add basic heat transfer #4

Reviewed-on: #9

half-earth/Half-earth.csproj

@@ -0,0 +1,6 @@
+<Project Sdk="Godot.NET.Sdk/3.3.0">
+  <PropertyGroup>
+    <TargetFramework>net472</TargetFramework>
+    <RootNamespace>Halfearth</RootNamespace>
+  </PropertyGroup>
+</Project>

half-earth/Half-earth.sln

@@ -0,0 +1,19 @@
+Microsoft Visual Studio Solution File, Format Version 12.00
+# Visual Studio 2012
+Project("{FAE04EC0-301F-11D3-BF4B-00C04F79EFBC}") = "Half-earth", "Half-earth.csproj", "{C894A75C-991B-4000-9BD9-9B0B186304C4}"
+EndProject
+Global
+	GlobalSection(SolutionConfigurationPlatforms) = preSolution
+	Debug|Any CPU = Debug|Any CPU
+	ExportDebug|Any CPU = ExportDebug|Any CPU
+	ExportRelease|Any CPU = ExportRelease|Any CPU
+	EndGlobalSection
+	GlobalSection(ProjectConfigurationPlatforms) = postSolution
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.Debug|Any CPU.ActiveCfg = Debug|Any CPU
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.Debug|Any CPU.Build.0 = Debug|Any CPU
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.ExportDebug|Any CPU.ActiveCfg = ExportDebug|Any CPU
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.ExportDebug|Any CPU.Build.0 = ExportDebug|Any CPU
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.ExportRelease|Any CPU.ActiveCfg = ExportRelease|Any CPU
+		{C894A75C-991B-4000-9BD9-9B0B186304C4}.ExportRelease|Any CPU.Build.0 = ExportRelease|Any CPU
+	EndGlobalSection
+EndGlobal

half-earth/materials/cursor.tres

@@ -0,0 +1,9 @@
+[gd_resource type="ShaderMaterial" load_steps=2 format=2]
+
+[ext_resource path="res://shaders/tile_shader.gdshader" type="Shader" id=1]
+
+[resource]
+shader = ExtResource( 1 )
+shader_param/lowColor = Color( 1, 0.960784, 0, 1 )
+shader_param/highColor = Color( 0.921569, 0, 1, 1 )
+shader_param/t = null

half-earth/materials/tile.tres

@@ -0,0 +1,10 @@
+[gd_resource type="ShaderMaterial" load_steps=2 format=2]
+
+[ext_resource path="res://shaders/tile_shader.gdshader" type="Shader" id=1]
+
+[resource]
+resource_local_to_scene = true
+shader = ExtResource( 1 )
+shader_param/lowColor = Color( 0, 0, 0, 1 )
+shader_param/highColor = Color( 1, 0.560784, 0, 1 )
+shader_param/t = null

half-earth/nodes/clock.tscn

@@ -0,0 +1,6 @@
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://scripts/Clock.cs" type="Script" id=1]
+
+[node name="Clock" type="Node"]
+script = ExtResource( 1 )

half-earth/nodes/debug_ui.tscn

@@ -0,0 +1,22 @@
+[gd_scene load_steps=2 format=2]
+
+[ext_resource path="res://scripts/DebugUI.cs" type="Script" id=1]
+
+[node name="Debug UI" type="Control"]
+anchor_right = 1.0
+anchor_bottom = 1.0
+script = ExtResource( 1 )
+TicksLabelPath = NodePath("Ticks")
+
+[node name="Ticks" type="Label" parent="."]
+anchor_left = 1.0
+anchor_top = 1.0
+anchor_right = 1.0
+anchor_bottom = 1.0
+margin_right = -10.0
+margin_bottom = -10.0
+grow_horizontal = 0
+grow_vertical = 0
+text = "ticks: 0"
+align = 2
+valign = 2

