From e39104d8ea66ccc7a2919eb65bf5b46d187297f8 Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Miloslav=20=C4=8C=C3=AD=C5=BE?= <tastyfish@seznam.cz>
Date: Tue, 11 Sep 2018 10:33:47 +0200
Subject: [PATCH] Optimize sprites

---
 demo3.cpp   |  5 +++--
 general.hpp | 12 ++++++++++--
 2 files changed, 13 insertions(+), 4 deletions(-)

diff --git a/demo3.cpp b/demo3.cpp
index 4469723..94b0609 100644
--- a/demo3.cpp
+++ b/demo3.cpp
@@ -11,6 +11,7 @@
 */
 
 // redefine player's height
+#define PLAYER_SPEED (UNITS_PER_SQUARE * 7)
 #define CAMERA_COLL_HEIGHT_BELOW ((3 * UNITS_PER_SQUARE) / 2)
 #define FPS 40
 #define HEAD_BOB_HEIGHT 150
@@ -270,7 +271,7 @@ void cameraFlyBy(uint32_t dt)
 
   Unit heightDiff = player.mCamera.height - height;
 
-  Unit step = (100 * dt) / 1000;
+  Unit step = (200 * dt) / 1000;
 
   if (heightDiff > UNITS_PER_SQUARE * 2)
   {
@@ -289,7 +290,7 @@ void cameraFlyBy(uint32_t dt)
   player.mCamera.position.x += step * 30;
   player.mCamera.position.y += step * 15;
 
-  player.mCamera.direction = sinInt(pokitto.frameCount / 4);
+  player.mCamera.direction = sinInt(pokitto.frameCount / 8);
 }
 
 int main()
diff --git a/general.hpp b/general.hpp
index b470ff7..f07a0d5 100644
--- a/general.hpp
+++ b/general.hpp
@@ -163,7 +163,15 @@ inline uint8_t sampleImage(const unsigned char *image, Unit x, Unit y)
 
 void inline drawSprite(const unsigned char *sprite, int16_t x, int16_t y, Unit depth, int16_t size)
 {
-  // TODO: optimize
+  if (size < 0 || size > 200) // let's not mess up with the incoming array
+    return;
+
+  int16_t samplingIndices[size];
+
+  // optimization: precompute the indices
+
+  for (Unit i = 0; i < size; ++i)
+    samplingIndices[i] = (i * UNITS_PER_SQUARE) / size;
 
   x -= size / 2;
   y -= size / 2;
@@ -184,7 +192,7 @@ void inline drawSprite(const unsigned char *sprite, int16_t x, int16_t y, Unit d
 
     for (Unit j = max(-1 * y,0); j < jTo; ++j)
     {
-      c = sampleImage(sprite,(i * UNITS_PER_SQUARE) / size,(j * UNITS_PER_SQUARE) / size); 
+      c = sampleImage(sprite,samplingIndices[i],samplingIndices[j]); 
      
       if (c != TRANSPARENT_COLOR)
         pokitto.display.drawPixel(xPos,y + j,c);