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- use the FP2005 method to calculate xtoviewangle, because it is far more straightforward than the old version.

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This commit is contained in:
Christoph Oelckers 2016-04-28 16:27:28 +02:00
parent ef98757c7c
commit af2a1769d8
1 changed files with 10 additions and 54 deletions
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64
src/r_main.cpp
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@ -165,33 +165,6 @@ static int lastcenteryfrac;
// CODE --------------------------------------------------------------------
//==========================================================================
//
// viewangletox
//
// Used solely for construction the xtoviewangle table.
//
//==========================================================================
static inline int viewangletox(int i)
{
const double pimul = M_PI / 4096;
// Don't waste time calculating the tangent of values outside the valid range.
// Checking the index where tan(i) becomes too large is a lot faster
if (i <= 604) // 604 is the highest index with tan < -2
{
return viewwidth + 1;
}
else if (i >= 4096 - 604) // same as above with reversed signs
{
return -1;
}
double t = tan((i - 2048)*pimul) * FocalLengthX;
return clamp(xs_CeilToInt(CenterX - t), -1, viewwidth+1);
}
//==========================================================================
//
// R_InitTextureMapping
@ -200,46 +173,29 @@ static inline int viewangletox(int i)
void R_InitTextureMapping ()
{
int i, x;
int i;
// Calc focallength so FieldOfView fineangles covers viewwidth.
// Calc focallength so FieldOfView angles cover viewwidth.
FocalLengthX = CenterX / FocalTangent;
FocalLengthY = FocalLengthX * YaspectMul;
// This is 1/FocalTangent before the widescreen extension of FOV.
viewingrangerecip = FLOAT2FIXED(1. / tan(FieldOfView.Radians() / 2));
// [RH] Do not generate viewangletox, because texture mapping is no
// longer done with trig, so it's not needed.
// Now generate xtoviewangle for sky texture mapping.
// We do this with a hybrid approach: The center 90 degree span is
// constructed as per the original code:
// Scan xtoviewangle to find the smallest view angle that maps to x.
// (viewangletox is sorted in non-increasing order.)
// This reduces the chances of "doubling-up" of texture columns in
// the drawn sky texture.
// The remaining arcs are done with tantoangle instead.
// [RH] Do not generate viewangletox, because texture mapping is no
// longer done with trig, so it's not needed.
const double slopestep = FocalTangent / centerx;
double slope;
const int t1 = MAX(int(CenterX - FocalLengthX), 0);
const int t2 = MIN(int(CenterX + FocalLengthX), viewwidth);
for (i = 0, x = t2; x >= t1; --x)
for (i = centerx, slope = 0; i <= viewwidth; i++, slope += slopestep)
{
while (viewangletox(i) > x)
{
++i;
}
xtoviewangle[x] = (i << 19) - ANGLE_90;
xtoviewangle[i] = angle_t((2 * M_PI - atan(slope)) * (ANGLE_180 / M_PI));
}
for (x = t2 + 1; x <= viewwidth; ++x)
for (i = 0; i < centerx; i++)
{
double f = atan2((FocalLengthX / (x - centerx)), 1) / (2*M_PI);
xtoviewangle[x] = ANGLE_270 + (angle_t)(0xffffffff * f);
}
for (x = 0; x < t1; ++x)
{
xtoviewangle[x] = (angle_t)(-(signed)xtoviewangle[viewwidth - x]);
xtoviewangle[i] = 0 - xtoviewangle[viewwidth - i - 1];
}
}