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[spline/bezier]Make a bezier weights calculation class and precalcula…
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…te all bezier weights at the beginning.
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@xebra
xebra committed Oct 7, 2018
1 parent 3aeb320 commit 2a3210a
Showing 1 changed file with 62 additions and 42 deletions.
104 changes: 62 additions & 42 deletions GPU/Common/SplineCommon.cpp
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Original file line number Diff line number Diff line change
Expand Up @@ -60,20 +60,36 @@ static void BuildIndex(u16 *indices, int &count, int num_u, int num_v, GEPatchPr
}
}

// Bernstein basis functions
void Bernstein3DBasis(float x, float weights[4]) {
weights[0] = (1 - x) * (1 - x) * (1 - x);
weights[1] = 3 * x * (1 - x) * (1 - x);
weights[2] = 3 * x * x * (1 - x);
weights[3] = x * x * x;
}
struct Weight {
float weights[4], derivs[4];
};

void Bernstein3DDerivative(float x, float derivs[4]) {
derivs[0] = -3 * (x - 1) * (x - 1);
derivs[1] = 9 * x * x - 12 * x + 3;
derivs[2] = 3 * (2 - 3 * x) * x;
derivs[3] = 3 * x * x;
}
class Bezier3DWeight {
private:
void CalcWeights(float t, Weight &w) {
// Bernstein 3D basis polynomial
w.weights[0] = (1 - t) * (1 - t) * (1 - t);
w.weights[1] = 3 * t * (1 - t) * (1 - t);
w.weights[2] = 3 * t * t * (1 - t);
w.weights[3] = t * t * t;

// Derivative
w.derivs[0] = -3 * (1 - t) * (1 - t);
w.derivs[1] = 9 * t * t - 12 * t + 3;
w.derivs[2] = 3 * (2 - 3 * t) * t;
w.derivs[3] = 3 * t * t;
}
public:
Weight *CalcWeightsAll(int tess) {
Weight *weights = new Weight[tess + 1];
const float inv_u = 1.0f / (float)tess;
for (int i = 0; i < tess + 1; ++i) {
const float t = (float)i * inv_u;
CalcWeights(t, weights[i]);
}
return weights;
}
};

// http://en.wikipedia.org/wiki/Bernstein_polynomial
template<class T>
Expand Down Expand Up @@ -467,6 +483,14 @@ static void _BezierPatchHighQuality(u8 *&dest, u16 *&indices, int &count, int te
const bool sampleColors = (origVertType & GE_VTYPE_COL_MASK) != 0;
const bool sampleTexcoords = (origVertType & GE_VTYPE_TC_MASK) != 0;

Bezier3DWeight bezierWeight;
Weight *weights_u, *weights_v;
weights_u = bezierWeight.CalcWeightsAll(tess_u);
if (tess_u == tess_v)
weights_v = weights_u; // Use same weights
else
weights_v = bezierWeight.CalcWeightsAll(tess_u);

int num_patches_u = (patch.count_u - 1) / 3;
int num_patches_v = (patch.count_v - 1) / 3;
for (int patch_u = 0; patch_u < num_patches_u; ++patch_u) {
Expand All @@ -481,49 +505,43 @@ static void _BezierPatchHighQuality(u8 *&dest, u16 *&indices, int &count, int te
_col[point] = &patch.col[idx];
_tex[point] = &patch.tex[idx];
}
float weights[4], derivs[4];
for (int i = 0; i < tess_u + 1; i++) {
float u = ((float)i / (float)tess_u);
Bernstein3DBasis(u, weights);
prepos.horiz1[i] = Bernstein3D(*_pos[0], *_pos[1], *_pos[2], *_pos[3], weights);
prepos.horiz2[i] = Bernstein3D(*_pos[4], *_pos[5], *_pos[6], *_pos[7], weights);
prepos.horiz3[i] = Bernstein3D(*_pos[8], *_pos[9], *_pos[10], *_pos[11], weights);
prepos.horiz4[i] = Bernstein3D(*_pos[12], *_pos[13], *_pos[14], *_pos[15], weights);
Weight &wu = weights_u[i];
prepos.horiz1[i] = Bernstein3D(*_pos[0], *_pos[1], *_pos[2], *_pos[3], wu.weights);
prepos.horiz2[i] = Bernstein3D(*_pos[4], *_pos[5], *_pos[6], *_pos[7], wu.weights);
prepos.horiz3[i] = Bernstein3D(*_pos[8], *_pos[9], *_pos[10], *_pos[11], wu.weights);
prepos.horiz4[i] = Bernstein3D(*_pos[12], *_pos[13], *_pos[14], *_pos[15], wu.weights);

if (sampleColors) {
precol.horiz1[i] = Bernstein3D(*_col[0], *_col[1], *_col[2], *_col[3], weights);
precol.horiz2[i] = Bernstein3D(*_col[4], *_col[5], *_col[6], *_col[7], weights);
precol.horiz3[i] = Bernstein3D(*_col[8], *_col[9], *_col[10], *_col[11], weights);
precol.horiz4[i] = Bernstein3D(*_col[12], *_col[13], *_col[14], *_col[15], weights);
precol.horiz1[i] = Bernstein3D(*_col[0], *_col[1], *_col[2], *_col[3], wu.weights);
precol.horiz2[i] = Bernstein3D(*_col[4], *_col[5], *_col[6], *_col[7], wu.weights);
precol.horiz3[i] = Bernstein3D(*_col[8], *_col[9], *_col[10], *_col[11], wu.weights);
precol.horiz4[i] = Bernstein3D(*_col[12], *_col[13], *_col[14], *_col[15], wu.weights);
}
if (sampleTexcoords) {
pretex.horiz1[i] = Bernstein3D(*_tex[0], *_tex[1], *_tex[2], *_tex[3], weights);
pretex.horiz2[i] = Bernstein3D(*_tex[4], *_tex[5], *_tex[6], *_tex[7], weights);
pretex.horiz3[i] = Bernstein3D(*_tex[8], *_tex[9], *_tex[10], *_tex[11], weights);
pretex.horiz4[i] = Bernstein3D(*_tex[12], *_tex[13], *_tex[14], *_tex[15], weights);
pretex.horiz1[i] = Bernstein3D(*_tex[0], *_tex[1], *_tex[2], *_tex[3], wu.weights);
pretex.horiz2[i] = Bernstein3D(*_tex[4], *_tex[5], *_tex[6], *_tex[7], wu.weights);
pretex.horiz3[i] = Bernstein3D(*_tex[8], *_tex[9], *_tex[10], *_tex[11], wu.weights);
pretex.horiz4[i] = Bernstein3D(*_tex[12], *_tex[13], *_tex[14], *_tex[15], wu.weights);
}

if (computeNormals) {
Bernstein3DDerivative(u, derivs);
prederivU.horiz1[i] = Bernstein3D(*_pos[0], *_pos[1], *_pos[2], *_pos[3], derivs);
prederivU.horiz2[i] = Bernstein3D(*_pos[4], *_pos[5], *_pos[6], *_pos[7], derivs);
prederivU.horiz3[i] = Bernstein3D(*_pos[8], *_pos[9], *_pos[10], *_pos[11], derivs);
prederivU.horiz4[i] = Bernstein3D(*_pos[12], *_pos[13], *_pos[14], *_pos[15], derivs);
prederivU.horiz1[i] = Bernstein3D(*_pos[0], *_pos[1], *_pos[2], *_pos[3], wu.derivs);
prederivU.horiz2[i] = Bernstein3D(*_pos[4], *_pos[5], *_pos[6], *_pos[7], wu.derivs);
prederivU.horiz3[i] = Bernstein3D(*_pos[8], *_pos[9], *_pos[10], *_pos[11], wu.derivs);
prederivU.horiz4[i] = Bernstein3D(*_pos[12], *_pos[13], *_pos[14], *_pos[15], wu.derivs);
}
}

for (int tile_v = 0; tile_v < tess_v + 1; ++tile_v) {
for (int tile_u = 0; tile_u < tess_u + 1; ++tile_u) {
float u = ((float)tile_u / (float)tess_u);
float v = ((float)tile_v / (float)tess_v);

SimpleVertex &vert = vertices[tile_v * (tess_u + 1) + tile_u];

Bernstein3DBasis(v, weights);
Weight &wv = weights_v[tile_v];
if (computeNormals) {
Bernstein3DDerivative(v, derivs);
const Vec3f derivU = prederivU.Bernstein3D(tile_u, weights);
const Vec3f derivV = prepos.Bernstein3D(tile_u, derivs);
const Vec3f derivU = prederivU.Bernstein3D(tile_u, wv.weights);
const Vec3f derivV = prepos.Bernstein3D(tile_u, wv.derivs);

vert.nrm = Cross(derivU, derivV).Normalized();
if (patch.patchFacing)
Expand All @@ -532,21 +550,23 @@ static void _BezierPatchHighQuality(u8 *&dest, u16 *&indices, int &count, int te
vert.nrm.SetZero();
}

vert.pos = prepos.Bernstein3D(tile_u, weights);
vert.pos = prepos.Bernstein3D(tile_u, wv.weights);

if (!sampleTexcoords) {
float u = ((float)tile_u / (float)tess_u);
float v = ((float)tile_v / (float)tess_v);
// Generate texcoord
vert.uv[0] = u + patch_u * third;
vert.uv[1] = v + patch_u * third;
} else {
// Sample UV from control points
const Vec2f res = pretex.Bernstein3D(tile_u, weights);
const Vec2f res = pretex.Bernstein3D(tile_u, wv.weights);
vert.uv[0] = res.x;
vert.uv[1] = res.y;
}

if (sampleColors) {
vert.color_32 = precol.Bernstein3D(tile_u, weights).ToRGBA();
vert.color_32 = precol.Bernstein3D(tile_u, wv.weights).ToRGBA();
} else {
vert.color_32 = patch.defcolor;
}
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