Replace visual breast physics with weighted deformation.

src/main/java/com/wildfire/physics/BreastPhysics.java

@@ -53,6 +53,8 @@ public class BreastPhysics {
 
 	private float breastSize = 0, preBreastSize = 0;
 
+	private float preVelocity;
+
 	private @Nullable Pose lastPose;
 	private int lastSwingDuration = 6, lastSwingTick = 0;
 	private @Nullable Vec3 prePos;
@@ -121,6 +123,7 @@ public void update(LivingEntity entity, IGenderArmor armor) {
 		this.prePositionX = this.positionX;
 		this.wfg_preBounceRotation = this.wfg_bounceRotation;
 		this.preBreastSize = this.breastSize;
+		this.preVelocity = this.velocity;
 
 		if(this.prePos == null) {
 			this.prePos = entity.position();
@@ -373,6 +376,13 @@ public float getPreBreastSize() {
 		return this.preBreastSize;
 	}
 
+	public float getVelocity() {
+		return this.velocity;
+	}
+	public float getPreVelocity() {
+		return this.preVelocity;
+	}
+
 	private int clampMovement(float movement) {
 		return Math.max((int) (10 - movement*2f), 1);
 	}

src/main/java/com/wildfire/render/BreastRenderCommand.java

@@ -37,21 +37,26 @@ public record BreastRenderCommand(
 		int overlay,
 		int color,
 		int outline,
-		@Nullable UnaryOperator<VertexConsumer> consumerOperator
+		@Nullable UnaryOperator<VertexConsumer> consumerOperator,
+		PhysicsDeformation physics
 ) implements SubmitNodeCollector.CustomGeometryRenderer {
 	public BreastRenderCommand(WildfireModelRenderer.ModelBox model, LivingEntityRenderState state, int overlay, int color) {
-		this(model, state.lightCoords, overlay, color, state.outlineColor, null);
+		this(model, state.lightCoords, overlay, color, state.outlineColor, null, PhysicsDeformation.NONE);
 	}
 
-	public static BreastRenderCommand trim(WildfireModelRenderer.ModelBox model, LivingEntityRenderState state, TextureAtlasSprite trimSprite) {
-		return new BreastRenderCommand(model, state.lightCoords, OverlayTexture.NO_OVERLAY, -1, 0, trimSprite::wrap);
+	public BreastRenderCommand(WildfireModelRenderer.ModelBox model, LivingEntityRenderState state, int overlay, int color, PhysicsDeformation physics) {
+		this(model, state.lightCoords, overlay, color, state.outlineColor, null, physics);
+	}
+
+	public static BreastRenderCommand trim(WildfireModelRenderer.ModelBox model, LivingEntityRenderState state, TextureAtlasSprite trimSprite, PhysicsDeformation physics) {
+		return new BreastRenderCommand(model, state.lightCoords, OverlayTexture.NO_OVERLAY, -1, 0, trimSprite::wrap, physics);
 	}
 
 	@Override
 	public void render(PoseStack.Pose matricesEntry, VertexConsumer vertexConsumer) {
 		if(consumerOperator != null) {
 			vertexConsumer = consumerOperator.apply(vertexConsumer);
 		}
-		GenderLayer.renderBox(model, matricesEntry, vertexConsumer, light, overlay, color);
+		GenderLayer.renderBox(model, matricesEntry, vertexConsumer, light, overlay, color, physics);
 	}
 }

src/main/java/com/wildfire/render/GenderArmorLayer.java

@@ -191,12 +191,14 @@ protected void renderBreastArmor(Identifier texture, PoseStack matrixStack, Subm
 			return;
 		}
 
+		PhysicsDeformation physics = createPhysicsDeformation(side);
+
 		var model = side.isLeft ? lBoobArmor : rBoobArmor;
 		var layer = RenderTypes.armorCutoutNoCull(texture);
-		queue.submitCustomGeometry(matrixStack, layer, new BreastRenderCommand(model, state, OverlayTexture.NO_OVERLAY, ARGB.opaque(color)));
+		queue.submitCustomGeometry(matrixStack, layer, new BreastRenderCommand(model, state, OverlayTexture.NO_OVERLAY, ARGB.opaque(color), physics));
 
 		if(glint) {
-			renderGlint(matrixStack, queue, state, model);
+			renderGlint(matrixStack, queue, state, model, side);
 		}
 	}
 
@@ -210,16 +212,19 @@ protected void renderArmorTrim(ResourceKey<EquipmentAsset> armorModel, PoseStack
 		var key = new EquipmentLayerRenderer.TrimSpriteKey(trim, EquipmentClientInfo.LayerType.HUMANOID, armorModel);
 		TextureAtlasSprite sprite = ((EquipmentLayerRendererAccessor) equipmentRenderer).getTrimSpriteLookup().apply(key);
 
