feat: add line clear animation

game/grid.go

@@ -1,6 +1,8 @@
 package game
 
 import (
+	"slices"
+
 	"tetris/engine/graphics"
 )
 
@@ -44,6 +46,16 @@ func (g *Grid) ClearFullRows() byte {
 	return completed
 }
 
+func (g *Grid) FullRows() []byte {
+	rows := []byte{}
+	for y := byte(0); y < byte(g.Height()); y++ {
+		if g.IsRowFull(y) {
+			rows = append(rows, y)
+		}
+	}
+	return rows
+}
+
 func (g *Grid) IsRowFull(y byte) bool {
 	for x := range byte(g.Width()) {
 		if g.At(x, y) == BLOCK_EMPTY {
@@ -53,6 +65,17 @@ func (g *Grid) IsRowFull(y byte) bool {
 	return true
 }
 
+func (g *Grid) MoveRowsDown(rows ...byte) {
+	completed := byte(0)
+	for y := int(g.Height() - 1); y >= 0; y-- {
+		if slices.Contains(rows, byte(y)) {
+			completed++
+		} else if completed > 0 {
+			g.MoveRowDown(byte(y), completed)
+		}
+	}
+}
+
 func (g *Grid) MoveRowDown(y, num_rows byte) {
 	w := uint16(g.Width())
 	src := uint16(y) * w