Merge #3988

3988: improved the debug graphs. r=def- a=ChillerDragon

Closes https://github.com/teeworlds/teeworlds/issues/1058

(cherry picked from commit bf61d41c49)

No hard feelings from my side about the clamp. I am just hunting down em diffs to the upstream. But `@heinrich5991` seemed a bit concerned [back in 2013](https://github.com/teeworlds/teeworlds/issues/1058#issuecomment-12178577)

Old:
![screenshot_2021-08-04_10-12-54](https://user-images.githubusercontent.com/20344300/128148556-e818d45d-a455-4021-89a3-6f61cf187c93.png)


New:
![screenshot_2021-08-04_10-15-08](https://user-images.githubusercontent.com/20344300/128148516-b5a5fc79-2db8-4379-9d20-1a39c4d6285a.png)


## Checklist

- [X] Tested the change ingame
- [X] Provided screenshots if it is a visual change
- [ ] Tested in combination with possibly related configuration options
- [ ] Written a unit test if it works standalone, system.c especially
- [ ] Considered possible null pointers and out of bounds array indexing
- [X] Changed no physics that affect existing maps
- [ ] Tested the change with [ASan+UBSan or valgrind's memcheck](https://github.com/ddnet/ddnet/#using-addresssanitizer--undefinedbehavioursanitizer-or-valgrinds-memcheck) (optional)


Co-authored-by: oy <Tom_Adams@web.de>

src/engine/client/client.cpp

@@ -81,15 +81,15 @@ static const ColorRGBA ClientNetworkErrPrintColor{1.0f, 0.25f, 0.25f, 1.0f};
 
 void CGraph::Init(float Min, float Max)
 {
-	m_Min = Min;
-	m_Max = Max;
+	m_MinRange = m_Min = Min;
+	m_MaxRange = m_Max = Max;
 	m_Index = 0;
 }
 
 void CGraph::ScaleMax()
 {
 	int i = 0;
-	m_Max = 0;
+	m_Max = m_MaxRange;
 	for(i = 0; i < MAX_VALUES; i++)
 	{
 		if(m_aValues[i] > m_Max)
@@ -100,7 +100,7 @@ void CGraph::ScaleMax()
 void CGraph::ScaleMin()
 {
 	int i = 0;
-	m_Min = m_Max;
+	m_Min = m_MinRange;
 	for(i = 0; i < MAX_VALUES; i++)
 	{
 		if(m_aValues[i] < m_Min)
@@ -1089,7 +1089,11 @@ void CClient::DebugRender()
 		m_FpsGraph.ScaleMax();
 		m_FpsGraph.ScaleMin();
 		m_FpsGraph.Render(Graphics(), m_DebugFont, x, sp * 5, w, h, "FPS");
+		m_InputtimeMarginGraph.ScaleMin();
+		m_InputtimeMarginGraph.ScaleMax();
 		m_InputtimeMarginGraph.Render(Graphics(), m_DebugFont, x, sp * 5 + h + sp, w, h, "Prediction Margin");
+		m_GametimeMarginGraph.ScaleMin();
+		m_GametimeMarginGraph.ScaleMax();
 		m_GametimeMarginGraph.Render(Graphics(), m_DebugFont, x, sp * 5 + h + sp + h + sp, w, h, "Gametime Margin");
 	}
 }
@@ -3123,7 +3127,7 @@ void CClient::Run()
 	*/
 
 	//
-	m_FpsGraph.Init(0.0f, 200.0f);
+	m_FpsGraph.Init(0.0f, 120.0f);
 
 	// never start with the editor
 	g_Config.m_ClEditor = 0;

src/engine/client/client.h

@@ -41,6 +41,7 @@ public:
 	};
 
 	float m_Min, m_Max;
+	float m_MinRange, m_MaxRange;
 	float m_aValues[MAX_VALUES];
 	float m_aColors[MAX_VALUES][3];
 	int m_Index;