+		PhysicsDeformation physics = createPhysicsDeformation(side);
+
 		var layer = Sheets.armorTrimsSheet(trim.pattern().value().decal());
-		queue.submitCustomGeometry(matrixStack, layer, BreastRenderCommand.trim(model, state, sprite));
+		queue.submitCustomGeometry(matrixStack, layer, BreastRenderCommand.trim(model, state, sprite, physics));
 
 		if(glint) {
-			renderGlint(matrixStack, queue, state, model);
+			renderGlint(matrixStack, queue, state, model, side);
 		}
 	}
 
-	protected void renderGlint(PoseStack matrixStack, SubmitNodeCollector renderQueue, S state, BreastModelBox box) {
+	protected void renderGlint(PoseStack matrixStack, SubmitNodeCollector renderQueue, S state, BreastModelBox box, BreastSide side) {
+		PhysicsDeformation physics = createPhysicsDeformation(side);
 		var glintLayer = RenderTypes.armorEntityGlint();
-		renderQueue.submitCustomGeometry(matrixStack, glintLayer, new BreastRenderCommand(box, state, OverlayTexture.NO_OVERLAY, -1));
+		renderQueue.submitCustomGeometry(matrixStack, glintLayer, new BreastRenderCommand(box, state, OverlayTexture.NO_OVERLAY, -1, physics));
 	}
 }

src/main/java/com/wildfire/render/GenderLayer.java

@@ -72,7 +72,7 @@ public class GenderLayer<S extends HumanoidRenderState, M extends HumanoidModel<
 	protected IGenderArmor genderArmor = IGenderArmor.EMPTY;
 	protected boolean isChestplateOccupied, bounceEnabled, breathingAnimation;
 	protected float breastOffsetX, breastOffsetY, breastOffsetZ, lPhysPositionY, lPhysPositionX, rPhysPositionY, rPhysPositionX,
-			lPhysBounceRotation, rPhysBounceRotation, breastSize, zOffset, outwardAngle;
+			lPhysBounceRotation, rPhysBounceRotation, lPhysVelocityY, rPhysVelocityY, breastSize, zOffset, outwardAngle;
 
 	public GenderLayer(RenderLayerParent<S, M> render) {
 		super(render);
@@ -155,15 +155,18 @@ protected boolean setupRender(S entityState, GenderRenderState genderState) {
 		lPhysPositionY = leftPhysicsState.getPositionY();
 		lPhysPositionX = leftPhysicsState.getPositionX();
 		lPhysBounceRotation = leftPhysicsState.getBounceRotation();
+		lPhysVelocityY = leftPhysicsState.getVelocityY();
 		if(isUniboob) {
 			rPhysPositionY = lPhysPositionY;
 			rPhysPositionX = lPhysPositionX;
 			rPhysBounceRotation = lPhysBounceRotation;
+			rPhysVelocityY = lPhysVelocityY;
 		} else {
 			GenderRenderState.BreastPhysicsState rightPhysicsState = genderState.rightBreastPhysics;
 			rPhysPositionY = rightPhysicsState.getPositionY();
 			rPhysPositionX = rightPhysicsState.getPositionX();
 			rPhysBounceRotation = rightPhysicsState.getBounceRotation();
+			rPhysVelocityY = rightPhysicsState.getVelocityY();
 		}
 
 		breastSize = Math.min(bSize * 1.5f, 0.7f); // Limit the max size to 0.7f
@@ -220,27 +223,15 @@ protected void setupTransformations(S state, M model, PoseStack matrixStack, Bre
 			matrixStack.mulPose(new Quaternionf().rotationZYX(body.zRot, body.yRot, body.xRot));
 		}
 
-		if(bounceEnabled) {
-			matrixStack.translate((side.isLeft ? lPhysPositionX : rPhysPositionX) / 32f, 0, 0);
-			matrixStack.translate(0, (side.isLeft ? lPhysPositionY : rPhysPositionY) / 32f, 0);
-		}
+		// physics translations now applied per-vertex in renderBox()
 
 		matrixStack.translate((side.isLeft ? breastOffsetX : -breastOffsetX) * 0.0625f, 0.05625f + (breastOffsetY * 0.0625f), zOffset - 0.0625f * 2f + (breastOffsetZ * 0.0425f)); //shift down to correct position
 
