From 02d5db007c54cd79f2a043a1b4cb39d0432ccbb9 Mon Sep 17 00:00:00 2001
From: =?utf8?q?Alexis=20Laferri=C3=A8re?= <alexis.laf@xymus.net>
Date: Thu, 22 Jun 2017 22:28:39 -0400
Subject: [PATCH] gamnit: cache sprite GPU index, as index_of is very costly
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Signed-off-by: Alexis Laferrière <alexis.laf@xymus.net>
---
 lib/gamnit/flat.nit |   47 ++++++++++++++++++++++++++++++++++++-----------
 1 file changed, 36 insertions(+), 11 deletions(-)

diff --git a/lib/gamnit/flat.nit b/lib/gamnit/flat.nit
index b278029..f9710ab 100644
--- a/lib/gamnit/flat.nit
+++ b/lib/gamnit/flat.nit
@@ -253,6 +253,9 @@ class Sprite
 	# Current context to which `self` was sorted
 	private var context: nullable SpriteContext = null
 
+	# Index in `context`
+	private var context_index: Int = -1
+
 	# Current context to which `self` belongs
 	private var sprite_set: nullable SpriteSet = null
 end
@@ -768,7 +771,7 @@ private class SpriteContext
 	var usage: GLBufferUsage
 
 	# Sprites drawn by this context
-	var sprites = new GroupedArray[Sprite]
+	var sprites = new GroupedSprites
 
 	# Sprites to update since last `draw`
 	var sprites_to_update = new Set[Sprite]
@@ -878,8 +881,11 @@ private class SpriteContext
 	# Update GPU data of `sprite`
 	fun update_sprite(sprite: Sprite)
 	do
-		var sprite_index = sprites.index_of(sprite)
-		if sprite_index == -1 then return
+		var context = sprite.context
+		if context != self then return
+
+		var sprite_index = sprite.context_index
+		assert sprite_index != -1
 
 		# Vertices data
 
@@ -1169,9 +1175,6 @@ private class GroupedArray[E]
 	# Number of item slots in the array
 	fun capacity: Int do return items.length
 
-	# Index of `item`
-	fun index_of(item: E): Int do return items.index_of(item)
-
 	# List of available slots
 	var available = new MinHeap[Int].default
 
@@ -1181,8 +1184,8 @@ private class GroupedArray[E]
 	# Index of the spots after filled chunks
 	var ends = new List[Int]
 
-	# Add `item` to the first available slot
-	fun add(item: E)
+	# Add `item` to the first available slot and return its index
+	fun add(item: E): Int
 	do
 		length += 1
 
@@ -1207,7 +1210,7 @@ private class GroupedArray[E]
 				# at end of first chunk
 				ends.first += 1
 			end
-			return
+			return i
 		end
 
 		items.add item
@@ -1215,13 +1218,20 @@ private class GroupedArray[E]
 			starts.add 0
 			ends.add 1
 		else ends.last += 1
+		return ends.last - 1
 	end
 
 	# Remove the first instance of `item`
 	fun remove(item: E)
 	do
-		var i = items.index_of(item)
-		assert i != -1
+		var index = items.index_of(item)
+		remove_at(item, index)
+	end
+
+	# Remove `item` at `index`
+	fun remove_at(item: E, index: Int)
+	do
+		var i = index
 		length -= 1
 		items[i] = null
 
@@ -1296,6 +1306,7 @@ private class GroupedArray[E]
 		while max > 0 and (starts.length > 1 or starts.first != 0) do
 			var i = ends.last - 1
 			var e = items[i]
+			assert e != null
 			remove e
 			add e
 			moved.add e
@@ -1328,6 +1339,20 @@ private class GroupedArray[E]
 	end
 end
 
+# Optimized `GroupedArray` to use `Sprite::context_index` and avoid using `index_of`
+private class GroupedSprites
+	super GroupedArray[Sprite]
+
+	redef fun add(item)
+	do
+		var index = super
+		item.context_index = index
+		return index
+	end
+
+	redef fun remove(item) do remove_at(item, item.context_index)
+end
+
 redef class GLfloatArray
 	private fun fill_from_matrix(matrix: Matrix, dst_offset: nullable Int)
 	do
-- 
1.7.9.5