From 3741e0eecf724c42c99d43bd0c466576ad378210 Mon Sep 17 00:00:00 2001
From: Nat Quayle Nelson <natquaylenelson@gmail.com>
Date: Sun, 31 Mar 2024 22:11:55 -0600
Subject: [PATCH] actual Godot compatibility changes

---
 shader-test/source/PlayState.kiss             |  2 +-
 src/kiss_flixel/ShaderFrontend.hx             | 66 +++++++++++++------
 .../shaders}/MirroredOrnament.frag            |  0
 3 files changed, 46 insertions(+), 22 deletions(-)
 rename {shader-test/source => src/kiss_flixel/shaders}/MirroredOrnament.frag (100%)

diff --git a/shader-test/source/PlayState.kiss b/shader-test/source/PlayState.kiss
index 9af80cd..6e70998 100644
--- a/shader-test/source/PlayState.kiss
+++ b/shader-test/source/PlayState.kiss
@@ -17,7 +17,7 @@
         (bg.screenCenter)
         (set bg.alpha 0.5)
         (add bg))
-    (set shader (new MirroredOrnament))
+    (set shader (new kiss_flixel.shaders.MirroredOrnament))
     // (set shader.data.invert.value [true])
     // (set shader.data.color1.value [1.0 1.0 1.0 1.0])
     // (set shader.data.color2.value [0.0 0.0 0.0 1.0])
diff --git a/src/kiss_flixel/ShaderFrontend.hx b/src/kiss_flixel/ShaderFrontend.hx
index 123714e..5e6651e 100644
--- a/src/kiss_flixel/ShaderFrontend.hx
+++ b/src/kiss_flixel/ShaderFrontend.hx
@@ -102,6 +102,7 @@ class ShaderFrontend implements FrontendPlugin {
 		var colorOut = "";
 		var coordIn = "";
 
+		transformedCode += "const float PI = 3.1415926535897932384626433832795;\n";
 
         function nextToken() {
             glslStream.dropWhitespace();
@@ -132,36 +133,59 @@ class ShaderFrontend implements FrontendPlugin {
                         default:
                     }
 
+				// Shadertoy compatibility:
 				case Some("iResolution"):
 					transformedCode += "openfl_TextureSize";
 
-                case Some("mainImage"):
-                    dropNext("(");
-                    dropNext("out");
-                    dropNext("vec4");
-                    switch (nextToken()) {
-                        case Some(symbol):
-                            colorOut = symbol;
-                        default:
-                            error();
-                    }
-                    dropNext(",");
-                    dropNext("in");
-                    dropNext("vec2");
-                    switch (nextToken()) {
-                        case Some(symbol):
-                            coordIn = symbol;
-                        default:
-                            error();
-                    }
-                    dropNext(")");
-                    transformedCode += "main() ";
+				case Some("void"):
+					switch (nextToken()) {
+						case Some("mainImage"):
+							dropNext("(");
+							dropNext("out");
+							dropNext("vec4");
+							switch (nextToken()) {
+								case Some(symbol):
+									colorOut = symbol;
+								default:
+									error();
+							}
+							dropNext(",");
+							dropNext("in");
+							dropNext("vec2");
+							switch (nextToken()) {
+								case Some(symbol):
+									coordIn = symbol;
+								default:
+									error();
+							}
+							dropNext(")");
+							transformedCode += "void main() ";
+						case Some("fragment"):
+							dropNext("()");
+							transformedCode += "void main() ";
+						case Some(other):
+							transformedCode += 'void $other';
+						default:
+							throw "expected name of void function";
+					}
 
                 case Some(name) if (name == colorOut):
                     transformedCode += "gl_FragColor";
                 case Some(name) if (name == coordIn):
                     transformedCode += "openfl_TextureCoordv * openfl_TextureSize";
 
+				// Godot compatibility
+				case Some("TIME"):
+					transformedCode += "iTime";
+				case Some("COLOR"):
+					transformedCode += "gl_FragColor";
+				
+				// Not totally sure this actually is a 1-to-1 equivalency:
+				case Some("SCREEN_UV"):
+					transformedCode += "openfl_TextureCoordv";
+				case Some("SCREEN_PIXEL_SIZE"):
+					transformedCode += "vec2(1 / openfl_TextureSize.x, 1 / openfl_TextureSize.y)";
+
 				case Some("uniform"):
 					var uType = expect("uniform type", nextToken);
 
diff --git a/shader-test/source/MirroredOrnament.frag b/src/kiss_flixel/shaders/MirroredOrnament.frag
similarity index 100%
rename from shader-test/source/MirroredOrnament.frag
rename to src/kiss_flixel/shaders/MirroredOrnament.frag