Snow effect with custom colors

Author: maddie480

Ahorn/effects/customSnow.jl

@@ -0,0 +1,13 @@
+module SpringCollab2020CustomSnow
+
+using ..Ahorn, Maple
+
+@mapdef Effect "SpringCollab2020/CustomSnow" CustomSnow(only::String="*", exclude::String="", color::String="FFFFFF,FFFFFF")
+
+placements = CustomSnow
+
+function Ahorn.canFgBg(effect::CustomSnow)
+    return true, true
+end
+
+end

Ahorn/lang/en_gb.lang

@@ -327,3 +327,6 @@ placements.triggers.SpringCollab2020/BadelineBounceDirectionTrigger.tooltips.bou
 # Wall Booster
 placements.entities.SpringCollab2020/NonCoreModeWallBooster.tooltips.left=Whether the entity attaches to the left wall or not.
 placements.entities.SpringCollab2020/NonCoreModeWallBooster.tooltips.notCoreMode=Determines whether the entity should ignore the current core mode and default to ice variant.
+
+# Custom Snow
+placements.effects.SpringCollab2020/CustomSnow.tooltips.colors=Comma-separated list of all colors the particles can take from.

Effects/CustomSnow.cs

@@ -0,0 +1,27 @@
+using Microsoft.Xna.Framework;
+using MonoMod.Utils;
+using System;
+using System.Reflection;
+
+namespace Celeste.Mod.SpringCollab2020.Effects {
+    public class CustomSnow : Snow {
+        private static MethodInfo particleInit = typeof(Snow).GetNestedType("Particle", BindingFlags.NonPublic).GetMethod("Init");
+
+        public CustomSnow(Color[] colors, bool foreground) : base(foreground) {
+            DynData<Snow> selfData = new DynData<Snow>(this);
+
+            // redo the same operations as the vanilla constructor, but with our custom set of colors.
+            selfData["colors"] = colors;
+            selfData["blendedColors"] = new Color[colors.Length];
+            Array particles = selfData.Get<Array>("particles");
+            int speedMin = foreground ? 120 : 40;
+            int speedMax = foreground ? 300 : 100;
+            for (int i = 0; i < particles.Length; i++) {
+                // Particle is a private struct, so getting it gets a copy that we should set back afterwards.
+                object particle = particles.GetValue(i);
+                particleInit.Invoke(particle, new object[] { colors.Length, speedMin, speedMax });
+                particles.SetValue(particle, i);
+            }
+        }
+    }
+}

SpringCollab2020Module.cs

@@ -2,6 +2,7 @@
 using Celeste.Mod.SpringCollab2020.Entities;
 using Celeste.Mod.SpringCollab2020.Triggers;
 using Microsoft.Xna.Framework;
+using Monocle;
 using System;
 
 namespace Celeste.Mod.SpringCollab2020 {
@@ -94,6 +95,15 @@ private Backdrop onLoadBackdrop(MapData map, BinaryPacker.Element child, BinaryP
             if (child.Name.Equals("SpringCollab2020/HeatWaveNoColorGrade", StringComparison.OrdinalIgnoreCase)) {
                 return new HeatWaveNoColorGrade();
             }
+            if (child.Name.Equals("SpringCollab2020/CustomSnow", StringComparison.OrdinalIgnoreCase)) {
+                string[] colorsAsStrings = child.Attr("colors").Split(',');
+                Color[] colors = new Color[colorsAsStrings.Length];
+                for (int i = 0; i < colors.Length; i++) {
+                    colors[i] = Calc.HexToColor(colorsAsStrings[i]);
+                }
+
+                return new CustomSnow(colors, child.AttrBool("foreground"));
+            }
             return null;
         }