+cRender():setTargetFPS(uint) to set target Framerate

if set >1 render sleeps until target frametime is reached

2 files changed, 89 insertions, 5 deletions

diff --git a/src/cRender.cpp b/src/cRender.cpp
index 57b06a7..71c4d76 100644
--- a/src/cRender.cpp
+++ b/src/cRender.cpp
@@ -11,6 +11,10 @@ cRender::cRender(char _backound, WORD _color, unsigned int _sx, unsigned int _sy
 	cBackound = _backound;
 	wBackColor = _color;
 
+	uTargetFPS = 0;
+	lastFrameTime = 0;
+	lastRenderTime = 0;
+
 #ifdef __linux__ //In Linux, setting Console size is not supported, so it gets Size of Console (Window) instead.
 
 	wDefColor = _COL_DEFAULT;
@@ -188,9 +192,16 @@ int cRender::render(void)
 	if (bBlockRender)
 		return _ERR_RENDER_BLOCKED_BY_CHILD_;
 
+	waitForFrametime();
+
 	//Resize screenbuffer if needed
 	setBufferSize( getConsoleWindowSize( ) );
 
+	printDebugInfo();
+
+	//For measuring render time
+	clock_t startTime = clock();
+
 	for (unsigned int i = 0; i < sizeY; i++) {
 		for (unsigned int o = 0; o < sizeX; o++) {
 			if(bChanged[o][i])
@@ -236,6 +247,18 @@ int cRender::render(void)
 			bChanged[o][i] = false;
 		}
 	}
+
+	//calc render time
+	lastRenderTime = clock() - startTime;
+
+	//calc time since last render
+	timespec now;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	lastFrameTime = (now.tv_sec - lastRender.tv_sec);
+	lastFrameTime += (now.tv_nsec - lastRender.tv_nsec) / 1000000000.0;
+	//save current time
+	clock_gettime(CLOCK_MONOTONIC, &lastRender);
+
 	return 0;
 }
 
@@ -417,3 +440,44 @@ void cRender::setConsoleEcho(bool _enable)
 		_enable ? write (STDOUT_FILENO, "\e[?8h", 5) : write (STDOUT_FILENO, "\e[?8l", 5);
 #endif //__linux__
 }
+
+double cRender::getFrametime()
+{
+	return lastFrameTime;
+}
+
+void cRender::setTargetFPS(unsigned int _fps)
+{
+	uTargetFPS = _fps;
+}
+
+void cRender::printDebugInfo()
+{
+	char dbgtxt[30];
+
+	sprintf(dbgtxt, "R: %f F: %f", ((float)lastRenderTime) / CLOCKS_PER_SEC, 1/getFrametime());
+
+	drawText(dbgtxt, {0,0}, _COL_BLACK | _COL_WHITE_BG);
+}
+
+void cRender::waitForFrametime()
+{
+	if(!uTargetFPS)
+		return;
+
+	timespec now;
+	double elapsed;
+	double left;
+	clock_gettime(CLOCK_MONOTONIC, &now);
+	elapsed = (now.tv_sec - lastRender.tv_sec);
+	elapsed += (now.tv_nsec - lastRender.tv_nsec) / 1000000000.0;
+
+	if(elapsed > (1/(double)uTargetFPS))
+		return;
+
+	left = (1/(double)uTargetFPS) - elapsed - (((double)lastRenderTime) / CLOCKS_PER_SEC);
+
+	std::this_thread::sleep_for(std::chrono::milliseconds(int (left * 1000)));
+
+
+}
diff --git a/src/cRender.h b/src/cRender.h
index 42c3388..19a0367 100644
--- a/src/cRender.h
+++ b/src/cRender.h
@@ -5,6 +5,9 @@
 #include <string>
 #include <cmath>
 #include <termios.h>
+#include <time.h> //clock()
+#include <chrono>
+#include <thread>
 
 #ifdef __linux__
 	#include <unistd.h>
@@ -131,6 +134,14 @@ public:
 	*/
 	sPos getSize();
 
+	/** Time in (real) seconds between last and second to last renders
+	*/
+	double getFrametime();
+
+	/** Sets target Framerate. 0 for unlimited
+	*/
+	void setTargetFPS(unsigned int _fps);
+
 
 protected:
 	/** Empty Constructor for being inheritable
@@ -159,6 +170,12 @@ protected:
 	unsigned int sizeX, sizeY;
 	//* Size of screen array
 
+	//Timekeeping
+	unsigned int uTargetFPS;
+	clock_t lastRenderTime;
+	double lastFrameTime;
+	timespec lastRender;
+
 #ifdef _WIN32
 	HANDLE hstdout;
 	CONSOLE_SCREEN_BUFFER_INFO csbi;
@@ -170,17 +187,20 @@ protected:
 	int iLastError;
 
 private:
+	void forceReRender();
+
+	void setConsoleEcho(bool _enable);
+
+	void printDebugInfo();
+
+	void waitForFrametime();
 #ifdef _WIN32
 	int SetConsoleWindowSize(int x, int y);
 	//Slightly adapted from: http://www.cplusplus.com/forum/windows/121444/
 
 	void gotoxy( int x, int y );
-#endif
-
-	void forceReRender();
 
-	void setConsoleEcho(bool _enable);
-#ifdef __linux__
+#elif __linux__
 	sPos getConsoleWindowSize();
 
 	void setConsoleCursor(bool _enable);