Trendline Indicator

Kind Greetings,

I have been trying to code an AFL indicator that will render a trendline that will be used as a support-resistance reference line.
The trendline would be drawn through yesterdays 9:30AM candle (open+close)/2 and yesterdays 4:00PM candle (open+close)/2 and extend into today.
I have found an automatic trendline formula in the AFL library and have been trying to modify it by removing the trough function references which has worked but I'm having trouble trying to get the trendline to go through the specific times.
I'm not sure which function reference to use to give me the desired time points. I can get a trendline to plot but it only works if I use constants for the start and end values.
Any help on this would be greatly appreciated.

Thank you,
All the best

convertah


x = Cum(1);

perchg = 0.3*LastValue( Highest( ROC( Low, 50 ) ));

startvalue = LastValue( Trough( Low, perchg, 1 ) );
endvalue1 = LastValue( Trough( Low, perchg, 2 ) );

startbar = LastValue( ValueWhen( Low == startvalue, x, 1 ) );
endbar = LastValue( ValueWhen( Low == endvalue1, x, 1 ) );

Aa = (endvalue1-startvalue)/(endbar-startbar);
b = startvalue;

trendline = Aa * ( x - startbar ) + b;

Plot( Close, "Price", colorBlue, styleCandle );
Plot( IIf( x >= endbar, trendline, Null ), "Trendline", colorRed );

Pls find herewith afl for Advanced Trendlines which i got from Amibroker fan.


_SECTION_BEGIN("Advanced Trend Lines");
function TD_Supply()
{
return ( H > Ref(H, 1) AND H > Ref(H, -1) AND H > Ref(C, -2));
}
function TD_Demand()
{
return ( L < Ref(L, 1) AND L < Ref(L, -1) AND L < Ref(C, -2));
}

function IsTD_Supply(n)
{
n = (BarCount - 1) - n;
return LastValue( Ref(H, -n) > Ref(H, -n+1) AND Ref(H, -n) > Ref(H, -n-1) AND Ref(H, -n) > Ref(C, -n-2));
}
function IsTD_Demand(n)
{
n = (BarCount - 1) - n;
return LastValue( Ref(L, -n) < Ref(L, -n+1) AND Ref(L, -n) < Ref(L, -n-1) AND Ref(L, -n) < Ref(C, -n-2));
}
function GetXSupport(Lo, Percentage, Back)
{
return ((BarCount - 1) - LastValue(TroughBars(Lo, Percentage,Back)));
}
function GetYSupport(Lo, Percentage, Back)
{
return (LastValue(Trough(Lo, Percentage, back)));
}