-		if(!isUniboob) {
-			matrixStack.translate(-0.0625f * 2 * (side.isLeft ? 1 : -1), 0, 0);
-		}
-		if(bounceEnabled) {
-			matrixStack.mulPose(new Quaternionf().rotationXYZ(0, (float)((side.isLeft ? lPhysBounceRotation : rPhysBounceRotation) * (Math.PI / 180f)), 0));
-		}
-		if(!isUniboob) {
-			matrixStack.translate(0.0625f * 2 * (side.isLeft ? 1 : -1), 0, 0);
-		}
+		// bounce Y-rotation now applied per-vertex in renderBox()
 
 		float rotation = breastSize;
 		if(bounceEnabled) {
 			matrixStack.translate(0, -0.035f * breastSize, 0); //shift down to correct position
-			rotation -= (side.isLeft ? lPhysPositionY : rPhysPositionY) / 12f;
 		}
 
 		rotation = Math.min(rotation, breastSize + 0.2f);
@@ -263,21 +254,34 @@ protected void setupTransformations(S state, M model, PoseStack matrixStack, Bre
 		matrixStack.scale(0.9995f, 1f, 1f); //z-fighting FIXXX
 	}
 
+	protected PhysicsDeformation createPhysicsDeformation(BreastSide side) {
+		if(!bounceEnabled) return PhysicsDeformation.NONE;
+		float bounceRotDeg = side.isLeft ? lPhysBounceRotation : rPhysBounceRotation;
+		return new PhysicsDeformation(
+			side.isLeft ? lPhysPositionX : rPhysPositionX,
+			side.isLeft ? lPhysPositionY : rPhysPositionY,
+			side.isLeft ? lPhysVelocityY : rPhysVelocityY,
+			bounceRotDeg * DEG_TO_RAD
+		);
+	}
+
 	private void renderBreast(S state, PoseStack matrixStack, SubmitNodeCollector queue, int overlay, BreastSide side) {
 		RenderType renderLayer = getRenderLayer(state);
 		if(renderLayer == null) return; // only render if the player is visible in some capacity
 
 		int alpha = state.isInvisible ? ARGB.as8BitChannel(0.15f) : 255;
 		int color = ARGB.color(alpha, 255, 255, 255);
 
+		PhysicsDeformation physics = createPhysicsDeformation(side);
+
 		var model = side.isLeft ? lBreast : rBreast;
-		queue.submitCustomGeometry(matrixStack, renderLayer, new BreastRenderCommand(model, state, overlay, color));
+		queue.submitCustomGeometry(matrixStack, renderLayer, new BreastRenderCommand(model, state, overlay, color, physics));
 
 		if(state instanceof AvatarRenderState playerState && playerState.showJacket) {
 			matrixStack.translate(0, 0, -0.015f);
 			matrixStack.scale(1.05f, 1.05f, 1.05f);
 			var jacketModel = side.isLeft ? lBreastWear : rBreastWear;
-			queue.submitCustomGeometry(matrixStack, renderLayer, new BreastRenderCommand(jacketModel, state, overlay, color));
+			queue.submitCustomGeometry(matrixStack, renderLayer, new BreastRenderCommand(jacketModel, state, overlay, color, physics));
 		}
 	}
 
@@ -300,14 +304,37 @@ protected void renderSides(S state, M model, PoseStack matrixStack, Consumer<Bre
 	}
 
 	public static void renderBox(WildfireModelRenderer.ModelBox model, PoseStack.Pose entry, VertexConsumer vertexConsumer,
-									int light, int overlay, int color) {
+									int light, int overlay, int color, PhysicsDeformation physics) {
 		Matrix4f matrix4f = entry.pose();
 		Matrix3f matrix3f = entry.normal();
+
+		// weight deformation by Y-distance: Y=posY1 (top) is attachment, Y=posY2 (bottom) is tip
+		float yMin = model.posY1;
+		float yRange = model.posY2 - model.posY1;
+		float physTransX = physics.offsetX() / 16f;
+		float physTransY = physics.offsetY() / 16f;
+		float physRotXRad = (physics.offsetY() / 8f) * 35f * DEG_TO_RAD;
+		float sinPhysRotX = (float) Math.sin(physRotXRad);
+		float cosPhysRotX = (float) Math.cos(physRotXRad);
+		// lateral sway as translation instead of rotation to prevent corners poking out
+		float avgZ = (model.posZ1 + model.posZ2) / 2f / 16f;
+		float physSwayX = (float) Math.sin(physics.bounceRotY()) * avgZ;
+		float stretchFactor = 1.0f + physics.velocityY() * 0.06f; //squash-and-stretch
+		stretchFactor = Mth.clamp(stretchFactor, 0.80f, 1.20f);
+
 		for(var quad : model.quads) {
 
 			//Make sure UVs aren't set to zero. If they are, the textures screw up. Don't render the quad at all.
 			if(quad.uvs[0] == 0.0F && quad.uvs[1] == 0.0F && quad.uvs[2] == 0.0F && quad.uvs[3] == 0.0F) continue;
 
