diff --git a/main.go b/main.go
index deac646..928b183 100644
--- a/main.go
+++ b/main.go
@@ -7,6 +7,7 @@ import (
 
 	"sfdl/parser"
 	"sfdl/scanner"
+	"sfdl/semantices"
 )
 
 func main() {
@@ -14,15 +15,24 @@ func main() {
 		fmt.Println("usage: sfdl <source-file>")
 		return
 	}
-
 	filename := os.Args[1]
+
 	sc, err := scanner.NewScannerFromFile(filename)
 	if err != nil {
 		log.Fatalf("open file failed: %v", err)
 	}
 
+	// 初始化语义状态 & 画布
+	parser.ResetState()
+	semantices.InitCanvas()
+
 	p := parser.NewParser(sc)
 	p.Parse()
 
-	fmt.Println("Parse OK.")
+	// 保存图片
+	outFile := "out.png"
+	if err := semantices.SavePNG(outFile); err != nil {
+		log.Fatalf("save png failed: %v", err)
+	}
+	fmt.Println("Done. output:", outFile)
 }
diff --git a/parser/parser.go b/parser/parser.go
index f255ce2..f4efad8 100644
--- a/parser/parser.go
+++ b/parser/parser.go
@@ -144,9 +144,7 @@ func (p *Parser) parseOriginStatement() {
 	yExpr := p.parseExpression()
 	p.match(scanner.R_BRACKET)
 
-	// todo:
-	// semantices.SetOrigin(xExpr, yExpr)
-	fmt.Println("Parsed ORIGIN", xExpr, yExpr)
+	originStatement(xExpr, yExpr)
 }
 
 // SCALE IS ( Expression , Expression )
@@ -159,7 +157,7 @@ func (p *Parser) parseScaleStatement() {
 	yExpr := p.parseExpression()
 	p.match(scanner.R_BRACKET)
 
-	fmt.Println("Parsed SCALE", xExpr, yExpr)
+	scaleStatement(xExpr, yExpr)
 }
 
 // ROT IS Expression
@@ -168,7 +166,7 @@ func (p *Parser) parseRotStatement() {
 	p.match(scanner.IS)
 	angleExpr := p.parseExpression()
 
-	fmt.Println("Parsed ROT", angleExpr)
+	rotStatement(angleExpr)
 }
 
 // FOR T FROM Expression TO Expression STEP Expression
@@ -190,8 +188,5 @@ func (p *Parser) parseForStatement() {
 	yExpr := p.parseExpression()
 	p.match(scanner.R_BRACKET)
 