half-earth/nodes/game.tscn

@@ -0,0 +1,20 @@
+[gd_scene load_steps=5 format=2]
+
+[ext_resource path="res://nodes/grid.tscn" type="PackedScene" id=1]
+[ext_resource path="res://nodes/grid_cursor.tscn" type="PackedScene" id=2]
+[ext_resource path="res://nodes/debug_ui.tscn" type="PackedScene" id=3]
+[ext_resource path="res://nodes/clock.tscn" type="PackedScene" id=4]
+
+[node name="Root" type="Node"]
+
+[node name="Grid" parent="." instance=ExtResource( 1 )]
+
+[node name="Cursor" parent="." instance=ExtResource( 2 )]
+Grid = NodePath("../Grid")
+
+[node name="Debug UI" parent="." instance=ExtResource( 3 )]
+
+[node name="Clock" parent="." instance=ExtResource( 4 )]
+
+[connection signal="OnTick" from="Clock" to="Grid" method="_on_Clock_OnTick"]
+[connection signal="OnTick" from="Clock" to="Debug UI" method="_on_Clock_OnTick"]

half-earth/nodes/grid.tscn

@@ -0,0 +1,10 @@
+[gd_scene load_steps=3 format=2]
+
+[ext_resource path="res://scripts/WorldGrid.cs" type="Script" id=1]
+[ext_resource path="res://nodes/tile.tscn" type="PackedScene" id=2]
+
+[node name="Grid" type="Node2D"]
+script = ExtResource( 1 )
+TileScene = ExtResource( 2 )
+Size = 10
+CellSize = 64

half-earth/nodes/grid_cursor.tscn

@@ -0,0 +1,10 @@
+[gd_scene load_steps=4 format=2]
+
+[ext_resource path="res://textures/icon.png" type="Texture" id=1]
+[ext_resource path="res://scripts/GridCursor.cs" type="Script" id=2]
+[ext_resource path="res://materials/cursor.tres" type="Material" id=3]
+
+[node name="Grid Cursor" type="Sprite"]
+material = ExtResource( 3 )
+texture = ExtResource( 1 )
+script = ExtResource( 2 )

half-earth/nodes/tile.tscn

@@ -0,0 +1,8 @@
+[gd_scene load_steps=3 format=2]
+
+[ext_resource path="res://materials/tile.tres" type="Material" id=1]
+[ext_resource path="res://textures/icon.png" type="Texture" id=2]
+
+[node name="Tile" type="Sprite"]
+material = ExtResource( 1 )
+texture = ExtResource( 2 )

half-earth/project.godot

@@ -11,7 +11,8 @@ config_version=4
 [application]
 
 config/name="Half-earth"
-config/icon="res://icon.png"
+run/main_scene="res://nodes/game.tscn"
+config/icon="res://textures/icon.png"
 
 [gui]
 
@@ -27,4 +28,5 @@ common/enable_pause_aware_picking=true
 
 [rendering]
 
-environment/default_environment="res://default_env.tres"
+gles3/shaders/shader_compilation_mode=1
+environment/default_environment="res://resources/default_env.tres"

half-earth/scripts/Clock.cs

@@ -0,0 +1,31 @@
+using Godot;
+using System;
+
+public class Clock : Node
+{
+    [Signal]
+    delegate void OnTick(int ticks);
+    
+    private int _ticks = 0;
+
+    public override void _Input(InputEvent @event)
+    {
+        base._Input(@event);
+
+        if (@event is InputEventKey keyEvent && keyEvent.Pressed)
+        {
+            switch ((KeyList)keyEvent.Scancode)
+            {
+                case KeyList.Space:
+                    Tick();
+                    break;
+            }
+        }
+    }
+    
+    private void Tick()
+    {
+        _ticks++;
+        EmitSignal(nameof(OnTick), _ticks);
+    }
+}

