Working field maths and collision

1 files changed, 71 insertions, 3 deletions

diff --git a/tris/core.go b/tris/core.go
index 07b4b64..3121adf 100644
--- a/tris/core.go
+++ b/tris/core.go
@@ -35,26 +35,94 @@ type Placement struct {
 	Lock  int
 }
 
+func (p *Placement) Drop(f Field) bool {
+	newp := p
+	newp.Y++
+	if !newp.Collide(f) {
+		p = newp
+		return true
+	}
+	return false
+}
+
+func (p Placement) Collide(f Field) bool {
+	pf, ok := p.Field()
+	for x := 0; x < 9; x++ {
+		for y := 0; y < 19; y++ {
+			if f[y][x] && pf[y][x] {
+				return false
+			}
+		}
+	}
+	return ok
+}
+
+func (p Placement) Field() (Field, bool) {
+	var f Field
+	ok := true
+	for _, point := range p.Points() {
+		if point.X < 0 || point.X > 9 || point.Y > 19 {
+			ok = false
+			continue
+		}
+		if point.Y < 0 { // above the playing field we count the piece as on the board
+			continue
+		}
+		f[point.Y][point.X] = true
+	}
+	return f, ok
+}
+
+func (p Placement) Points() []Point {
+	piece := p.piece[p.Rot]
+	var points []Point
+	x := []int{0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3, 0, 1, 2, 3}
+	y := []int{0, 0, 0, 0, 1, 1, 1, 1, 2, 2, 2, 2, 3, 3, 3, 3}
+	for bm, i := uint16(0x8000), 0; i < 16; bm, i = bm >> 1, i + 1 {
+		if piece&bm == bm {
+			points = append(points, Point{X: p.X + x[i], Y: p.Y + y[i]})
+		}
+	}
+	return points
+}
+
 type Bag []Piece
 
 var LockDelay = 30
 
 var ReferenceBag = Bag{IPiece, JPiece, LPiece, OPiece, SPiece, TPiece, ZPiece}
 
+func NewBag() *Bag {
+	b := ReferenceBag.Randomize()
+	return &b
+}
+
 func (b Bag) Randomize() Bag { //TODO: implement randomizer
 	return b
 }
 
 func (b *Bag) Pick() Placement {
 	if len(*b) == 0 {
-		b = &ReferenceBag.Randomize()
+		b = NewBag()
 	}
-	piece := Placement{piece: Bag[0], X: 3, Y: -2, Lock: LockDelay}
-	*b = *b[1:]
+	piece := Placement{piece: (*b)[0], X: 3, Y: -2, Lock: LockDelay}
+	*b = (*b)[1:]
+	return piece
 }
 
 type Field [20][10]bool
 
+func (f Field) Add(p Placement) Field {
+	fn := f
+	for _, point := range p.Points() {
+		if point.Y < 0 || point.Y > 19 || point.X < 0 || point.X > 9 {
+			continue
+		}
+		fn[point.Y][point.X] = true
+	}
+	return fn
+}
+
 func (f Field) String() (output string) {
 	var toprow [10]bool
 	var top bool