From 6edf50c4f67c2ac2e8c81fa7e2dd5d6d72217a41 Mon Sep 17 00:00:00 2001
From: Cory Petkovsek <632766+TokisanGames@users.noreply.github.com>
Date: Thu, 16 Nov 2023 01:30:08 +0700
Subject: [PATCH] Enable texture brushing w/ new control map format

---
 src/terrain_3d_editor.cpp | 53 ++++++++++++++++++++++++++-------------
 1 file changed, 35 insertions(+), 18 deletions(-)

diff --git a/src/terrain_3d_editor.cpp b/src/terrain_3d_editor.cpp
index a2364a661..f21735e09 100644
--- a/src/terrain_3d_editor.cpp
+++ b/src/terrain_3d_editor.cpp
@@ -203,31 +203,48 @@ void Terrain3DEditor::_operate_map(Vector3 p_global_position, real_t p_camera_di
 					storage->update_heights(destf);
 
 				} else if (map_type == Terrain3DStorage::TYPE_CONTROL) {
+					// Get bit field from pixel
+					uint32_t bits;
+					*(real_t *)&bits = src.r;
+					uint32_t base_index = bits >> 27u & 0x1Fu;
+					uint32_t overlay_index = bits >> 22u & 0x1Fu;
+					real_t blend = real_t(bits >> 14u & 0xFFu) / 255.0f;
+
 					real_t alpha_clip = (brush_alpha < 0.1f) ? 0.0f : 1.0f;
-					int index_base = int(src.r * 255.0f);
-					int index_overlay = int(src.g * 255.0f);
-					int dest_index = 0;
+					uint32_t dest_index = int(Math::lerp(base_index, texture_id, alpha_clip));
 
 					switch (_operation) {
-						case Terrain3DEditor::ADD:
+						case Terrain3DEditor::REPLACE: {
+							// Base Paint
+							base_index = dest_index;
+							blend = Math::lerp(real_t(blend), real_t(0.0f), alpha_clip * opacity);
+						} break;
+						case Terrain3DEditor::ADD: {
 							// Spray Overlay
-							dest_index = int(Math::lerp(index_overlay, texture_id, alpha_clip));
-							if (dest_index == index_base) {
-								dest.b = Math::lerp(real_t(src.b), real_t(0.0f), alpha_clip * opacity * real_t(0.5f));
+							real_t spray_opacity = CLAMP(opacity * real_t(0.025f), real_t(0.003f), real_t(0.025f));
+							real_t brush_value = CLAMP(brush_alpha * spray_opacity, real_t(0.0f), real_t(1.0f));
+							if (dest_index == base_index) {
+								blend = CLAMP(blend - brush_value, real_t(0.0f), real_t(1.0f));
 							} else {
-								dest.g = dest_index / 255.0f;
-								dest.b = Math::lerp(real_t(src.b), CLAMP(src.b + brush_alpha, real_t(0.0f), real_t(1.0f)), brush_alpha * opacity * real_t(0.5f));
+								overlay_index = dest_index;
+								blend = CLAMP(blend + brush_value, real_t(0.0f), real_t(1.0f));
 							}
-							break;
-						case Terrain3DEditor::REPLACE:
-							// Base Paint
-							dest_index = int(Math::lerp(index_base, texture_id, alpha_clip));
-							dest.r = dest_index / 255.0f;
-							dest.b = Math::lerp(real_t(src.b), real_t(0.0f), alpha_clip * opacity);
-							break;
-						default:
-							break;
+						} break;
+						default: {
+						} break;
 					}
+
+					// Convert back to bit field
+					uint32_t base = (base_index & 0x1F) << 27; // 5 bits 32-28
+					uint32_t over = (overlay_index & 0x1F) << 22; // 5 bits 27-23
+					uint32_t blend_int = uint32_t(CLAMP(Math::round(blend * 255.0f), 0.0f, 255.0f));
+					blend_int = (blend_int & 0xFF) << 14; // 8 bits 22-15
+					bits = base | over | blend_int;
+
+					// Write back to pixel in FORMAT_RF
+					real_t out_float = *(real_t *)&bits;
+					dest = Color(out_float, 0.f, 0.f, 1.0f);
+
 				} else if (map_type == Terrain3DStorage::TYPE_COLOR) {
 					switch (_tool) {
 						case COLOR: