*/
#include "quakedef.h"
+#include "mathlib.h"
#include <math.h>
#include "curves.h"
+// Calculate number of resulting vertex rows/columns by given patch size and tesselation factor
+// tess=0 means that we reduce detalization of base 3x3 patches by removing middle row and column of vertices
+// "DimForTess" is "DIMension FOR TESSelation factor"
+// NB: tess=0 actually means that tess must be 0.5, but obviously it can't because it is of int type. (so "a*tess"-like code is replaced by "a/2" if tess=0)
+int Q3PatchDimForTess(int size, int tess)
+{
+ if (tess > 0)
+ return (size - 1) * tess + 1;
+ else if (tess == 0)
+ return (size - 1) / 2 + 1;
+ else
+ return 0; // Maybe warn about wrong tess here?
+}
+
// usage:
// to expand a 5x5 patch to 21x21 vertices (4x4 tesselation), one might use this call:
// Q3PatchSubdivideFloat(3, sizeof(float[3]), outvertices, 5, 5, sizeof(float[3]), patchvertices, 4, 4);
void Q3PatchTesselateFloat(int numcomponents, int outputstride, float *outputvertices, int patchwidth, int patchheight, int inputstride, float *patchvertices, int tesselationwidth, int tesselationheight)
{
- int k, l, x, y, component, outputwidth = (patchwidth-1)*tesselationwidth+1;
+ int k, l, x, y, component, outputwidth = Q3PatchDimForTess(patchwidth, tesselationwidth);
float px, py, *v, a, b, c, *cp[3][3], temp[3][64];
+ int xmax = max(1, 2*tesselationwidth);
+ int ymax = max(1, 2*tesselationheight);
+
// iterate over the individual 3x3 quadratic spline surfaces one at a time
// expanding them to fill the output array (with some overlap to ensure
// the edges are filled)
for (x = 0;x < 3;x++)
cp[y][x] = (float *)((unsigned char *)patchvertices + ((k+y)*patchwidth+(l+x)) * inputstride);
// for each row...
- for (y = 0;y <= tesselationheight*2;y++)
+ for (y = 0;y <= ymax;y++)
{
// calculate control points for this row by collapsing the 3
// rows of control points to one row using py
- py = (float)y / (float)(tesselationheight*2);
+ py = (float)y / (float)ymax;
// calculate quadratic spline weights for py
a = ((1.0f - py) * (1.0f - py));
b = ((1.0f - py) * (2.0f * py));
temp[2][component] = cp[0][2][component] * a + cp[1][2][component] * b + cp[2][2][component] * c;
}
// fetch a pointer to the beginning of the output vertex row
- v = (float *)((unsigned char *)outputvertices + ((k * tesselationheight + y) * outputwidth + l * tesselationwidth) * outputstride);
+ v = (float *)((unsigned char *)outputvertices + ((k * ymax / 2 + y) * outputwidth + l * xmax / 2) * outputstride);
// for each column of the row...
- for (x = 0;x <= (tesselationwidth*2);x++)
+ for (x = 0;x <= xmax;x++)
{
// calculate point based on the row control points
- px = (float)x / (float)(tesselationwidth*2);
+ px = (float)x / (float)xmax;
// calculate quadratic spline weights for px
// (could be precalculated)
a = ((1.0f - px) * (1.0f - px));
#endif
}
+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(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(2.0f)) + 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)
+ // maps [1..2[ to 1
+ // maps [2..4[ to 2
+ // maps [4..8[ to 4
+}
+
+static float Squared3xCurveArea(const float *a, const float *control, const float *b, int components)
+{
+#if 0
+ // mimicing the old behaviour with the new code...
+
+ float deviation;
+ float quartercurvearea = 0;
+ int c;
+ for (c = 0;c < components;c++)
+ {
+ deviation = control[c] * 0.5f - a[c] * 0.25f - b[c] * 0.25f;
+ quartercurvearea += deviation*deviation;
+ }
+
+ // But as the new code now works on the squared 2x curve area, let's scale the value
+ return quartercurvearea * quartercurvearea * 64.0;
+
+#else
+ // ideally, we'd like the area between the spline a->control->b and the line a->b.
+ // 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:
+ //
+ // the area between the spline and the line a->b is a measure of the
+ // error of approximation of the spline by the line.
+ //
+ // 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...
