53 lines
1.7 KiB
Go
53 lines
1.7 KiB
Go
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package enchantment
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import (
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"github.com/df-mc/dragonfly/server/item"
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"github.com/df-mc/dragonfly/server/world"
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"math"
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)
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// AffectedDamageSource represents a world.DamageSource whose damage may be
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// affected by an enchantment. A world.DamageSource does not need to implement
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// AffectedDamageSource to let protection affect the damage. This happens
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// depending on the (world.DamageSource).ReducedByResistance() method.
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type AffectedDamageSource interface {
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world.DamageSource
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// AffectedByEnchantment specifies if a world.DamageSource is affected by
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// the item.EnchantmentType passed.
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AffectedByEnchantment(e item.EnchantmentType) bool
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}
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// DamageModifier is an item.EnchantmentType that can reduce damage through a
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// modifier if an AffectedDamageSource returns true for it.
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type DamageModifier interface {
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Modifier() float64
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}
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// ProtectionFactor calculates the combined protection factor for a slice of
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// item.Enchantment. The factor depends on the world.DamageSource passed and is
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// in a range of [0, 0.8], where 0.8 means incoming damage would be reduced by
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// 80%.
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func ProtectionFactor(src world.DamageSource, enchantments []item.Enchantment) float64 {
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f := 0.0
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for _, e := range enchantments {
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t := e.Type()
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modifier, ok := t.(DamageModifier)
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if !ok {
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continue
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}
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reduced := false
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if _, ok := t.(protection); ok && src.ReducedByResistance() {
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// Special case for protection, because it applies to all damage
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// sources by default, except those not reduced by resistance.
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reduced = true
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} else if asrc, ok := src.(AffectedDamageSource); ok && asrc.AffectedByEnchantment(t) {
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reduced = true
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}
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if reduced {
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f += float64(e.Level()) * modifier.Modifier()
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}
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}
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return math.Min(f, 0.8)
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}
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