good system for shadertoy syntax integration. Close #3

src/kiss_flixel/ShaderFrontend.hx

@@ -4,61 +4,156 @@ import tink.syntaxhub.*;
 import haxe.macro.Expr;
 import haxe.macro.Context;
 import haxe.macro.Expr.ImportMode;
+import kiss.Stream;
+
 using StringTools;
 using tink.MacroApi;
 
 class ShaderFrontend implements FrontendPlugin {
- 
 	public function new() {}
-	
-    var vertexExtensions = ["v.glsl", "vert"]; 
-    var fragmentExtensions = ["f.glsl", "frag"];
+
+	var vertexExtensions = ["v.glsl", "vert"];
+	var fragmentExtensions = ["f.glsl", "frag"];
 
 	public function extensions() {
 		return vertexExtensions.concat(fragmentExtensions).iterator();
 	}
-	
+
 	public function parse(file:String, context:FrontendContext):Void {
-        var extension = file.substr(file.indexOf(".") + 1);
-        trace(extension);
+		var extension = file.substr(file.indexOf(".") + 1);
+		trace(extension);
 
 		final type = context.getType();
-        var parentClass = 'flixel.system.FlxAssets.FlxShader';
-        type.kind = TDClass(parentClass.asTypePath(), [], false, false, false);
+		var parentClass = 'flixel.system.FlxAssets.FlxShader';
+		type.kind = TDClass(parentClass.asTypePath(), [], false, false, false);
 
-        var pos = Context.makePosition({ file: file, min: 0, max: 0 });
-		
-        var metaName = if (vertexExtensions.contains(extension)) 
-            ":glVertexSource"
-        else if (fragmentExtensions.contains(extension))
-            ":glFragmentSource"
-        else
-            throw "Unknown extension";
+		var pos = Context.makePosition({file: file, min: 0, max: 0});
 
-        var meta = {
-            pos: pos,
-            name: metaName,
-            params: [
-                {
-                    pos: pos,
-                    expr: EConst(CString(sys.io.File.getContent(file)))
-                }
-            ]
-        };
+		var glslStream = Stream.fromFile(file);
 
-        type.fields.push({
-            pos: pos,
-            name: "new",
-            meta: [meta],
-            kind: FFun({
-                args: [],
-                expr: macro { super(); }
-            }),
-            access: [APublic]
-        });
+        var transformedCode = "";
+        function error(reason = "") {
+            throw 'Error transforming shader code! $reason';
+        }
+
+		// Supply ShaderToy-esque iTime
+		transformedCode += 'uniform float iTime = 0.0;\n';
+		type.fields.push({
+			pos: pos,
+			name: "__update",
+			kind: FFun({
+				args: [],
+				expr: macro {
+					super.__update();
+					data.iTime.value = [data.iTime.value[0] + flixel.FlxG.elapsed];
+				}
+			}),
+			access: [APublic, AOverride]
+		});
+
+		// TODO Implement round for the targets that weirdly don't have it
+
+		var delimiters = ",.(){}[] \t\n;?:|&<>/*+-'\"=".split("");
+
+		var colorOut = "";
+		var coordIn = "";
+
+
+        function nextToken() {
+            glslStream.dropWhitespace();
+            return glslStream.takeUntilOneOf(delimiters);
+        }
+
+        function dropNext(delim:String) {
+            glslStream.dropWhitespace();
+            glslStream.dropString(delim);
+        }
+
+		while (!glslStream.isEmpty()) {
+			switch (glslStream.takeWhileOneOf(delimiters)) {
+				case Some(codeSyntax):
+					transformedCode += codeSyntax;
+				default:
+			}
+			switch (glslStream.takeUntilOneOf(delimiters)) {
+                case Some("#pragma"):
+                    switch (nextToken()) {
+                        case Some("header"):
+                            // We already add #pragma header at the start of everything -- a duplicate creates an error
+                            continue;
+                        case Some(pragma):
+                            transformedCode += '#pragma $pragma';
+                        default:
+                    }
+
+				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(name) if (name == colorOut):
+                    transformedCode += "gl_FragColor";
+                case Some(name) if (name == coordIn):
+                    transformedCode += "openfl_TextureCoordv * openfl_TextureSize";
+
+				case Some(other):
+					transformedCode += other;
+				default:
+			}
+		}
+
+		transformedCode = "#pragma header\n" + transformedCode;
+
+		var metaName = if (vertexExtensions.contains(extension)) ":glVertexSource" else if (fragmentExtensions.contains(extension)) ":glFragmentSource" else
+			throw "Unknown extension";
+
+		var meta = {
+			pos: pos,
+			name: metaName,
+			params: [
+				{
+					pos: pos,
+					expr: EConst(CString(transformedCode))
+				}
+			]
+		};
+
+		type.fields.push({
+			pos: pos,
+			name: "new",
+			meta: [meta],
+			kind: FFun({
+				args: [],
+				expr: macro {
+					super();
+                    data.iTime.value = [0.0];
+				}
+			}),
+			access: [APublic]
+		});
 	}
 
 	static function use() {
 		tink.SyntaxHub.frontends.whenever(new ShaderFrontend());
 	}
-}
+}