From e85618a27c09e74dc79b19f8df4edd89d5b6eded Mon Sep 17 00:00:00 2001
From: Jonas Herzig <me@johni0702.de>
Date: Tue, 29 Jun 2021 12:48:38 +0200
Subject: [PATCH] Change frame time (used by Iris) to be based on replay or
 video time

Iris derives that one from the frameStartNanos argument passed to the render
method and shaders usually use it to do animations. Prior to this commit we
always pass 0 which effectively froze any shader animations.

With this commit, we now compute the frameStartNanos based on the
FPS of the video we are rendering (so animations will happen in real time when
watching the video) or based on the time in the replay (so animations will
be influenced by playback speed / be frozen if the replay is frozen).
We default to the video time based approach because the replay time one may
produce undesirable results when it comes to things like motion blur and TAA.
---
 .../java/com/replaymod/render/Setting.java    |  2 ++
 .../render/hooks/EntityRendererHandler.java   | 25 +++++++++++++++----
 2 files changed, 22 insertions(+), 5 deletions(-)

diff --git a/src/main/java/com/replaymod/render/Setting.java b/src/main/java/com/replaymod/render/Setting.java
index d8426126..c8a58037 100644
--- a/src/main/java/com/replaymod/render/Setting.java
+++ b/src/main/java/com/replaymod/render/Setting.java
@@ -7,4 +7,6 @@ public final class Setting<T> {
             new SettingsRegistry.SettingKeys<>("advanced", "renderPath", null, "./replay_videos/");
     public static final SettingsRegistry.SettingKey<Boolean> SKIP_POST_RENDER_GUI =
             new SettingsRegistry.SettingKeys<>("advanced", "skipPostRenderGui", null, false);
+    public static final SettingsRegistry.SettingKey<Boolean> FRAME_TIME_FROM_WORLD_TIME =
+            new SettingsRegistry.SettingKeys<>("render", "frameTimeFromWorldTime", null, false);
 }
diff --git a/src/main/java/com/replaymod/render/hooks/EntityRendererHandler.java b/src/main/java/com/replaymod/render/hooks/EntityRendererHandler.java
index 20e10c07..8dbd50f7 100644
--- a/src/main/java/com/replaymod/render/hooks/EntityRendererHandler.java
+++ b/src/main/java/com/replaymod/render/hooks/EntityRendererHandler.java
@@ -1,22 +1,22 @@
 package com.replaymod.render.hooks;
 
+import com.replaymod.core.ReplayMod;
 import com.replaymod.core.events.PreRenderHandCallback;
 import com.replaymod.core.versions.MCVer;
 import com.replaymod.render.RenderSettings;
+import com.replaymod.render.Setting;
 import com.replaymod.render.capturer.CaptureData;
 import com.replaymod.render.capturer.RenderInfo;
 import com.replaymod.render.capturer.WorldRenderer;
+import com.replaymod.replay.ReplayModReplay;
 import de.johni0702.minecraft.gui.utils.EventRegistrations;
 import net.minecraft.client.MinecraftClient;
 import net.minecraft.client.gui.screen.Screen;
 
-//#if MC>=11500
-import net.minecraft.client.util.math.MatrixStack;
-//#endif
-
 //#if MC>=11400
 import com.replaymod.core.events.PostRenderCallback;
 import com.replaymod.core.events.PreRenderCallback;
+import net.minecraft.util.Util;
 //#else
 //#if MC>=11400
 //$$ import net.minecraftforge.fml.hooks.BasicEventHooks;
@@ -38,10 +38,18 @@ public class EntityRendererHandler extends EventRegistrations implements WorldRe
 
     public boolean omnidirectional;
 
+    private final long startTime;
+
     public EntityRendererHandler(RenderSettings settings, RenderInfo renderInfo) {
         this.settings = settings;
         this.renderInfo = renderInfo;
 
+        //#if MC>=11400
+        this.startTime = Util.getMeasuringTimeNano();
+        //#else
+        //$$ this.startTime = System.nanoTime();
+        //#endif
+
         on(PreRenderHandCallback.EVENT, () -> omnidirectional);
 
         ((IEntityRenderer) mc.gameRenderer).replayModRender_setHandler(this);
@@ -51,7 +59,14 @@ public class EntityRendererHandler extends EventRegistrations implements WorldRe
     @Override
     public void renderWorld(final float partialTicks, CaptureData data) {
         this.data = data;
-        renderWorld(partialTicks, 0);
+        long offsetMillis;
+        if (ReplayMod.instance.getSettingsRegistry().get(Setting.FRAME_TIME_FROM_WORLD_TIME)) {
+            offsetMillis = ReplayModReplay.instance.getReplayHandler().getReplaySender().currentTimeStamp();
+        } else {
+            offsetMillis = renderInfo.getFramesDone() * 1_000L / settings.getFramesPerSecond();
+        }
+        long frameStartTimeNano = startTime + offsetMillis * 1_000_000L;
+        renderWorld(partialTicks, frameStartTimeNano);
     }
 
     public void renderWorld(float partialTicks, long finishTimeNano) {