function GetXResistance(Hi, Percentage, Back)
{
return ((BarCount - 1) -LastValue(PeakBars(Hi, Percentage, Back)));
}
function GetYResistance(Hi, Percentage, Back)
{
return (LastValue(Peak(Hi, Percentage, Back)));
}
////////////////////////////////////////////////////////////////////////
//Parameters
Percentage = Param("Percentage", 0.5, 0.01, 100. ,0.01);
Lines = Param("Lines?", 5, 1, BarCount-2);
DrawR = ParamList("Resistance Points", "Off|High to High|High to Low", 1);
DrawS = ParamList("Support Points", "Off|Low to Low|Low to High", 1);
DrawAllLines = ParamToggle("Draw All Lines?", "No|Yes", 1);
Method = ParamToggle("Method", "TD Points|ZigZag",1);
ShowTDP = ParamToggle("Show TD Pionts", "No|Yes");
AllOrDownR = ParamToggle("Resistance Direction", "All|Down");
AllOrUpS = ParamToggle("Support Direction", "All|Up");
////////////////////////////////////////////////////////////////////////
Main = C;
Con = ConS = ConR = 1;
if(DrawS=="Low to Low")
{
Support1 = L;
Support2 = L;
}
else
{
Support1 = L;
Support2 = H;
}
if(DrawR=="High to High")
{
Resistance1 = H;
Resistance2 = H;
}
else
{
Resistance1 = H;
Resistance2 = L;
}
////////////////////////////////////////////////////////////////////////
//Plotting Area
Plot(Main, "", IIf(C>O,colorGreen, colorRed), styleBar);
if(DrawAllLines)
for(i = 2; i<=Lines+1; i++)
{
if(DrawS!="Off")
{
x0 = GetXSupport(Support1, Percentage, i);
x1 = GetXSupport(Support2, Percentage, i-1);
y0 = GetYSupport(Support1, Percentage, i);
y1 = GetYSupport(Support2, Percentage, i-1);
x = LineArray(x0, y0, x1, y1, 1);
if(!Method)
Con = (IsTD_Demand(x0) AND IsTD_Demand(x1));
if(AllOrUpS) ConS = y0 < y1;
if(Con AND ConS)
Plot(x, "", colorLightBlue, styleLine|styleThick);
}
if(DrawR!="Off")
{
x0 = GetXResistance(Resistance1, Percentage, i);
x1 = GetXResistance(Resistance2, Percentage, i-1);
y0 = GetYResistance(Resistance1, Percentage, i);
y1 = GetYResistance(Resistance2, Percentage, i-1);
x = LineArray(x0, y0, x1, y1, 1);
if(!Method)
Con = (IsTD_Supply(x0) AND IsTD_Supply(x1));
if(AllOrDownR) ConR = y0 > y1;
if(Con AND ConR)
Plot(x, "", colorRed , styleLine|styleThick);
}
}
else
{
if(DrawS!="Off")
{
x0 = GetXSupport(Support1, Percentage, Lines+1);
x1 = GetXSupport(Support2, Percentage, Lines);
y0 = GetYSupport(Support1, Percentage, Lines+1);
y1 = GetYSupport(Support2, Percentage, Lines);
x = LineArray(x0, y0, x1, y1, 1);
if(!Method)
Con = (IsTD_Demand(x0) AND IsTD_Demand(x1));
if(AllOrUpS) ConS = y0 < y1;
if(Con AND ConS)
Plot(x, "", colorLightBlue, styleLine|styleThick);
}
if(DrawR!="Off")
{
x0 = GetXResistance(Resistance1, Percentage, Lines+1);
x1 = GetXResistance(Resistance2, Percentage, Lines);
y0 = GetYResistance(Resistance1, Percentage, Lines+1);
y1 = GetYResistance(Resistance2, Percentage, Lines);
x = LineArray(x0, y0, x1, y1, 1);
if(!Method)
Con = (IsTD_Supply(x0) AND IsTD_Supply(x1));
if(AllOrDownR) ConR = y0 > y1;
if(Con AND ConR)
Plot(x, "", colorRed , styleLine|styleThick);
}
}

if(ShowTDP)
{
PlotShapes(TD_Supply()*shapeSmallCircle, colorRed, 0, H, H*.001);
PlotShapes(TD_Demand()*shapeSmallCircle, colorGreen, 0, L, -L*.001);
}
Title =FullName()+" ({{NAME}})\n{{DATE}}\n"+"Open: "+O+", Hi: "+H+", Lo: "+L+", Close: "+C;

_SECTION_END();

raakesh,

Thanks for the code I will try it.
The current code which I have for the trendline through the beginning and ending candle of the day (open+close)/2 is:

x = Cum(1);

startvalue = LastValue(Ref( (O+C)/2, -157 ));
endvalue1 = LastValue(Ref( (O+C)/2, -79 ));

startbar = LastValue( ValueWhen( (O+C)/2 == startvalue, x, 1 ) );
endbar = LastValue( ValueWhen( (O+C)/2 == endvalue1, x, 1 ) );

Aa = (endvalue1-startvalue)/(endbar-startbar);
b = startvalue;

trendline = Aa * ( x - startbar ) + b;

Plot( Close, "Price", colorBlue, styleCandle );
Plot( trendline, "Trendline", colorRed );

All this code does is count back from the last 5 minute candle of today and only works if today is finished. This code needs to be refined and I will post more as I figure out what to do.
This simple trendline when coded correctly acts as a good support-resistance indicator for future price action.

Thank you,
convertah