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unit Utils;
{***********************************************************
Project: C-evo External Map Generator
Copyright: 1999-2023 P Blackman
License: GPLv3+
General subroutines that don't belong anywhere else
***********************************************************}
interface
// Returns a value dependent on X, ranging from A to B,
// scaled to be bewteen 0 and 1
function JumpStep(A, B, X: Double): Double;
// fast Bias & gain functions
// scaled to work on input byte values with a percentage control
function Bias(TB, A: Integer): Integer;
function Gain(TB, A: Integer): Integer;
// Round to an integer with a probability of rounding up or down
// that is dependent on how near the value is to the upper or lower bound
function BlendRound(X: Double): Integer;
// Round small numbers up, others down, so 0.1 etc shows as non zero
function MyRound(S: Double): Integer;
// Combine gain & bias
function GainBias(val, G, B: Integer): Integer;
implementation
function MyRound(S: Double): Integer;
begin
if (S < 1) AND (S > 0.00001) then
// Round very small values up to 1
Result := 1
else
if S > 3 then
Result := Trunc(S)
else
Result := Round(S);
end;
function BlendRound(X: Double): Integer;
var Base: Integer;
Test: Double;
begin
// Offset so 0 is a full band
if X > 3.5 then
Result := 3
else
begin
X := X - 0.5;
Base := Trunc(X);
Test := 0.5; //Random;
if frac(X) > test then
Inc(base);
Result := base;
end;
end;
function JumpStep(A, B, X: Double): Double;
begin
if X < A then
Result := 0
else
if X >= B then
Result := 1
else
Result := (X - A) / (B - A);
end;
function Bias(TB, A: Integer): Integer;
var T: Double;
begin
if A <= 0 then
Result := 0
else
if A >= 100 then
Result := High(Byte)
else
begin
T := TB / High(Byte);
Result := Round(High(Byte) * T / ((100 / A - 2) * (1 - T) + 1));
end;
end;
function Gain(TB, A: Integer): Integer;
var T: Double;
begin
T := TB / High(Byte);
A := 100 - A; // Function seems to invert expected results
if A >= 100 then
Result := High(Byte) DIV 2 // 50%
else
if T < 0.5 then
if A <= 0 then
Result := 0
else
Result := Round(High(Byte) * T / ((100 / A - 2) * (1 - 2 * T) + 1))
else
if A <= 0 then
Result := High(Byte)
else
Result := Round(High(Byte) *
((100 / A - 2) * (1 - 2 * T) - T) / ((100 / A - 2) * (1 - 2 * T) - 1));
end;
function GainBias(val, G, B: Integer): Integer;
var temp1,
temp2,
Temp3: Integer;
begin
temp1 := val;
temp2 := Utils.Gain(temp1, G);
temp3 := Utils.Bias(temp2, B);
Result := temp3;
end;
end.
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