MineLittlePony/src/main/java/com/minelittlepony/client/render/EquineRenderManager.java

package com.minelittlepony.client.render;

import com.minelittlepony.client.MineLittlePony;
import com.minelittlepony.client.model.IPonyModel;
import com.minelittlepony.client.model.ModelWrapper;
import com.minelittlepony.client.transform.PonyPosture;
import com.minelittlepony.mson.api.ModelKey;
import com.minelittlepony.pony.IPony;
import com.minelittlepony.util.MathUtil;
import com.mojang.blaze3d.platform.GlStateManager.DestFactor;
import com.mojang.blaze3d.platform.GlStateManager.SourceFactor;
import com.mojang.blaze3d.systems.RenderSystem;

import javax.annotation.Nonnull;

import net.minecraft.client.render.Frustum;
import net.minecraft.client.render.entity.model.EntityModel;
import net.minecraft.client.util.math.MatrixStack;
import net.minecraft.entity.Entity;
import net.minecraft.entity.LivingEntity;
import net.minecraft.util.Identifier;

public class EquineRenderManager<T extends LivingEntity, M extends EntityModel<T> & IPonyModel<T>> {

    public ModelWrapper<T, M> playerModel;

    private IPony pony;

    private final IPonyRenderContext<T, M> renderer;

    private boolean skipBlend;

    private final FrustrumCheck<T> frustrum = new FrustrumCheck<>(this);

    public static void enableModelRenderProfile(boolean skipBlend) {
        RenderSystem.enableBlend();
        if (!skipBlend) {
            RenderSystem.blendFunc(SourceFactor.SRC_ALPHA, DestFactor.ONE_MINUS_SRC_ALPHA);
        }
        RenderSystem.alphaFunc(516, 0.003921569F);
    }

    public static void disableModelRenderProfile() {
        RenderSystem.disableBlend();
    }

    public EquineRenderManager(IPonyRenderContext<T, M> renderer) {
        this.renderer = renderer;
    }

    public void setSkipBlend() {
        skipBlend = true;
    }

    public Frustum getFrustrum(T entity, Frustum vanilla) {
        if (entity.isSleeping() || !MineLittlePony.getInstance().getConfig().frustrum.get()) {
            return vanilla;
        }
        return frustrum.withCamera(entity, vanilla);
    }

    public void preRenderCallback(T entity, MatrixStack stack, float ticks) {
        updateModel(entity, Mode.THIRD_PERSON);

        float s = getScaleFactor();
        stack.scale(s, s, s);
        enableModelRenderProfile(skipBlend);

        translateRider(entity, stack, ticks);
    }

    public float getRenderYaw(T entity, float rotationYaw, float partialTicks) {
        if (entity.hasVehicle()) {
            Entity mount = entity.getVehicle();
            if (mount instanceof LivingEntity) {
                return MathUtil.interpolateDegress(((LivingEntity) mount).prevBodyYaw, ((LivingEntity) mount).bodyYaw, partialTicks);
            }
        }

        return rotationYaw;
    }

    protected void translateRider(T entity, MatrixStack stack, float ticks) {
        if (entity.hasVehicle() && entity.getVehicle() instanceof LivingEntity) {

            LivingEntity ridingEntity = (LivingEntity) entity.getVehicle();
            IPonyRenderContext<LivingEntity, ?> renderer = PonyRenderDispatcher.getInstance().getPonyRenderer(ridingEntity);

            if (renderer != null) {
                // negate vanilla translations so the rider begins at the ridees feet.
                stack.translate(0, -ridingEntity.getHeight(), 0);

                IPony riderPony = renderer.getEntityPony(ridingEntity);

                renderer.translateRider(ridingEntity, riderPony, entity, pony, stack, ticks);
            }
        }
    }

    @SuppressWarnings("unchecked")
    public void applyPostureTransform(T player, MatrixStack stack, float yaw, float ticks) {
        ((PonyPosture<T>) getPosture(player)).apply(player, getModel(), stack, yaw, ticks, 1);
    }

    @SuppressWarnings("unchecked")
    public void applyPostureRiding(T player, MatrixStack stack, float yaw, float ticks) {
        ((PonyPosture<T>) getPosture(player)).apply(player, getModel(), stack, yaw, ticks, -1);
    }

    @Nonnull
    private PonyPosture<?> getPosture(T entity) {
        if (entity.isFallFlying()) {
            return PonyPosture.ELYTRA;
        }

        if (entity.isAlive() && entity.isSleeping()) {
            return PonyPosture.DEFAULT;
        }

        if (getModel().getAttributes().isSwimming) {
            return PonyPosture.SWIMMING;
        }

        if (getModel().getAttributes().isGoingFast) {
            return PonyPosture.FLIGHT;
        }

        return PonyPosture.FALLING;
    }

    public M getModel() {
        return playerModel.getBody();
    }

    public ModelWrapper<T, M> setModel(ModelKey<?> key) {
        playerModel = new ModelWrapper<>(key);

        return playerModel;
    }

    public void updateMetadata(Identifier texture) {
        pony = MineLittlePony.getInstance().getManager().getPony(texture);
        playerModel.apply(pony.getMetadata());
    }

    public void updateModel(T entity, Mode mode) {
        pony = renderer.getEntityPony(entity);
        playerModel.apply(pony.getMetadata());
        pony.updateForEntity(entity);

        getModel().updateLivingState(entity, pony, mode);
    }

    public IPony getPony(T entity) {
        updateModel(entity, Mode.THIRD_PERSON);
        return pony;
    }

    public float getShadowScale() {
        return getModel().getSize().getShadowSize();
    }

    public float getScaleFactor() {
        return getModel().getSize().getScaleFactor();
    }

    public double getNamePlateYOffset(T entity) {

        // We start by negating the height calculation done by mahjong.
        float y = -(entity.getHeight() + 0.5F - (entity.isInSneakingPose() ? 0.25F : 0));

        // Then we add our own offsets.
        y += getModel().getAttributes().visualHeight * getScaleFactor() + 0.25F;

        if (entity.isSneaking()) {
            y -= 0.25F;
        }

        if (entity.hasVehicle()) {
            y += entity.getVehicle().getEyeHeight(entity.getPose());
        }

        if (entity.isSleeping()) {
            y /= 2;
        }

        return y;
    }

    public enum Mode {
        FIRST_PERSON,
        THIRD_PERSON
    }
}