Undo Previous PR on Gambatte Colors and Implement an Option (#1918)

* Revert "New GBC LCD correction for Gambatte palette from documented shader research https://forums.libretro.com/t/real-gba-and-ds-phat-colors/1540"

This reverts commit 88cda24876.

* Implement the libretro GBC color palette as an added option instead of a change to the Gambatte option

BizHawk.Client.EmuHawk/config/GB/CGBColorChooserForm.Designer.cs

@@ -39,12 +39,14 @@
             this.bmpView1 = new BizHawk.Client.EmuHawk.BmpView();
             this.buttonOK = new System.Windows.Forms.Button();
             this.buttonCancel = new System.Windows.Forms.Button();
+            this.radioButton7 = new System.Windows.Forms.RadioButton();
             this.groupBox1.SuspendLayout();
             this.groupBox2.SuspendLayout();
             this.SuspendLayout();
             // 
             // groupBox1
             // 
+            this.groupBox1.Controls.Add(this.radioButton7);
             this.groupBox1.Controls.Add(this.radioButton6);
             this.groupBox1.Controls.Add(this.radioButton5);
             this.groupBox1.Controls.Add(this.radioButton3);
@@ -57,6 +59,7 @@
             this.groupBox1.TabIndex = 0;
             this.groupBox1.TabStop = false;
             this.groupBox1.Text = "Preset Select";
+            this.groupBox1.Enter += new System.EventHandler(this.groupBox1_Enter);
             // 
             // radioButton6
             // 
@@ -170,6 +173,18 @@
             this.buttonCancel.Text = "Cancel";
             this.buttonCancel.UseVisualStyleBackColor = true;
             // 
+            // radioButton7
+            // 
+            this.radioButton7.AutoSize = true;
+            this.radioButton7.Location = new System.Drawing.Point(6, 157);
+            this.radioButton7.Name = "radioButton7";
+            this.radioButton7.Size = new System.Drawing.Size(85, 17);
+            this.radioButton7.TabIndex = 4;
+            this.radioButton7.TabStop = true;
+            this.radioButton7.Text = "Libretro GBC";
+            this.radioButton7.UseVisualStyleBackColor = true;
+			this.radioButton7.CheckedChanged += new System.EventHandler(this.RadioButton1_CheckedChanged);
+			// 
 			// CGBColorChooserForm
 			// 
 			this.AcceptButton = this.buttonOK;
@@ -182,7 +197,6 @@
             this.Controls.Add(this.groupBox2);
             this.Controls.Add(this.groupBox1);
             this.FormBorderStyle = System.Windows.Forms.FormBorderStyle.FixedSingle;
-			this.Icon = global::BizHawk.Client.EmuHawk.Properties.Resources.gambatte_MultiSize;
             this.Name = "CGBColorChooserForm";
             this.StartPosition = System.Windows.Forms.FormStartPosition.CenterParent;
             this.Text = "Game Boy Color Palette Config";
@@ -206,5 +220,6 @@
 		private System.Windows.Forms.Button buttonOK;
 		private System.Windows.Forms.Button buttonCancel;
 		private System.Windows.Forms.RadioButton radioButton6;
+		private System.Windows.Forms.RadioButton radioButton7;
 	}
 }

BizHawk.Client.EmuHawk/config/GB/CGBColorChooserForm.cs

@@ -39,6 +39,9 @@ namespace BizHawk.Client.EmuHawk
 				case GBColors.ColorType.gba:
 					radioButton6.Checked = true;
 					break;
+				case GBColors.ColorType.libretrogbc:
+					radioButton7.Checked = true;
+					break;
 			}
 		}
 
@@ -101,6 +104,11 @@ namespace BizHawk.Client.EmuHawk
 				_type = GBColors.ColorType.gba;
 			}
 
+			if (sender == radioButton7)
+			{
+				_type = GBColors.ColorType.libretrogbc;
+			}
+
 			if (sender is RadioButton radioButton && radioButton.Checked)
 			{
 				RefreshType();
@@ -117,5 +125,10 @@ namespace BizHawk.Client.EmuHawk
 				s.CGBColors = dlg._type;
 			}
 		}
+
+		private void groupBox1_Enter(object sender, EventArgs e)
+		{
+
+		}
 	}
 }

BizHawk.Emulation.Cores/Consoles/Nintendo/Gameboy/GBColors.cs

@@ -51,6 +51,18 @@ namespace BizHawk.Emulation.Cores.Nintendo.Gameboy
 		public static Triple GambatteColor(Triple c)
 		{
 			Triple ret;
+			ret.r = (c.r * 13 + c.g * 2 + c.b) >> 1;
+			ret.g = (c.g * 3 + c.b) << 1;
+			ret.b = (c.r * 3 + c.g * 2 + c.b * 11) >> 1;
+			return ret;
+		}
+
+		public static Triple LibretroGBCColor(Triple c)
+		{
+			Triple ret;
+			ret.r = (c.r * 13 + c.g * 2 + c.b) >> 1;
+			ret.g = (c.g * 3 + c.b) << 1;
+			ret.b = (c.r * 3 + c.g * 2 + c.b * 11) >> 1;
 			double gammaR = Math.Pow((double)c.r / 31, 2.2);
 			double gammaG = Math.Pow((double)c.g / 31, 2.2);
 			double gammaB = Math.Pow((double)c.b / 31, 2.2);
@@ -130,7 +142,8 @@ namespace BizHawk.Emulation.Cores.Nintendo.Gameboy
 			vbavivid,
 			vbagbnew,
 			vbabgbold,
-			gba
+			gba,
+			libretrogbc
 		}
 
 		public static int[] GetLut(ColorType c)
@@ -151,6 +164,7 @@ namespace BizHawk.Emulation.Cores.Nintendo.Gameboy
 				case ColorType.vbagbnew: f = NewVBAColor; break;
 				case ColorType.vbabgbold: f = OldVBAColor; break;
 				case ColorType.gba: f = GBAColor; break;
+				case ColorType.libretrogbc: f = LibretroGBCColor; break;
 			}
 
 			int i = 0;