forked from Mirrors/openclonk
194 lines
4.4 KiB
C
194 lines
4.4 KiB
C
/*--
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Math.c
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Authors: Maikel, flgr, Newton, Tyron, Zapper
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Any kind of help with calculation.
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--*/
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// Returns the offset to x.
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global func AbsX(int x)
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{
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return x - GetX();
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}
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// Returns the offset to y.
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global func AbsY(int y)
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{
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return y - GetY();
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}
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// Supports negative values, and can deliver random values between two bounds.
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global func RandomX(int start, int end)
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{
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var swap;
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// Values swapped: reswap them.
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if (start > end)
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{
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swap = start;
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start = end;
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end = swap;
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}
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// Return random factor.
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return Random(end - start + 1) + start;
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}
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// Returns the sign of x.
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global func Sign(int x)
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{
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return (x>0)-(x<0);
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}
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// Tangens.
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global func Tan(int angle, int radius, int prec)
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{
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return radius * Sin(angle, radius * 100, prec) / Cos(angle, radius * 100, prec);
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}
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global func Normalize(int angle, int start, int precision)
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{
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if (!precision)
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precision = 1;
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var end = precision * 360 + start;
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while (angle < start)
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angle += precision * 360;
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while (angle >= end)
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angle -= precision * 360;
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return angle;
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}
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global func ComDirLike(int comdir1, int comdir2)
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{
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if (comdir1 == comdir2)
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return true;
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if (comdir1 == COMD_Stop || comdir2 == COMD_Stop)
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return false;
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if (comdir1 == COMD_None || comdir2 == COMD_None)
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return false;
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if (comdir1 % 8 + 1 == comdir2)
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return true;
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if (comdir1 == comdir2 % 8 + 1)
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return true;
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return false;
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}
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// the shortest direction (left/right) to turn from one angle to another
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// (for example for homing projectiles or aiming)
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global func GetTurnDirection(
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int from /* the angle at which the turning starts */
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, int to /* the angle that should be turned towards */)
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{
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/*
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// code for a homing missile
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var dir = GetTurnDirection(my_angle, target_angle);
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SetR(GetR() + dir / 10);
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SetSpeed(Sin(GetR(), 10), -Cos(GetR(), 10));
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*/
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var dir;
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/*if(to < from)*/dir=to-from;
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//else dir=from-to;
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var dif=360-from+to;
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var dif2=360-to+from;
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if(dif < 180)dir=+dif;
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else
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if(dif2 < 180)dir=-dif2;
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return dir;
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}
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global func SetBit(int old_val, int bit_nr, bool bit)
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{
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if (GetBit(old_val, bit_nr) != (bit != 0))
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return ToggleBit(old_val, bit_nr);
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return old_val;
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}
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global func GetBit(int value, int bit_nr)
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{
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return (value & (1 << bit_nr)) != 0;
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}
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global func ToggleBit(int old_val, int bit_nr)
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{
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return old_val ^ (1 << bit_nr);
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}
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// Returns -1 for DIR_Left and +1 for DIR_Right or 0 if no object context is present
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global func GetCalcDir()
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{
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if (!this) return 0;
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return GetDir() * 2 - 1;
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}
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//Moves param 'a' towards param 'b' by 'max' amount per frame
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global func MoveTowards(int a, int b, int max)
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{
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if(b == nil) return false;
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if(max == nil) max = 1;
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if(a < b) return BoundBy(a + max,a,b);
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if(a > b) return BoundBy(a - max,b,a);
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}
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global func FindHeight(int x)
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{
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var y = 0;
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while (!GBackSemiSolid(x, y) && y < LandscapeHeight())
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y += 10;
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while (GBackSemiSolid(x, y) && y)
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y--;
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return y;
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}
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/*
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Returns the normal vector of the (solid) landscape at a point relative to an object.
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Can f.e. be used to bounce projectiles.
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*/
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global func GetSurfaceVector(int x, int y)
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{
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var normal = [0, 0];
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var fac = 1;
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for(var fac = 1; fac <= 4; fac *= 2)
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{
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if(GBackSolid(x + fac, y)) --normal[0];
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if(GBackSolid(x - fac, y)) ++normal[0];
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if(GBackSolid(x, y + fac)) --normal[1];
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if(GBackSolid(x, y - fac)) ++normal[1];
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}
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return normal;
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}
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// Mathematical modulo operation for calculations in ℤ/nℤ.
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//
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// Examples:
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// (12 % 10) == Mod(12, 10) == 2
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// (-1 % 10) == -1
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// Mod(-1, 10) == 9
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global func Mod(int dividend, int divisor)
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{
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var a = dividend, b = divisor;
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return (a % b + b) % b;
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}
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// Returns whether the line from (x1, y1) to (x2, y2) overlaps with the line from (x3, y3) to (x4, y4).
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// Whenever the two lines share a starting or ending point they are not considered to be overlapping.
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global func IsLineOverlap(int x1, int y1, int x2, int y2, int x3, int y3, int x4, int y4)
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{
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// Same starting or ending point is not overlapping.
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if ((x1 == x3 && y1 == y3) || (x1 == x4 && y1 == y4) || (x2 == x3 && y2 == y3) || (x2 == x4 && y2 == y4))
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return false;
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// Check if line from (x1, y1) to (x2, y2) crosses the line from (x3, y3) to (x4, y4).
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var d1x = x2 - x1, d1y = y2 - y1, d2x = x4 - x3, d2y = y4 - y3, d3x = x3 - x1, d3y = y3 - y1;
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var a = d1y * d3x - d1x * d3y;
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var b = d2y * d3x - d2x * d3y;
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var c = d2y * d1x - d2x * d1y;
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if (!c)
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return !a && Inside(x3, x1, x2) && Inside(y3, y1, y2); // lines are parallel
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return a * c >= 0 && !(a * a / (c * c + 1)) && b * c >= 0 && !(b * b/(c * c + 1));
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}
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