Added #include_once shader directive and circular inclusion detection

src/renderers/webgl/WebGLProgram.js

@@ -158,21 +158,53 @@ function replaceClippingPlaneNums( string, parameters ) {
 
 }
 
-function parseIncludes( string ) {
+function parseIncludes( string, stack, stackMap, alreadyIncluded ) {
 
-	var pattern = /^[ \t]*#include +<([\w\d./]+)>/gm;
+	var pattern = /^[ \t]*#include(_once|) +<([\w\d./]+)>/gm;
 
-	function replace( match, include ) {
+	if ( stack === undefined ) {
+
+		stack = [];
+		alreadyIncluded = {};
+		stackMap = {};
+
+	}
+
+	function replace( match, once, include ) {
+
+		if ( once.length !== 0 && alreadyIncluded[ include ] === true ) {
+
+			return '';
+
+		}
+
+		if ( stackMap[ include ] === true ) {
+
+			throw new Error(
+				'Circular #include' + once + ' <' + include + '> detected!\n(\n\t' + stack.join( '\n\t' ) + '\n)'
+			);
+
+		}
 
 		var replace = ShaderChunk[ include ];
 
 		if ( replace === undefined ) {
 
-			throw new Error( 'Can not resolve #include <' + include + '>' );
+			throw new Error(
+				'Can not resolve #include' + once + ' <' + include + '>'
+					+ ( stack.length !== 0 ? '\n(\n\t' + stack.join( '\n\t' ) + '\n)' : '' )
+			);
 
 		}
 
-		return parseIncludes( replace );
+		stack.push( include );
+		stackMap[ include ] = true;
+		alreadyIncluded[ include ] = true;
+		var result = parseIncludes( replace, stack, stackMap, alreadyIncluded );
+		stack.pop();
+		stackMap[ include ] = false;
+
+		return result;
 
 	}
 
@@ -727,4 +759,4 @@ function WebGLProgram( renderer, extensions, code, material, shader, parameters,
 
 }
 
-export { WebGLProgram };
+export { WebGLProgram, parseIncludes };

test/unit/src/renderers/webgl/WebGLProgram.tests.js

@@ -3,7 +3,31 @@
  */
 /* global QUnit */
 
-import { WebGLProgram } from '../../../../../src/renderers/webgl/WebGLProgram';
+import { parseIncludes } from '../../../../../src/renderers/webgl/WebGLProgram';
+import { ShaderChunk } from '../../../../../src/renderers/shaders/ShaderChunk';
+
+function copyShaderChunks( chunks ) {
+
+	var copy = {};
+	for ( var k in chunks ) {
+
+		copy[ k ] = chunks[ k ];
+
+	}
+
+	return copy;
+
+}
+
+function merge( target, source ) {
+
+	for ( var k in source ) {
+
+		target[ k ] = source[ k ];
+
+	}
+
+}
 
 export default QUnit.module( 'Renderers', () => {
 
@@ -50,6 +74,61 @@ export default QUnit.module( 'Renderers', () => {
 
 			} );
 
+			QUnit.test( "parseIncludes", ( assert ) => {
+
+				var testChunks = {
+					test_chunk_a: [
+						"#chunk_a#"
+					].join( "\n" ),
+					test_chunk_b: [
+						"#include_once <test_chunk_a>",
+						"#include_once <test_chunk_f>",
+						"#include_once <test_chunk_a>"
+					].join( "\n" ),
+					test_chunk_c: [
+						"#include <test_chunk_a>",
+						"#include <test_chunk_d>"
+					].join( "\n" ),
+					test_chunk_d: [
+						"#include <test_chunk_e>",
+						"#include <test_chunk_a>"
+					].join( "\n" ),
+					test_chunk_e: [
+						"#include <test_chunk_c>",
+						"#include <test_chunk_a>"
+					].join( "\n" ),
+					test_chunk_f: [
+						"#chunk_f#"
+					].join( "\n" )
+				};
+				merge( ShaderChunk, testChunks );
+				var testStack = [ "test_chunk_c", "test_chunk_d", "test_chunk_e" ];
+				assert.throws(
+					() => {
+
+						parseIncludes( "#include_once <test_chunk_c>" );
+
+					},
+					new Error(
+						'Circular #include <test_chunk_c> detected!\n(\n\t' + testStack.join( '\n\t' ) + '\n)'
+					),
+					"throws error on circular dependencies"
+				);
+
+				assert.equal(
+					parseIncludes(
+						"#include <test_chunk_b>"
+					),
+					[
+						"#chunk_a#",
+						"#chunk_f#",
+						""
+					].join( "\n" ),
+					"multiple include_once of the same library get only included once"
+				);
+
+			} );
+
 		} );
 
 	} );