Fix setinfo.
[xonotic/darkplaces.git] / curves.c
index ea18cf4..cf7569d 100644 (file)
--- a/curves.c
+++ b/curves.c
@@ -136,18 +136,18 @@ void Q3PatchTesselateFloat(int numcomponents, int outputstride, float *outputver
 #endif
 }
 
-static int Q3PatchTesselation(float largestsquared2xcurvearea, float tolerance)
+static int Q3PatchTesselation(float largestsquared3xcurvearea, float tolerance)
 {
        float f;
        // f is actually a squared 2x curve area... so the formula had to be adjusted to give roughly the same subdivisions
-       f = pow(largestsquared2xcurvearea / 64.0, 0.25) / tolerance;
+       f = pow(largestsquared3xcurvearea / 64.0f, 0.25f) / tolerance;
        //if(f < 0.25) // VERY flat patches
        if(f < 0.0001) // TOTALLY flat patches
                return 0;
        else if(f < 2)
                return 1;
        else
-               return (int) floor(log(f) / log(2)) + 1;
+               return (int) floor(log(f) / log(2.0f)) + 1;
                // this is always at least 2
                // maps [0.25..0.5[ to -1 (actually, 1 is returned)
                // maps [0.5..1[ to 0 (actually, 1 is returned)
@@ -156,7 +156,7 @@ static int Q3PatchTesselation(float largestsquared2xcurvearea, float tolerance)
                // maps [4..8[ to 4
 }
 
-float Squared2xCurveArea(const float *a, const float *control, const float *b, int components)
+static float Squared3xCurveArea(const float *a, const float *control, const float *b, int components)
 {
 #if 0
        // mimicing the old behaviour with the new code...
@@ -178,6 +178,13 @@ float Squared2xCurveArea(const float *a, const float *control, const float *b, i
        // but as this is hard to calculate, let's calculate an upper bound of it:
        // the area of the triangle a->control->b->a.
        //
+       // one can prove that the area of a quadratic spline = 2/3 * the area of
+       // the triangle of its control points!
+       // to do it, first prove it for the spline through (0,0), (1,1), (2,0)
+       // (which is a parabola) and then note that moving the control point
+       // left/right is just shearing and keeps the area of both the spline and
+       // the triangle invariant.
+       //
        // why are we going for the spline area anyway?
        // we know that:
        //
@@ -186,6 +193,8 @@ float Squared2xCurveArea(const float *a, const float *control, const float *b, i
        //
        //   also, on circle-like or parabola-like curves, you easily get that the
        //   double amount of line approximation segments reduces the error to its quarter
+       //   (also, easy to prove for splines by doing it for one specific one, and using
+       //   affine transforms to get all other splines)
        //
        // so...
        //
@@ -214,7 +223,8 @@ float Squared2xCurveArea(const float *a, const float *control, const float *b, i
                bb += xb * xb;
        }
        // area is 0.5 * sqrt(aa*bb - ab*ab)
-       // 2x area is sqrt(aa*bb - ab*ab)
+       // 2x TRIANGLE area is sqrt(aa*bb - ab*ab)
+       // 3x CURVE area is sqrt(aa*bb - ab*ab)
        return aa * bb - ab * ab;
 #endif
 }
@@ -224,19 +234,19 @@ int Q3PatchTesselationOnX(int patchwidth, int patchheight, int components, const
 {
        int x, y;
        const float *patch;
-       float squared2xcurvearea, largestsquared2xcurvearea;
-       largestsquared2xcurvearea = 0;
+       float squared3xcurvearea, largestsquared3xcurvearea;
+       largestsquared3xcurvearea = 0;
        for (y = 0;y < patchheight;y++)
        {
                for (x = 0;x < patchwidth-1;x += 2)
                {
                        patch = in + ((y * patchwidth) + x) * components;
-                       squared2xcurvearea = Squared2xCurveArea(&patch[0], &patch[components], &patch[2*components], components);
-                       if (largestsquared2xcurvearea < squared2xcurvearea)
-                               largestsquared2xcurvearea = squared2xcurvearea;
+                       squared3xcurvearea = Squared3xCurveArea(&patch[0], &patch[components], &patch[2*components], components);
+                       if (largestsquared3xcurvearea < squared3xcurvearea)
+                               largestsquared3xcurvearea = squared3xcurvearea;
                }
        }
-       return Q3PatchTesselation(largestsquared2xcurvearea, tolerance);
+       return Q3PatchTesselation(largestsquared3xcurvearea, tolerance);
 }
 