+ //
+ // let's calculate the area! but we have to avoid the cross product, as
+ // components is not necessarily 3
+ //
+ // the area of a triangle spanned by vectors a and b is
+ //
+ // 0.5 * |a| |b| sin gamma
+ //
+ // now, cos gamma is
+ //
+ // a.b / (|a| |b|)
+ //
+ // so the area is
+ //
+ // 0.5 * sqrt(|a|^2 |b|^2 - (a.b)^2)
+ int c;
+ float aa = 0, bb = 0, ab = 0;
+ for (c = 0;c < components;c++)
+ {
+ float xa = a[c] - control[c];
+ float xb = b[c] - control[c];
+ aa += xa * xa;
+ ab += xa * xb;
+ bb += xb * xb;
+ }
+ // area is 0.5 * 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
+}
+
// returns how much tesselation of each segment is needed to remain under tolerance
int Q3PatchTesselationOnX(int patchwidth, int patchheight, int components, const float *in, float tolerance)
{
- int c, x, y;
+ int x, y;
const float *patch;
- float deviation, squareddeviation, bestsquareddeviation;
- bestsquareddeviation = 0;
+ float squared3xcurvearea, largestsquared3xcurvearea;
+ largestsquared3xcurvearea = 0;
for (y = 0;y < patchheight;y++)
{
for (x = 0;x < patchwidth-1;x += 2)
{
- squareddeviation = 0;
- for (c = 0, patch = in + ((y * patchwidth) + x) * components;c < components;c++, patch++)
- {
- deviation = patch[components] * 0.5f - patch[0] * 0.25f - patch[2*components] * 0.25f;
- squareddeviation += deviation*deviation;
- }
- if (bestsquareddeviation < squareddeviation)
- bestsquareddeviation = squareddeviation;
+ patch = in + ((y * patchwidth) + x) * components;
+ squared3xcurvearea = Squared3xCurveArea(&patch[0], &patch[components], &patch[2*components], components);
+ if (largestsquared3xcurvearea < squared3xcurvearea)
+ largestsquared3xcurvearea = squared3xcurvearea;
}
}
- return (int)floor(log(sqrt(bestsquareddeviation) / tolerance) / log(2)) + 1;
+ return Q3PatchTesselation(largestsquared3xcurvearea, tolerance);
}
// returns how much tesselation of each segment is needed to remain under tolerance
int Q3PatchTesselationOnY(int patchwidth, int patchheight, int components, const float *in, float tolerance)
{
- int c, x, y;
+ int x, y;
const float *patch;
- float deviation, squareddeviation, bestsquareddeviation;
- bestsquareddeviation = 0;
+ float squared3xcurvearea, largestsquared3xcurvearea;
+ largestsquared3xcurvearea = 0;
for (y = 0;y < patchheight-1;y += 2)
{
for (x = 0;x < patchwidth;x++)
{
- squareddeviation = 0;
- for (c = 0, patch = in + ((y * patchwidth) + x) * components;c < components;c++, patch++)
+ patch = in + ((y * patchwidth) + x) * components;
+ squared3xcurvearea = Squared3xCurveArea(&patch[0], &patch[patchwidth*components], &patch[2*patchwidth*components], components);
+ if (largestsquared3xcurvearea < squared3xcurvearea)
+ largestsquared3xcurvearea = squared3xcurvearea;
+ }
+ }
+ return Q3PatchTesselation(largestsquared3xcurvearea, tolerance);
+}
+
+// Find an equal vertex in array. Check only vertices with odd X and Y
+static int FindEqualOddVertexInArray(int numcomponents, float *vertex, float *vertices, int width, int height)
+{
+ int x, y, j;
+ for (y=0; y<height; y+=2)
+ {
+ for (x=0; x<width; x+=2)
+ {
+ qboolean found = true;
+ for (j=0; j<numcomponents; j++)
+ if (fabs(*(vertex+j) - *(vertices+j)) > 0.05)
+ // div0: this is notably smaller than the smallest radiant grid
+ // but large enough so we don't need to get scared of roundoff
+ // errors
+ {
+ found = false;
+ break;
+ }
+ if(found)
+ return y*width+x;
+ vertices += numcomponents*2;
+ }
+ vertices += numcomponents*(width-1);
+ }
+ return -1;
+}
+
+#define SIDE_INVALID -1
