27,6 +27,8 @@ public final class Renderable implements Component<Renderable> {
 
     public ArrayList<RenderableElement> elements = new ArrayList<>();
 
+    public boolean isInvisible;
+
     @Override
     public void copy(Renderable other) {
         ArrayList<RenderableElement> newElements = new ArrayList<>();
@@ -37,5 +39,6 @@ public void copy(Renderable other) {
         }
 
         this.elements = newElements;
+        this.isInvisible = other.isInvisible;
     }
 }

engine/src/main/java/org/destinationsol/rendering/systems/RenderingSystem.java

@@ -19,13 +19,13 @@
 import org.destinationsol.common.In;
 import org.destinationsol.rendering.RenderableElement;
 import org.destinationsol.rendering.components.Renderable;
-import org.destinationsol.rendering.components.Invisible;
 import org.destinationsol.rendering.events.RenderEvent;
 import org.destinationsol.entitysystem.EntitySystemManager;
 import org.destinationsol.entitysystem.EventReceiver;
 import org.destinationsol.game.GameDrawer;
 import org.destinationsol.location.components.Angle;
 import org.destinationsol.location.components.Position;
+import org.destinationsol.size.components.Size;
 import org.terasology.gestalt.entitysystem.entity.EntityRef;
 import org.terasology.gestalt.entitysystem.event.EventResult;
 import org.terasology.gestalt.entitysystem.event.ReceiveEvent;
@@ -41,13 +41,14 @@ public class RenderingSystem implements EventReceiver {
     @In
     private GameDrawer drawer;
 
-    @ReceiveEvent(components = {Renderable.class, Position.class})
+    @ReceiveEvent(components = {Renderable.class, Position.class, Size.class})
     public EventResult onRender(RenderEvent event, EntityRef entity) {
 
-        if (!entity.hasComponent(Invisible.class)) {
+        Renderable renderable = entity.getComponent(Renderable.class).get();
+        if (!renderable.isInvisible) {
 
-            Renderable renderable = entity.getComponent(Renderable.class).get();
             Vector2 basePosition = entity.getComponent(Position.class).get().position;
+            float size = entity.getComponent(Size.class).get().size;
 
             float baseAngle = 0;
             if (entity.hasComponent(Position.class)) {
@@ -56,10 +57,20 @@ public EventResult onRender(RenderEvent event, EntityRef entity) {
 
             for (RenderableElement renderableElement : renderable.elements) {
                 float angle = renderableElement.relativeAngle + baseAngle;
+                Vector2 renderableElementPosition = basePosition.add(renderableElement.relativePosition);
 
-                drawer.draw(renderableElement.texture, renderableElement.width,
-                        renderableElement.height, renderableElement.width / 2, renderableElement.height / 2,
-                        basePosition.x, basePosition.y, angle, renderableElement.tint);
+                /*
+                This calculates how much the position of the drawable should be shifted horizontally or vertically to
+                line up with the collision mesh.
+                 */
+                float horizontalShift = renderableElement.getWidth() / 2;
+                float verticalShift = renderableElement.getHeight() / 2;
+                horizontalShift += renderableElement.graphicsOffset.x * size;
+                verticalShift += renderableElement.graphicsOffset.y * size;
+
+                drawer.draw(renderableElement.texture, renderableElement.getWidth(), renderableElement.getHeight(),
+                        horizontalShift, verticalShift, renderableElementPosition.x, renderableElementPosition.y, angle,
+                        renderableElement.tint);
             }
         }