KoroLion/FunctionImagingInPascal
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Feature: better graphing by using gradient

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KoroLion 2020-05-14 18:17:36 +03:00
parent 018f33ef55
commit 1f4577657e
1 changed files with 24 additions and 6 deletions
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30
src/function_imaging.pas
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@ -35,7 +35,7 @@ begin
args.width := strToInt(ParamStr(1));
args.height := strToInt(ParamStr(2));
args.f := ParamStr(3);
args.zoom := StrToFloat(ParamStr(4)) * 10;
args.zoom := StrToFloat(ParamStr(4));
args.centerX := StrToFloat(ParamStr(5));
args.centerY := StrToFloat(ParamStr(6));
@ -71,11 +71,13 @@ var
fParser: TFPExpressionParser;
argX, argY: TFPExprIdentifierDef;
x, y, intense: integer;
convX, convY, fRes: extended;
convX, convY, fRes1, fRes2, pixelRadius: extended;
dfDx, dfDy, delta, gradLen: extended;
ineq: boolean;
begin
setLength(pxData, args.width, args.height);
fParser := TFPExpressionParser.create(nil);
pixelRadius := 1 / args.zoom;
try
fParser.builtIns := [bcMath];
@ -88,7 +90,7 @@ begin
for y := 0 to args.height - 1 do begin
for x := 0 to args.width - 1 do begin
convX := ((x - args.width / 2) / args.zoom) + args.centerX;
convX := (x - args.width / 2) / args.zoom + args.centerX;
convY := -(y - args.height / 2) / args.zoom + args.centerY;
if (abs(convX) < (1 / args.zoom)) or (abs(convY) < (1 / args.zoom)) then begin
@ -104,12 +106,28 @@ begin
pxData[x][y].set_color(255, 255, 255);
end;
end else begin
fRes := fParser.evaluate().resFloat;
fRes1 := fParser.evaluate().resFloat;
if (abs(fRes) > (1 / args.zoom)) then begin
// finding derivative of a function at this point (numeric)
delta := 0.00001;
argX.asFloat := convX + delta;
argY.asFloat := convY;
fRes2 := fParser.evaluate().resFloat;
dfDx := (fRes2 - fRes1) / delta;
argX.asFloat := convX;
argY.asFloat := convY + delta;
fRes2 := fParser.evaluate().resFloat;
dfDy := (fRes2 - fRes1) / delta;
// calculating length of a gradient at this point
gradLen := sqrt(sqr(dfDx) + sqr(dfDy));
if (abs(fRes1) > (gradLen * pixelRadius)) then begin
pxData[x][y].set_color(255, 255, 255);
end else begin
intense := round(abs(fRes) / (1 / args.zoom));
intense := round(abs(fRes1) / (gradLen * pixelRadius));
pxData[x][y].set_color(intense, intense, intense);
end;
end;