+#define SIDE_X 0
+#define SIDE_Y 1
+
+static int GetSide(int p1, int p2, int width, int height, int *pointdist)
+{
+ int x1 = p1 % width, y1 = p1 / width;
+ int x2 = p2 % width, y2 = p2 / width;
+ if (p1 < 0 || p2 < 0)
+ return SIDE_INVALID;
+ if (x1 == x2)
+ {
+ if (y1 != y2)
+ {
+ *pointdist = abs(y2 - y1);
+ return SIDE_Y;
+ }
+ else
+ return SIDE_INVALID;
+ }
+ else if (y1 == y2)
+ {
+ *pointdist = abs(x2 - x1);
+ return SIDE_X;
+ }
+ else
+ return SIDE_INVALID;
+}
+
+// Increase tesselation of one of two touching patches to make a seamless connection between them
+// Returns 0 in case if patches were not modified, otherwise 1
+int Q3PatchAdjustTesselation(int numcomponents, patchinfo_t *patch1, float *patchvertices1, patchinfo_t *patch2, float *patchvertices2)
+{
+ // what we are doing here is:
+ // we take for each corner of one patch
+ // and check if the other patch contains that corner
+ // once we have a pair of such matches
+
+ struct {int id1,id2;} commonverts[8];
+ int i, j, k, side1, side2, *tess1, *tess2;
+ int dist1 = 0, dist2 = 0;
+ qboolean modified = false;
+
+ // Potential paired vertices (corners of the first patch)
+ commonverts[0].id1 = 0;
+ commonverts[1].id1 = patch1->xsize-1;
+ commonverts[2].id1 = patch1->xsize*(patch1->ysize-1);
+ commonverts[3].id1 = patch1->xsize*patch1->ysize-1;
+ for (i=0;i<4;++i)
+ commonverts[i].id2 = FindEqualOddVertexInArray(numcomponents, patchvertices1+numcomponents*commonverts[i].id1, patchvertices2, patch2->xsize, patch2->ysize);
+
+ // Corners of the second patch
+ commonverts[4].id2 = 0;
+ commonverts[5].id2 = patch2->xsize-1;
+ commonverts[6].id2 = patch2->xsize*(patch2->ysize-1);
+ commonverts[7].id2 = patch2->xsize*patch2->ysize-1;
+ for (i=4;i<8;++i)
+ commonverts[i].id1 = FindEqualOddVertexInArray(numcomponents, patchvertices2+numcomponents*commonverts[i].id2, patchvertices1, patch1->xsize, patch1->ysize);
+
+ for (i=0;i<8;++i)
+ for (j=i+1;j<8;++j)
+ {
+ side1 = GetSide(commonverts[i].id1,commonverts[j].id1,patch1->xsize,patch1->ysize,&dist1);
+ side2 = GetSide(commonverts[i].id2,commonverts[j].id2,patch2->xsize,patch2->ysize,&dist2);
+
+ if (side1 == SIDE_INVALID || side2 == SIDE_INVALID)
+ continue;
+
+ if(dist1 != dist2)
+ {
+ // no patch welding if the resolutions mismatch
+ continue;
+ }
+
+ // Update every lod level
+ for (k=0;k<PATCH_LODS_NUM;++k)
{
- deviation = patch[patchwidth*components] * 0.5f - patch[0] * 0.25f - patch[2*patchwidth*components] * 0.25f;
- squareddeviation += deviation*deviation;
+ tess1 = side1 == SIDE_X ? &patch1->lods[k].xtess : &patch1->lods[k].ytess;
+ tess2 = side2 == SIDE_X ? &patch2->lods[k].xtess : &patch2->lods[k].ytess;
+ if (*tess1 != *tess2)
+ {
+ if (*tess1 < *tess2)
+ *tess1 = *tess2;
+ else
+ *tess2 = *tess1;
+ modified = true;
+ }
}
- if (bestsquareddeviation < squareddeviation)
- bestsquareddeviation = squareddeviation;
}
- }
- return (int)floor(log(sqrt(bestsquareddeviation) / tolerance) / log(2)) + 1;
+
+ return modified;
}
+#undef SIDE_INVALID
+#undef SIDE_X
+#undef SIDE_Y
+
// calculates elements for a grid of vertices
// (such as those produced by Q3PatchTesselate)
// (note: width and height are the actual vertex size, this produces
-// (width-1)*(height-1)*2 triangles, 3 elements each)
+// (width-1)*(height-1)*2 triangles, 3 elements each)
void Q3PatchTriangleElements(int *elements, int width, int height, int firstvertex)
{
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++;
+ }
}
}
}
projects / xonotic / darkplaces.git / blobdiff