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/* This file is part of the Spring engine (GPL v2 or later), see LICENSE.html */
// F(N=2) = H(-32768 / 32767)
//
// ^
// |
// |
// F(W=3) = H(-16384) <---o---> F(E=1) = H(16384)
// |
// |
// v
//
// F(S=0) = H(0)
inline short int GetHeadingFromFacing(const int facing)
{
switch (facing) {
case FACING_SOUTH: return 0;
case FACING_EAST: return 16384;
case FACING_NORTH: return 32767;
case FACING_WEST: return -16384;
default: return 0;
}
}
inline int GetFacingFromHeading(const short int heading)
{
if (heading >= 0) {
if (heading < 8192) { return FACING_SOUTH; }
if (heading < 24576) { return FACING_EAST; }
return FACING_NORTH;
} else {
if (heading >= -8192) { return FACING_SOUTH; }
if (heading >= -24576) { return FACING_WEST; }
return FACING_NORTH;
}
}
inline float GetHeadingFromVectorF(const float dx, const float dz)
{
float h = 0.0f;
if (dz != 0.0f) {
float d = dx / dz;
if (d > 1.0f) {
h = HALFPI - d / (d * d + 0.28f);
} else if (d < -1.0f) {
h = -HALFPI - d / (d * d + 0.28f);
} else {
h = d / (1.0f + 0.28f * d * d);
}
if (dz < 0.0f) {
if (dx > 0.0f)
h += PI;
else
h -= PI;
}
} else {
if (dx > 0.0f)
h = HALFPI;
else
h = -HALFPI;
}
return h;
}
inline short int GetHeadingFromVector(const float dx, const float dz)
{
float h = GetHeadingFromVectorF(dx, dz);
h *= SHORTINT_MAXVALUE * INVPI;
// Prevents h from going beyond SHORTINT_MAXVALUE.
// If h goes beyond SHORTINT_MAXVALUE, the following
// conversion to a short int crashes.
// if (h > SHORTINT_MAXVALUE) h = SHORTINT_MAXVALUE;
// return (short int) h;
int ih = (int) h;
if (ih == -SHORTINT_MAXVALUE) {
// ih now represents due-north, but the modulo operation
// below would cause it to wrap around from -32768 to 0
// which means due-south, so add 1
ih += 1;
}
ih %= SHORTINT_MAXVALUE;
return (short int) ih;
}
// vec should be normalized
inline shortint2 GetHAndPFromVector(const float3 vec)
{
shortint2 ret;
// Prevents ret.y from going beyond SHORTINT_MAXVALUE.
// If h goes beyond SHORTINT_MAXVALUE, the following
// conversion to a short int crashes.
// this change destroys the whole meaning with using short ints....
int iy = (int) (math::asin(vec.y) * (SHORTINT_MAXVALUE * INVPI));
iy %= SHORTINT_MAXVALUE;
ret.y = (short int) iy;
ret.x = GetHeadingFromVector(vec.x, vec.z);
return ret;
}
// vec should be normalized
inline float2 GetHAndPFromVectorF(const float3 vec)
{
float2 ret;
ret.x = GetHeadingFromVectorF(vec.x, vec.z);
ret.y = math::asin(vec.y);
return ret;
}
inline float3 GetVectorFromHeading(const short int heading)
{
const int idx = heading / ((SHORTINT_MAXVALUE/NUM_HEADINGS) * 2) + NUM_HEADINGS/2;
const float2 vec = CMyMath::headingToVectorTable[idx];
return float3(vec.x, 0.0f, vec.y);
}
inline float3 CalcBeizer(const float i, const float3 p1, const float3 p2, const float3 p3, const float3 p4)
{
const float ni = 1.0f - i;
const float a = ni * ni * ni;
const float b = 3.0f * i * ni * ni;
const float c = 3.0f * i * i * ni;
const float d = i * i * i;
return float3((p1 * a) + (p2 * b) + (p3 * c) + (p4 * d));
}
inline int Round(const float f)
{
return math::floor(f + 0.5f);
}
inline int2 IdxToCoord(unsigned x, unsigned array_width)
{
int2 r;
r.x = x % array_width;
r.y = x / array_width;
return r;
}
inline float ClampRad(float f)
{
f = math::fmod(f, TWOPI);
if (f < 0.0f) f += TWOPI;
return f;
}
inline void ClampRad(float* f)
{
*f = math::fmod(*f, TWOPI);
if (*f < 0.0f) *f += TWOPI;
}
inline bool RadsAreEqual(const float f1, const float f2)
{
return (math::fmod(f1 - f2, TWOPI) == 0.0f);
}
inline float GetRadFromXY(const float dx, const float dy)
{
float a;
if(dx != 0) {
a = math::atan(dy / dx);
if(dx < 0)
a += PI;
else if(dy < 0)
a += 2.0f * PI;
return a;
}
a = PI / 2.0f;
if(dy < 0)
a += PI;
return a;
}
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