half-earth/scripts/DebugUI.cs

@@ -0,0 +1,22 @@
+using Godot;
+using System;
+
+public class DebugUI : Control
+{
+    [Export]
+    public NodePath TicksLabelPath { private get; set; }
+    private Label _ticksLabel;
+    
+    public override void _Ready()
+    {
+        _ticksLabel = GetNode<Label>(TicksLabelPath);
+        SetTicksText(0);
+    }
+    
+    public void _on_Clock_OnTick(int ticks) => SetTicksText(ticks);
+    
+    private void SetTicksText(int ticks)
+    {
+        _ticksLabel.Text = $"ticks: {ticks}";
+    }
+}

half-earth/scripts/GridCursor.cs

@@ -0,0 +1,51 @@
+using Godot;
+using System;
+
+public class GridCursor : Sprite
+{
+    [Export]
+    public NodePath Grid { get; set; }
+    private WorldGrid _grid;
+    private ShaderMaterial _material;
+
+    private const string T = "t";
+
+    public override void _Ready()
+    {
+        _grid = GetNode<WorldGrid>(Grid);
+        _material = (ShaderMaterial)Material;
+    }
+
+    public override void _Input(InputEvent @event)
+    {
+        base._Input(@event);
+
+        if (@event is InputEventMouseMotion mouseMoveEvent)
+        {
+            var pos = mouseMoveEvent.Position;
+            _grid.GetGridPos(pos, out var x, out var y);
+            this.Visible = _grid.IsInBounds(x, y);
+            var position = new Vector2(x + .5f, y + .5f) * _grid.CellSize;
+            this.Position = position;
+        }
+        else if (@event is InputEventMouseButton mouseButtonEvent)
+        {
+            switch ((ButtonList)mouseButtonEvent.ButtonIndex)
+            {
+                case ButtonList.Left:
+                    if (mouseButtonEvent.Pressed)
+                    {
+                        var pos = mouseButtonEvent.Position;
+                        _grid.GetGridPos(pos, out var x, out var y);
+                        _grid.SetTileValue(x, y, 1.0f);
+                        _material.SetShaderParam(T, 1f);
+                    }
+                    else
+                    {
+                        _material.SetShaderParam(T, 0f);
+                    }
+                    break;
+            }
+        }
+    }
+}

half-earth/scripts/Tile.cs

@@ -0,0 +1,8 @@
+using Godot;
+
+public struct Tile
+{
+    public bool isHighlighted;
+    public float value;
+    public ShaderMaterial material;
+}