 // returns how much tesselation of each segment is needed to remain under tolerance
@@ -244,19 +254,19 @@ int Q3PatchTesselationOnY(int patchwidth, int patchheight, int components, const
 {
        int x, y;
        const float *patch;
-       float squared2xcurvearea, largestsquared2xcurvearea;
-       largestsquared2xcurvearea = 0;
+       float squared3xcurvearea, largestsquared3xcurvearea;
+       largestsquared3xcurvearea = 0;
        for (y = 0;y < patchheight-1;y += 2)
        {
                for (x = 0;x < patchwidth;x++)
                {
                        patch = in + ((y * patchwidth) + x) * components;
-                       squared2xcurvearea = Squared2xCurveArea(&patch[0], &patch[patchwidth*components], &patch[2*patchwidth*components], components);
-                       if (largestsquared2xcurvearea < squared2xcurvearea)
-                               largestsquared2xcurvearea = squared2xcurvearea;
+                       squared3xcurvearea = Squared3xCurveArea(&patch[0], &patch[patchwidth*components], &patch[2*patchwidth*components], components);
+                       if (largestsquared3xcurvearea < squared3xcurvearea)
+                               largestsquared3xcurvearea = squared3xcurvearea;
                }
        }
-       return Q3PatchTesselation(largestsquared2xcurvearea, tolerance);
+       return Q3PatchTesselation(largestsquared3xcurvearea, tolerance);
 }
 
 // Find an equal vertex in array. Check only vertices with odd X and Y
@@ -326,7 +336,7 @@ int Q3PatchAdjustTesselation(int numcomponents, patchinfo_t *patch1, float *patc
 
        struct {int id1,id2;} commonverts[8];
        int i, j, k, side1, side2, *tess1, *tess2;
-       int dist1, dist2;
+       int dist1 = 0, dist2 = 0;
        qboolean modified = false;
 
        // Potential paired vertices (corners of the first patch)
@@ -392,18 +402,38 @@ void Q3PatchTriangleElements(int *elements, int width, int height, int firstvert
        int x, y, row0, row1;
        for (y = 0;y < height - 1;y++)
        {
-               row0 = firstvertex + (y + 0) * width;
-               row1 = firstvertex + (y + 1) * width;
-               for (x = 0;x < width - 1;x++)
+               if(y % 2)
+               {
+                       // swap the triangle order in odd rows as optimization for collision stride
+                       row0 = firstvertex + (y + 0) * width + width - 2;
+                       row1 = firstvertex + (y + 1) * width + width - 2;
+                       for (x = 0;x < width - 1;x++)
+                       {
+                               *elements++ = row1;
+                               *elements++ = row1 + 1;
+                               *elements++ = row0 + 1;
+                               *elements++ = row0;
+                               *elements++ = row1;
+                               *elements++ = row0 + 1;
+                               row0--;
+                               row1--;
+                       }
+               }
+               else
                {
-                       *elements++ = row0;
-                       *elements++ = row1;
-                       *elements++ = row0 + 1;
-                       *elements++ = row1;
-                       *elements++ = row1 + 1;
-                       *elements++ = row0 + 1;
-                       row0++;
-                       row1++;
+                       row0 = firstvertex + (y + 0) * width;
+                       row1 = firstvertex + (y + 1) * width;
+                       for (x = 0;x < width - 1;x++)
+                       {
+                               *elements++ = row0;
+                               *elements++ = row1;
+                               *elements++ = row0 + 1;
+                               *elements++ = row1;
+                               *elements++ = row1 + 1;
+                               *elements++ = row0 + 1;
+                               row0++;
+                               row1++;
+                       }
                }
        }
 }