Add depth map export (closes #371)

src/main/java/com/replaymod/render/mixin/Mixin_PreserveDepthDuringHandRendering.java

@@ -0,0 +1,24 @@
+package com.replaymod.render.mixin;
+
+import com.replaymod.render.hooks.EntityRendererHandler;
+import net.minecraft.client.render.GameRenderer;
+import org.lwjgl.opengl.GL11;
+import org.spongepowered.asm.mixin.Mixin;
+import org.spongepowered.asm.mixin.injection.At;
+import org.spongepowered.asm.mixin.injection.ModifyArg;
+
+@Mixin(GameRenderer.class)
+public abstract class Mixin_PreserveDepthDuringHandRendering {
+    @ModifyArg(
+            method = "renderWorld",
+            at = @At(value = "INVOKE", target = "Lcom/mojang/blaze3d/systems/RenderSystem;clear(IZ)V"),
+            index = 0
+    )
+    private int replayModRender_skipClearWhenRecordingDepth(int mask) {
+        EntityRendererHandler handler = ((EntityRendererHandler.IEntityRenderer) this).replayModRender_getHandler();
+        if (handler != null && handler.getSettings().isDepthMap()) {
+            mask = mask & ~GL11.GL_DEPTH_BUFFER_BIT;
+        }
+        return mask;
+    }
+}