From d4bb64d6f944713b46eabe7bbbed489ba8619acb Mon Sep 17 00:00:00 2001
From: outfrost <kotlet.bahn@gmail.com>
Date: Sun, 6 Jan 2019 06:25:55 +0100
Subject: [PATCH] Add frametime & fps metering

It runs at 2400 fps. My PC might need help later.
---
 Makefile      |  5 ++++-
 main.c        |  2 ++
 performance.c | 42 ++++++++++++++++++++++++++++++++++++++++++
 performance.h |  7 +++++++
 render.c      |  3 +++
 5 files changed, 58 insertions(+), 1 deletion(-)
 create mode 100644 performance.c
 create mode 100644 performance.h

diff --git a/Makefile b/Makefile
index a296fac..0490851 100644
--- a/Makefile
+++ b/Makefile
@@ -4,7 +4,7 @@ libraries ::= -L/usr/local/lib -lGL -lglut -lassimp
 # Prefix all object file names with the compilation directory
 objects ::= $(addprefix out/, \
               main.o debugutil.o glut_janitor.o render.o \
-              tga.o level.o)
+              tga.o level.o performance.o)
 
 # Set executable extension for the platform
 ifeq ($(OS),Windows_NT)
@@ -56,3 +56,6 @@ out/tga.o : tga.c tga.h | out
 
 out/level.o : level.c level.h tga.h | out
 	$(CC) $(compileargs) -c -o out/level.o level.c
+
+out/performance.o : performance.c | out
+	$(CC) $(compileargs) -c -o out/performance.o performance.c
diff --git a/main.c b/main.c
index 22e6831..34d7ec6 100644
--- a/main.c
+++ b/main.c
@@ -4,6 +4,7 @@
 #include "glut_janitor.h"
 #include "render.h"
 #include "level.h"
+#include "performance.h"
 
 int main(int argc, char** argv) {
 	glutInit(&argc, argv);
@@ -22,6 +23,7 @@ int main(int argc, char** argv) {
 	//glutMotionFunc(mouse_motion_event);
 	
 	initRender();
+	initPerformanceMetering();
 	
 	model = importModel("out/assets/wall01.3ds");
 	/*
diff --git a/performance.c b/performance.c
new file mode 100644
index 0000000..cb3709f
--- /dev/null
+++ b/performance.c
@@ -0,0 +1,42 @@
+#include <time.h>
+#include <stdio.h> // TODO remove
+#include <stdbool.h>
+
+typedef struct timespec Timepoint;
+
+static Timepoint lastDisplayTime;
+static int frames = 0;
+static bool meteringEnabled = false;
+
+void initPerformanceMetering() {
+	if (clock_gettime(CLOCK_MONOTONIC, &lastDisplayTime) != 0) {
+		fprintf(stderr, "Clock read failed, performance metering unavailable\n");
+	}
+	else {
+		meteringEnabled = true;
+	}
+}
+
+void frameRendered() {
+	if (meteringEnabled) {
+		++frames;
+		Timepoint now;
+		
+		if (clock_gettime(CLOCK_MONOTONIC, &now) != 0) {
+			fprintf(stderr, "Clock read failed, stopping performance metering\n");
+			meteringEnabled = false;
+			return;
+		}
+		
+		time_t fullSeconds = now.tv_sec - lastDisplayTime.tv_sec;
+		if (now.tv_nsec < lastDisplayTime.tv_nsec) --fullSeconds;
+		
+		if (fullSeconds > 0) {
+			float seconds = (now.tv_nsec - lastDisplayTime.tv_nsec) / 1000000000.0f;
+			seconds += (float) (now.tv_sec - lastDisplayTime.tv_sec);
+			printf("frametime avg %.1f ms; fps avg %.f\n", (seconds / frames) * 1000.0f, (frames / seconds));
+			lastDisplayTime = now;
+			frames = 0;
+		}
+	}
+}
diff --git a/performance.h b/performance.h
new file mode 100644
index 0000000..b4ded6b
--- /dev/null
+++ b/performance.h
@@ -0,0 +1,7 @@
+#ifndef PERFORMANCE_H_
+#define PERFORMANCE_H_
+
+void initPerformanceMetering();
+void frameRendered();
+
+#endif
diff --git a/render.c b/render.c
index 3e29339..a1f5a30 100644
--- a/render.c
+++ b/render.c
@@ -3,6 +3,7 @@
 
 #include "render.h"
 #include "typedefs.h"
+#include "performance.h"
 
 const float AXIS_RADIUS = 5.0f;
 
@@ -15,6 +16,8 @@ void renderScene() {
 	
 	glFlush();
 	glutSwapBuffers();
+	frameRendered();
+	glutPostRedisplay();
 }
 
 void drawAxes() {
-- 
2.44.0