up3

server/item/splash_potion.go

@@ -0,0 +1,49 @@
+package item
+
+import (
+	"github.com/df-mc/dragonfly/server/block/cube"
+	"github.com/df-mc/dragonfly/server/item/potion"
+	"github.com/df-mc/dragonfly/server/world"
+	"github.com/df-mc/dragonfly/server/world/sound"
+	"math"
+)
+
+// SplashPotion is an item that grants effects when thrown.
+type SplashPotion struct {
+	// Type is the type of splash potion.
+	Type potion.Potion
+}
+
+// MaxCount ...
+func (s SplashPotion) MaxCount() int {
+	return 1
+}
+
+// Use ...
+func (s SplashPotion) Use(tx *world.Tx, user User, ctx *UseContext) bool {
+	create := tx.World().EntityRegistry().Config().SplashPotion
+	opts := world.EntitySpawnOpts{Position: eyePosition(user), Velocity: throwableOffset(user.Rotation()).Vec3().Mul(0.5)}
+	tx.AddEntity(create(opts, s.Type, user))
+	tx.PlaySound(user.Position(), sound.ItemThrow{})
+
+	ctx.SubtractFromCount(1)
+	return true
+}
+
+// throwableOffset adds an upwards offset pitch to a throwable entity.
+// In vanilla, items such as Splash Potions, Lingering Potions, and
+// Bottle o' Enchanting are thrown at a higher angle than where the
+// player is looking at.
+// The added offset is an ellipse-like shape based on what the input pitch is.
+func throwableOffset(r cube.Rotation) cube.Rotation {
+	r[1] = max(min(r[1], 89.9), -89.9)
+	r[1] -= math.Sqrt(89.9*89.9-r[1]*r[1]) * (26.5 / 89.9)
+	r[1] = max(min(r[1], 89.9), -89.9)
+
+	return r
+}
+
+// EncodeItem ...
+func (s SplashPotion) EncodeItem() (name string, meta int16) {
+	return "minecraft:splash_potion", int16(s.Type.Uint8())
+}