-	fmt.Println("Parsed FOR", start, end, step, xExpr, yExpr)
-
-	// todo:
-	// semantices.DrawLoop(start, end, step, xExpr, yExpr)
+	forStatement(start, end, step, xExpr, yExpr)
 }
diff --git a/parser/semantices.go b/parser/semantices.go
new file mode 100644
index 0000000..83c4aa4
--- /dev/null
+++ b/parser/semantices.go
@@ -0,0 +1,101 @@
+package parser
+
+import (
+	"math"
+
+	"sfdl/scanner"
+	"sfdl/semantices"
+)
+
+var (
+	Parameter        float64 // T
+	OriginX, OriginY float64
+	ScaleX, ScaleY   float64 = 1, 1
+	RotAngle         float64 // 弧度
+)
+
+func ResetState() {
+	Parameter = 0
+	OriginX, OriginY = 0, 0
+	ScaleX, ScaleY = 1, 1
+	RotAngle = 0
+}
+
+func evalExpr(root *ExprNode) float64 {
+	if root == nil {
+		return 0
+	}
+	switch root.Op {
+	case scanner.PLUS:
+		return evalExpr(root.Left) + evalExpr(root.Right)
+	case scanner.MINUS:
+		return evalExpr(root.Left) - evalExpr(root.Right)
+	case scanner.MUL:
+		return evalExpr(root.Left) * evalExpr(root.Right)
+	case scanner.DIV:
+		return evalExpr(root.Left) / evalExpr(root.Right)
+	case scanner.POWER:
+		return math.Pow(evalExpr(root.Left), evalExpr(root.Right))
+	case scanner.FUNC:
+		return root.Func(evalExpr(root.Left))
+	case scanner.CONST_ID:
+		return root.Value
+	case scanner.T:
+		return Parameter
+	default:
+		return 0
+	}
+}
+
+func calcCoord(xExpr, yExpr *ExprNode) (float64, float64) {
+	x := evalExpr(xExpr)
+	y := evalExpr(yExpr)
+
+	// scale
+	x *= ScaleX
+	y *= ScaleY
+
+	// rotate
+	tx := x*math.Cos(RotAngle) + y*math.Sin(RotAngle)
+	ty := y*math.Cos(RotAngle) - x*math.Sin(RotAngle)
+	x, y = tx, ty
+
+	// translate
+	x += OriginX
+	y += OriginY
+
+	return x, y
+}
+
+// ORIGIN IS (x, y)
+func originStatement(xExpr, yExpr *ExprNode) {
+	OriginX = evalExpr(xExpr)
+	OriginY = evalExpr(yExpr)
+}
+
+// SCALE IS (sx, sy)
+func scaleStatement(xExpr, yExpr *ExprNode) {
+	ScaleX = evalExpr(xExpr)
+	ScaleY = evalExpr(yExpr)
+}
+
+// ROT IS angle
+func rotStatement(angleExpr *ExprNode) {
+	RotAngle = evalExpr(angleExpr)
+}
+
+// FOR T FROM start TO end STEP step DRAW (xExpr, yExpr)
+func forStatement(startExpr, endExpr, stepExpr, xExpr, yExpr *ExprNode) {
+	start := evalExpr(startExpr)
+	end := evalExpr(endExpr)
+	step := evalExpr(stepExpr)
+
+	if step <= 1e-9 {
+		return
+	}
+
+	for Parameter = start; Parameter <= end; Parameter += step {
+		x, y := calcCoord(xExpr, yExpr)
+		semantices.DrawPixel(int(math.Round(x)), int(math.Round(y)))
+	}
+}
diff --git a/semantices/draw.go b/semantices/draw.go
index 9123ae2..c9a778e 100644
--- a/semantices/draw.go
+++ b/semantices/draw.go
@@ -1 +1,47 @@
 package semantices
+
+import (
+	"image"
+	"image/color"
+	"image/png"
+	"os"
+)
+
+const (
+	Width  = 800
+	Height = 600
+)
+
+var img *image.RGBA
+
+func InitCanvas() {
+	img = image.NewRGBA(image.Rect(0, 0, Width, Height))
+	white := color.RGBA{255, 255, 255, 255}
+	for y := 0; y < Height; y++ {
+		for x := 0; x < Width; x++ {
+			img.Set(x, y, white)
+		}
+	}
+}
+
+func DrawPixel(x, y int) {
+	if img == nil {
+		return
+	}
+	if x < 0 || x >= Width || y < 0 || y >= Height {
+		return
+	}
+	img.Set(x, y, color.Black)
+}
+
+func SavePNG(filename string) error {
+	if img == nil {
+		return nil
+	}
+	f, err := os.Create(filename)
+	if err != nil {
+		return err
+	}
+	defer f.Close()
+	return png.Encode(f, img)
+}
diff --git a/semantices/semantices.go b/semantices/semantices.go
deleted file mode 100644
index 9123ae2..0000000
--- a/semantices/semantices.go
+++ /dev/null
@@ -1 +0,0 @@
-package semantices
diff --git a/test.sfdl b/test.sfdl
index b114a27..6702f0f 100644
--- a/test.sfdl
+++ b/test.sfdl
@@ -1,6 +1,32 @@
-origin is (100, 300);
-rot is 0;
-scale is (1, 1);
 
--- 画一个简单的函数
-for t from 0 to 10 step 0.5 draw (t, t*t);
+-- Arrow
+-- color is (255,255,0);
+
+scale is (1, 1);
+-- size is 10;
+
+origin is (450, 450);
+rot is pi;
+for t from 0 to 400 step 1 draw( t, t );
+
+
+-- 心形曲线
+
+origin is (200, 200);
+rot is pi/2;
+-- size is 5;
+
+-- 圆润型
+-- color is blue;
+scale is (50, 50);
+for t from -pi to pi step pi/200 draw((2*cos(t) - cos(2*t)),  (2*sin(t)-sin(2*t))  );
+
+-- 尖锐型
+origin is (200+80, 200+80);
+-- color is red;
+rot is pi;
+scale is (8, 8);
+for t from 0 to 2*pi  step pi/200 draw( 
+            16*(sin(t)**3),  
+			13*cos(t) - 5*cos(2*t) - 2*cos(3*t)-cos(4*t)
+	  );