Use missile range and subloop (OpenDiablo2#311)

Turn on blending.  Calculate target using based on range and angle of hero to click.

d2common/math.go

@@ -77,6 +77,14 @@ func GetAngleBetween(p1X, p1Y, p2X, p2Y float64) int {
 	return iResult
 }
 
+// GetRadiansBetween returns the radians between two points. 0rad is facing to the right.
+func GetRadiansBetween(p1X, p1Y, p2X, p2Y float64) float64 {
+	deltaY := p2Y - p1Y
+	deltaX := p2X - p1X
+
+	return math.Atan2(deltaY, deltaX)
+}
+
 // AlmostEqual returns true if two values are within threshold from each other
 func AlmostEqual(a, b, threshold float64) bool {
 	return math.Abs(a-b) <= threshold

d2core/d2asset/animation.go

@@ -44,9 +44,12 @@ type Animation struct {
 	compositeMode d2render.CompositeMode
 	colorMod      color.Color
 
-	playMode   playMode
-	playLength float64
-	playLoop   bool
+	playMode         playMode
+	playLength       float64
+	playLoop         bool
+	hasSubLoop       bool // runs after first animation ends
+	subStartingFrame int
+	subEndingFrame   int
 }
 
 func createAnimationFromDCC(dcc *d2dcc.DCC, palette *d2datadict.PaletteRec, transparency int) (*Animation, error) {
@@ -150,6 +153,12 @@ func (a *Animation) Clone() *Animation {
 	return &animation
 }
 
+func (a *Animation) SetSubLoop(startFrame, EndFrame int) {
+	a.subStartingFrame = startFrame
+	a.subEndingFrame = EndFrame
+	a.hasSubLoop = true
+}
+
 func (a *Animation) Advance(elapsed float64) error {
 	if a.playMode == playModePause {
 		return nil
@@ -162,26 +171,33 @@ func (a *Animation) Advance(elapsed float64) error {
 	a.lastFrameTime -= float64(framesAdvanced) * frameLength
 
 	for i := 0; i < framesAdvanced; i++ {
+		startIndex := 0
+		endIndex := frameCount
+		if a.hasSubLoop && a.playedCount > 0 {
+			startIndex = a.subStartingFrame
+			endIndex = a.subEndingFrame
+		}
+
 		switch a.playMode {
 		case playModeForward:
 			a.frameIndex++
-			if a.frameIndex >= frameCount {
+			if a.frameIndex >= endIndex {
 				a.playedCount++
 				if a.playLoop {
-					a.frameIndex = 0
+					a.frameIndex = startIndex
 				} else {
-					a.frameIndex = frameCount - 1
+					a.frameIndex = endIndex - 1
 					break
 				}
 			}
 		case playModeBackward:
 			a.frameIndex--
-			if a.frameIndex < 0 {
+			if a.frameIndex < startIndex {
 				a.playedCount++
 				if a.playLoop {
-					a.frameIndex = frameCount - 1
+					a.frameIndex = endIndex - 1
 				} else {
-					a.frameIndex = 0
+					a.frameIndex = startIndex
 					break
 				}
 			}

d2core/d2map/missile.go

@@ -5,11 +5,12 @@ import (
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2data/d2datadict"
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2resource"
 	"github.com/OpenDiablo2/OpenDiablo2/d2core/d2asset"
+	"math"
 )
 
 type Missile struct {
 	*AnimatedEntity
-	record         *d2datadict.MissileRecord
+	record *d2datadict.MissileRecord
 }
 
 func CreateMissile(x, y int, record *d2datadict.MissileRecord) (*Missile, error) {
@@ -21,6 +22,13 @@ func CreateMissile(x, y int, record *d2datadict.MissileRecord) (*Missile, error)
 		return nil, err
 	}
 
+	if record.Animation.HasSubLoop {
+		animation.SetSubLoop(record.Animation.SubStartingFrame, record.Animation.SubEndingFrame)
+	}
+
+	animation.SetBlend(true)
+	//animation.SetPlaySpeed(float64(record.Animation.AnimationSpeed))
+	animation.SetPlayLoop(record.Animation.LoopAnimation)
 	animation.PlayForward()
 	entity := CreateAnimatedEntity(x, y, animation)
 
@@ -32,6 +40,15 @@ func CreateMissile(x, y int, record *d2datadict.MissileRecord) (*Missile, error)
 	return result, nil
 }
 
+func (m *Missile) SetRadians(angle float64, done func()) {
+	r := float64(m.record.Range)
+
+	x := m.LocationX + (r * math.Cos(angle))
+	y := m.LocationY + (r * math.Sin(angle))
+
+	m.SetTarget(x, y, done)
+}
+
 func (m *Missile) Advance(tickTime float64) {
 	// TODO: collision detection
 	m.Step(tickTime)

d2game/d2player/game_controls.go

@@ -1,6 +1,7 @@
 package d2player
 
 import (
+	"github.com/OpenDiablo2/OpenDiablo2/d2common"
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2data/d2datadict"
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2enum"
 	"github.com/OpenDiablo2/OpenDiablo2/d2common/d2resource"
@@ -90,7 +91,13 @@ func (g *GameControls) OnMouseButtonDown(event d2input.MouseEvent) bool {
 			return false
 		}
 
-		missile.SetTarget(px*5, py*5, func() {
+		rads := d2common.GetRadiansBetween(
+			g.hero.AnimatedComposite.LocationX,
+			g.hero.AnimatedComposite.LocationY,
+			px*5,
+			py*5,
+		)
+		missile.SetRadians(rads, func() {
 			g.mapEngine.RemoveEntity(missile)
 		})