From 0f1ad758e83796de5de1634ef415a8335a59df07 Mon Sep 17 00:00:00 2001
From: Rob Kelly <contact@robkel.ly>
Date: Sun, 21 Jul 2024 14:17:35 -0600
Subject: [PATCH] Hard-edge shader

---
 project.godot          |  6 +---
 src/hard_edge.gdshader | 64 ++++++++++++++++++++++++++++++++++++++++++
 src/main.tscn          | 28 ++++++++++++++++++
 3 files changed, 93 insertions(+), 5 deletions(-)
 create mode 100644 src/hard_edge.gdshader
 create mode 100644 src/main.tscn

diff --git a/project.godot b/project.godot
index 549a078..b1ec953 100644
--- a/project.godot
+++ b/project.godot
@@ -11,7 +11,7 @@ config_version=5
 [application]
 
 config/name="Sunstation"
-run/main_scene="res://src/maps/arena_map/arena_map.tscn"
+run/main_scene="res://src/main.tscn"
 config/features=PackedStringArray("4.2", "Forward Plus")
 run/max_fps=60
 
@@ -80,7 +80,3 @@ boost={
 , Object(InputEventJoypadButton,"resource_local_to_scene":false,"resource_name":"","device":-1,"button_index":2,"pressure":0.0,"pressed":true,"script":null)
 ]
 }
-
-[rendering]
-
-anti_aliasing/quality/msaa_3d=3
diff --git a/src/hard_edge.gdshader b/src/hard_edge.gdshader
new file mode 100644
index 0000000..fee8681
--- /dev/null
+++ b/src/hard_edge.gdshader
@@ -0,0 +1,64 @@
+/* Hard-edge shader
+ * Adapted from https://github.com/samuelbigos/godot_dither_shader
+ */
+
+shader_type canvas_item;
+
+// uniform sampler2D dither_tex;
+uniform sampler2D color_tex;
+
+uniform int bit_depth;
+uniform float contrast;
+uniform float offset;
+// uniform int dither_size;
+
+void fragment() {
+	//// sample the screen texture at the desired output resolution (according to dither_size)
+	//// this pixelates the output
+	//vec2 screen_size = vec2(textureSize(TEXTURE, 0)) / float(dither_size);
+	//vec2 screen_sample_uv = floor(UV * screen_size) / screen_size;
+	//vec3 screen_col = texture(TEXTURE, screen_sample_uv).rgb;
+	vec3 screen_col = texture(TEXTURE, UV).rgb;
+
+	// calculate pixel luminosity
+	float luminosity = (screen_col.r * 0.299) + (screen_col.g * 0.587) + (screen_col.b * 0.114);
+
+	// adjust contrast & offset
+	// XXX: need to redefine contrast???
+	luminosity = clamp((luminosity - 0.5 + offset) * contrast + 0.5, 0.0, 1.0);
+
+	// reduce luminosity bit depth to increase banding if desired
+	float b = float(bit_depth);
+	luminosity = floor(luminosity * b) / b;
+
+	// map palette texture to 1px high
+	ivec2 col_size = textureSize(color_tex, 0);
+	col_size /= col_size.y;
+
+	float col_x = float(col_size.x) - 1.0;
+	float col_texel_size = 1.0 / col_x;  // size of one color boundary
+
+	luminosity = max(luminosity - 0.00001, 0.0);  // fix for `floor` when luminosity == 1.0
+	float lum_lower = floor(luminosity * col_x) * col_texel_size;
+	float lum_upper = (floor(luminosity * col_x) + 1.0) * col_texel_size;
+	// fractional portion of scaled luminosity
+	float lum_scaled = luminosity * col_x - floor(luminosity * col_x);
+
+	//// map dither texture onto screen
+	//ivec2 noise_size = textureSize(dither_tex, 0);
+	//vec2 inv_noise_size = vec2(1.0 / float(noise_size.x), 1.0 / float(noise_size.y));
+	//vec2 noise_uv = UV * inv_noise_size * vec2(float(screen_size.x), float(screen_size.y));
+	//float threshold = texture(dither_tex, noise_uv).r;
+
+	//// add dither margins to allow fully dark and light dither patterns at edges of luminosity
+	//threshold = threshold * 0.99 + 0.005;
+
+	//// the lower lum_scaled is, the fewer pixels will be below the dither threshold,
+	//// and thus will use the lower bound color, and vice versa
+	//float ramp_val = lum_scaled < threshold ? 0.0f : 1.0f;
+	float ramp_val = lum_scaled < 0.5 ? 0.0f : 1.0f;
+	// sample at lower bound color if ramp_val is 0.0, upper bound color if 1.0
+	float col_sample = mix(lum_lower, lum_upper, ramp_val);
+
+	COLOR.rgb = texture(color_tex, vec2(col_sample, 0.5)).rgb;
+}
diff --git a/src/main.tscn b/src/main.tscn
new file mode 100644
index 0000000..f18bc76
--- /dev/null
+++ b/src/main.tscn
@@ -0,0 +1,28 @@
+[gd_scene load_steps=5 format=3 uid="uid://d75odchj18u1"]
+
+[ext_resource type="PackedScene" uid="uid://drbiyuustse8b" path="res://src/maps/arena_map/arena_map.tscn" id="1_bvhtq"]
+[ext_resource type="Shader" path="res://src/hard_edge.gdshader" id="1_y05i6"]
+[ext_resource type="Texture2D" uid="uid://deu1gf4gxbvvh" path="res://assets/palette_moonlight.png" id="2_uwrk1"]
+
+[sub_resource type="ShaderMaterial" id="ShaderMaterial_ab1b3"]
+shader = ExtResource("1_y05i6")
+shader_parameter/bit_depth = 32
+shader_parameter/contrast = 1.0
+shader_parameter/offset = null
+shader_parameter/color_tex = ExtResource("2_uwrk1")
+
+[node name="Main" type="Node3D"]
+
+[node name="ViewportContainer" type="SubViewportContainer" parent="."]
+material = SubResource("ShaderMaterial_ab1b3")
+custom_minimum_size = Vector2(1900, 768)
+offset_right = 1900.0
+offset_bottom = 768.0
+stretch = true
+
+[node name="Viewport" type="SubViewport" parent="ViewportContainer"]
+handle_input_locally = false
+size = Vector2i(1900, 768)
+render_target_update_mode = 4
+
+[node name="ArenaMap" parent="ViewportContainer/Viewport" instance=ExtResource("1_bvhtq")]