half-earth/scripts/WorldGrid.cs

@@ -0,0 +1,168 @@
+using Godot;
+using System;
+using System.Collections.Generic;
+
+public class WorldGrid : Node2D
+{
+    [Export]
+    private PackedScene TileScene { get; set; }
+
+    [Export]
+    public int Size { get; set; }
+
+    [Export]
+    public int CellSize { get; set; }
+
+    [Export]
+    public float DiffusionCoefficient { get; set; } = 0.01f;
+
+    private Tile[,] _tiles;
+    private float[,] _nextValues = null;
+
+    // Called when the node enters the scene tree for the first time.
+    public override void _Ready()
+    {
+        GenerateGrid(Size);
+    }
+
+    public override void _Process(float delta)
+    {
+        base._Process(delta);
+
+        for (int x = 0; x < Size; x++)
+        {
+            for (int y = 0; y < Size; y++)
+            {
+                var tile = _tiles[x, y];
+                var material = tile.material;
+                material.SetShaderParam("t", tile.value);
+            }
+        }
+    }
+
+    public bool IsInBounds(int x, int y)
+    {
+        return x >= 0 && x < Size && y >= 0 && y < Size;
+    }
+
+    public void ToggleTileHighlight(int x, int y)
+    {
+        if (!IsInBounds(x, y))
+            return;
+
+        _tiles[x, y].isHighlighted ^= true;
+    }
+
+    public void SetTileValue(int x, int y, float value)
+    {
+        _tiles[x, y].value = value;
+    }
+
+    public void GetGridPos(Vector2 position, out int x, out int y)
+    {
+        x = Mathf.FloorToInt(position.x / CellSize);
+        y = Mathf.FloorToInt(position.y / CellSize);
+    }
+
+    private void Clear()
+    {
+        _tiles = null;
+
+        int children = this.GetChildCount();
+        GD.Print(children);
+        for (int i = 0; i < children; i++)
+        {
+            var child = this.GetChild(i);
+            child.QueueFree();
+        }
+    }
+
+    private void GenerateGrid(int size)
+    {
+        this.Clear();
+
+        _tiles = new Tile[size, size];
+        _nextValues = new float[size, size];
+
+        for (int x = 0; x < size; x++)
+        {
+            for (int y = 0; y < size; y++)
+            {
+                var tile = new Tile();
+                tile.isHighlighted = false;
+                tile.value = 0.0f;
+
+                var node = TileScene.Instance<Node2D>();
+                this.AddChild(node);
+                var position = new Vector2
+                {
+                    x = (x + .5f) * CellSize,
+                    y = (y + .5f) * CellSize
+                };
+                node.Position = position;
+                var canvasItem = (CanvasItem)node;
+                tile.material = (ShaderMaterial)canvasItem.Material;
+
+                _tiles[x, y] = tile;
+            }
+        }
+    }
+
+    public void _on_Clock_OnTick(int ticks)
+    {
+        Diffuse();
+    }
+
+    private float TransferHeat(float t0, float alpha, float nx, float ny, float px, float py)
+    {
+        float d2tdx2 = nx - 2 * t0 + px;
+        float d2tdy2 = ny - 2 * t0 + py;
+        return t0 + alpha * (d2tdx2 + d2tdy2);
+    }
+
+    private void GetNeighbourTemperatures(int x, int y, out float nx, out float ny, out float px, out float py)
+    {
+        // default value
+        var t = _tiles[x, y].value;
+
+        nx = x > 0 ? _tiles[x - 1, y].value : t;
+        px = x < Size - 1 ? _tiles[x + 1, y].value : t;
+
+        ny = y > 0 ? _tiles[x, y - 1].value : t;
+        py = y < Size - 1 ? _tiles[x, y + 1].value : t;
+    }
+
+    private void Diffuse()
+    {
+
+        for (int x = 0; x < Size; x++)
+        {
+            for (int y = 0; y < Size; y++)
+            {
+                float t = _tiles[x, y].value;
+                var D = DiffusionCoefficient;
+
+                GetNeighbourTemperatures(
+                    x, y,
+                    out var nx,
+                    out var ny,
+                    out var px,
+                    out var py);
+
+                // current value
+                _nextValues[x, y] = TransferHeat(t, D, nx, ny, px, py);
+            }
+        }
+
+        float sum = 0f;
+        for (int x = 0; x < Size; x++)
+        {
+            for (int y = 0; y < Size; y++)
+            {
+                _tiles[x, y].value = _nextValues[x, y];
+                sum += _tiles[x, y].value;
+            }
+        }
+        GD.Print(sum);
+    }
+}

half-earth/shaders/tile_shader.gdshader

@@ -0,0 +1,9 @@
+shader_type canvas_item;
+
+uniform vec4 lowColor : hint_color;
+uniform vec4 highColor : hint_color;
+uniform float t;
+
+void fragment() {
+	COLOR = mix(lowColor, highColor, t);
+}

half-earth/textures/icon.png.import

@@ -2,15 +2,15 @@
 
 importer="texture"
 type="StreamTexture"
-path="res://.import/icon.png-487276ed1e3a0c39cad0279d744ee560.stex"
+path="res://.import/icon.png-f931f6b997c470ed41f337ac62349254.stex"
 metadata={
 "vram_texture": false
 }
 
 [deps]
 
-source_file="res://icon.png"
-dest_files=[ "res://.import/icon.png-487276ed1e3a0c39cad0279d744ee560.stex" ]
+source_file="res://textures/icon.png"
+dest_files=[ "res://.import/icon.png-f931f6b997c470ed41f337ac62349254.stex" ]
 
 [params]