[shgraph] proper var codegen

hrt/shgraph/nodes/ShaderVar.hx

@@ -2,5 +2,4 @@ package hrt.shgraph.nodes;
 
 abstract class ShaderVar extends ShaderNode {
 	@prop() public var varId : Int = 0;
-	var graph: Graph;
 }

hrt/shgraph/nodes/VarRead.hx

@@ -19,7 +19,7 @@ class VarRead extends ShaderVar {
 	}
 
 	override function generate(ctx:NodeGenContext) {
-		var out = AstTools.makeVar(ctx.getLocalTVar("_sg_var_write", TVec(4, VFloat)));
+		var out = AstTools.makeVar(ctx.getLocalTVar('_sg_var_$varId', TVec(4, VFloat)));
 		ctx.setOutput(0, out);
 		#if editor
 		ctx.addPreview(out);

hrt/shgraph/nodes/VarWrite.hx

@@ -19,7 +19,7 @@ class VarWrite extends ShaderVar {
 
 	override function generate(ctx:NodeGenContext) {
 		var input = ctx.getInput(0);
-		ctx.addExpr(AstTools.makeVarDecl(ctx.getLocalTVar("_sg_var_write", TVec(4, VFloat)), input));
+		ctx.addExpr(AstTools.makeVarDecl(ctx.getLocalTVar('_sg_var_$varId', TVec(4, VFloat)), input));
 		ctx.addPreview(input);
 	}