+			//Skip the attachment face to avoid shadow acne
+			if(yRange > 0) {
+				var verts = quad.vertexPositions;
+				if(verts[0].y() == yMin && verts[1].y() == yMin && verts[2].y() == yMin && verts[3].y() == yMin) {
+					continue;
+				}
+			}
+
 			Vector3f vector3f = new Vector3f(quad.normal.x(), quad.normal.y(), quad.normal.z()).mul(matrix3f);
 			float normalX = vector3f.x;
 			float normalY = vector3f.y;
@@ -316,6 +343,28 @@ public static void renderBox(WildfireModelRenderer.ModelBox model, PoseStack.Pos
 				float j = vertex.x() / 16.0F;
 				float k = vertex.y() / 16.0F;
 				float l = vertex.z() / 16.0F;
+
+				//per-vertex weighted deformation: 0 at attachment (posY1), 1 at tip (posY2)
+				if(yRange > 0) {
+					float weight = Mth.clamp((vertex.y() - yMin) / yRange, 0f, 1f);
+
+					j += (physTransX + physSwayX) * weight;
+					k += physTransY * weight;
+
+					//weighted X-rotation tilt, pivots around attachment edge
+					{
+						float localY = k - (yMin / 16.0F);
+						float localZ = l;
+						float rotatedY = localY * cosPhysRotX - localZ * sinPhysRotX;
+						float rotatedZ = localZ * cosPhysRotX + localY * sinPhysRotX;
+						k = (yMin / 16.0F) + localY + (rotatedY - localY) * weight;
+						l = localZ + (rotatedZ - localZ) * weight;
+					}
+
+					float attachY = yMin / 16.0F; //squash-and-stretch from attachment
+					k = attachY + (k - attachY) * stretchFactor;
+				}
+
 				Vector4f vector4f = new Vector4f(j, k, l, 1.0F).mul(matrix4f);
 				vertexConsumer.addVertex(vector4f.x(), vector4f.y(), vector4f.z(), color, vertex.u(), vertex.v(),
 						overlay, light, normalX, normalY, normalZ);

src/main/java/com/wildfire/render/GenderRenderState.java

@@ -143,6 +143,7 @@ public class BreastPhysicsState {
 		private final float prePositionX, positionX;
 		private final float preBounceRotation, bounceRotation;
 		private final float preBreastSize, breastSize;
+		private final float preVelocity, velocityY;
 
 		private BreastPhysicsState(BreastPhysics breastPhysics) {
 			this.prePositionY = breastPhysics.getPrePositionY();
@@ -153,6 +154,8 @@ private BreastPhysicsState(BreastPhysics breastPhysics) {
 			this.bounceRotation = breastPhysics.getBounceRotation();
 			this.preBreastSize = breastPhysics.getPreBreastSize();
 			this.breastSize = breastPhysics.getBreastSize();
+			this.preVelocity = breastPhysics.getPreVelocity();
+			this.velocityY = breastPhysics.getVelocity();
 		}
 
 		public float getPositionY() {
@@ -170,5 +173,9 @@ public float getBounceRotation() {
 		public float getBreastSize() {
 			return Mth.lerp(partialTicks, this.preBreastSize, this.breastSize);
 		}
+
+		public float getVelocityY() {
+			return Mth.lerp(partialTicks, this.preVelocity, this.velocityY);
+		}
 	}
 }

src/main/java/com/wildfire/render/PhysicsDeformation.java

@@ -0,0 +1,44 @@
+/*
+ * Wildfire's Female Gender Mod is a female gender mod created for Minecraft.
+ * Copyright (C) 2023-present WildfireRomeo
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 3 of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program.  If not, see <https://www.gnu.org/licenses/>.
+ */
+
+package com.wildfire.render;
+
+import net.fabricmc.api.EnvType;
+import net.fabricmc.api.Environment;
+
+/**
+ * Per-vertex physics deformation parameters for breast rendering.
+ *
+ * <p>Instead of applying physics offsets as uniform translations (which moves the entire breast
+ * including the base that should stay attached to the body), these values are applied per-vertex
+ * weighted by the vertex's Y-distance from the attachment edge. This creates a natural bending/stretching
+ * effect where the base stays anchored and only the tip moves with the physics.</p>
+ *
+ * @param offsetX     Horizontal sway offset (from {@code BreastPhysics.positionX})
+ * @param offsetY     Vertical bounce offset (from {@code BreastPhysics.positionY})
+ * @param velocityY   Spring velocity for squash-and-stretch effect (from {@code BreastPhysics.velocity})
+ * @param bounceRotY  Y-axis bounce rotation in radians (lateral sway from {@code BreastPhysics.bounceRotation}).
+ *                    Applied per-vertex weighted so the attachment edge stays anchored.
+ */
+@Environment(EnvType.CLIENT)
+public record PhysicsDeformation(float offsetX, float offsetY, float velocityY, float bounceRotY) {
+	/**
+	 * A no-op deformation that applies no physics effects. Used when bounce physics are disabled.
+	 */
+	public static final PhysicsDeformation NONE = new PhysicsDeformation(0, 0, 0, 0);
+}