From 7932f4cc00fc9323793bc14c56658e420ce7ff71 Mon Sep 17 00:00:00 2001
From: Nathan Fulton <nathanfulton104@gmail.com>
Date: Sat, 29 Apr 2017 22:36:41 -0400
Subject: [PATCH] Implement FPS cap

---
 game/event.cpp | 57 ++++++++++++++++++++++++++++++++++++++++++++++++--
 game/game.cpp  |  1 +
 game/ht.h      | 11 ++++++----
 3 files changed, 63 insertions(+), 6 deletions(-)

diff --git a/game/event.cpp b/game/event.cpp
index dc30665..aea8b41 100644
--- a/game/event.cpp
+++ b/game/event.cpp
@@ -3,6 +3,7 @@
 namespace wi {
 
 EventMgr gevm;
+long gcmsNextPaint = 0;
 
 EventMgr::EventMgr()
 {
@@ -139,6 +140,24 @@ bool EventMgr::GetEvent(Event *pevt, long ctWait, bool fCheckPaints)
 #else
             {
 #endif
+                // Ensure that the skipped paint will be painted before sleeping kctForever
+
+                if ((m_wfRedraw & kfRedrawPaintSkipped) && ctWait == -1) {
+
+                    // Convert next paint to ticks
+
+                    long ctNextPaint = (gcmsNextPaint / 10);
+
+                    // Adjust wait time to next possible paint
+
+                    tCurrent = gtimm.GetTickCount();
+                    ctElapsed = tCurrent - tStart;
+                    ctWait = ctElapsed + ctNextPaint;
+
+                    m_wfRedraw &= ~kfRedrawPaintSkipped;
+                    m_wfRedraw |= kfRedrawDirty;
+                }
+
                 // Get the event from the host. The host doesn't coalesce
                 // messages, but does mark messages has being coalesce
                 // candidates, based on what was in the queue when the post
@@ -258,8 +277,16 @@ bool EventMgr::GetEvent(Event *pevt, long ctWait, bool fCheckPaints)
 			} else {
 				m_wfRedraw &= ~(kfRedrawDirty | kfRedrawBeforeTimer | kfRedrawBeforeInput);
 			}
-			pevt->eType = gamePaintEvent;
-			return true;
+
+            // Is it within the max fps rate?
+
+            if (CheckPaintFPS()) {
+                m_wfRedraw &= ~kfRedrawPaintSkipped;
+                pevt->eType = gamePaintEvent;
+                return true;
+            } else {
+                m_wfRedraw |= kfRedrawPaintSkipped;
+            }
 		}
 
 		// If the user timeout expired, return timeout
@@ -388,6 +415,32 @@ bool EventMgr::QueryPenHistory(int nPen, long ms, Point *ppt)
     
     return true;
 }
+
+bool EventMgr::CheckPaintFPS()
+{
+    long cmsCurrent = HostGetMillisecondCount();
+
+    // First time through?
+
+    if (gcmsNextPaint == 0) {
+        gcmsNextPaint = cmsCurrent + gcmsDisplayUpdate;
+        return true;
+    } else if (cmsCurrent >= gcmsNextPaint) {
+
+        // Is cmsCurrent is way ahead? This can occur after sleeping
+
+        if (cmsCurrent >= gcmsNextPaint + gcmsDisplayUpdate * 5) {
+            gcmsNextPaint = cmsCurrent + gcmsDisplayUpdate;
+        } else {
+            gcmsNextPaint += gcmsDisplayUpdate;
+        }
+        return true;
+    }
+
+    // There hasn't been enough time since the last draw
+
+    return false;
+}
     
 void EventMgr::Init()
 {
diff --git a/game/game.cpp b/game/game.cpp
index 2961a00..9969db1 100644
--- a/game/game.cpp
+++ b/game/game.cpp
@@ -71,6 +71,7 @@ bool gfMultiplayer;
 bool gfIgnoreBluetoothWarning;
 SpriteManager *gpsprm;
 TexAtlasMgr *gptam;
+int gcmsDisplayUpdate = 8; // mimimum ms to elapse between paints
 
 #ifdef STRESS
 bool gfStress = false;
diff --git a/game/ht.h b/game/ht.h
index 09fc47e..dbf2b32 100644
--- a/game/ht.h
+++ b/game/ht.h
@@ -1792,10 +1792,11 @@ enum {
 
 #define kcevtPostMax 20
 
-#define kfRedrawDirty 1
-#define kfRedrawMax 2
-#define kfRedrawBeforeTimer 4
-#define kfRedrawBeforeInput 8
+#define kfRedrawDirty 0x01
+#define kfRedrawMax 0x02
+#define kfRedrawBeforeTimer 0x04
+#define kfRedrawBeforeInput 0x08
+#define kfRedrawPaintSkipped 0x10
 
 struct FlickVector {
     int GetMagnitude() {
@@ -1848,6 +1849,7 @@ public:
 	}
 
 private:
+    bool CheckPaintFPS() secEventMgr;
     void UpdatePenHistory(Event *pevt) secEventMgr;    
     bool QueryPenHistory(int nPen, long t, Point *ppt);
 
@@ -8534,6 +8536,7 @@ extern int gnMPPos;
 extern char *gpszDataDir;
 extern bool gfIgnoreBluetoothWarning;
 extern TexAtlasMgr *gptam;
+extern int gcmsDisplayUpdate;
 
 inline Color GetColor(int iclr) {
 	return gaclrFixed[iclr];