blender/intern/cycles/subd/subd_dice.cpp

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/*
* Copyright 2011, Blender Foundation.
*
* This program is free software; you can redistribute it and/or
* modify it under the terms of the GNU General Public License
* as published by the Free Software Foundation; either version 2
* of the License, or (at your option) any later version.
*
* This program is distributed in the hope that it will be useful,
* but WITHOUT ANY WARRANTY; without even the implied warranty of
* MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
* GNU General Public License for more details.
*
* You should have received a copy of the GNU General Public License
* along with this program; if not, write to the Free Software Foundation,
* Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
*/
#include "camera.h"
#include "mesh.h"
#include "subd_dice.h"
#include "subd_patch.h"
#include "util_debug.h"
CCL_NAMESPACE_BEGIN
/* EdgeDice Base */
EdgeDice::EdgeDice(Mesh *mesh_, int shader_, bool smooth_, float dicing_rate_)
{
mesh = mesh_;
mesh_P = NULL;
mesh_N = NULL;
vert_offset = 0;
dicing_rate = dicing_rate_;
shader = shader_;
smooth = smooth_;
camera = NULL;
mesh->attributes.add(ATTR_STD_VERTEX_NORMAL);
}
void EdgeDice::reserve(int num_verts, int num_tris)
{
vert_offset = mesh->verts.size();
tri_offset = mesh->triangles.size();
mesh->reserve(vert_offset + num_verts, tri_offset + num_tris);
Attribute *attr_vN = mesh->attributes.add(ATTR_STD_VERTEX_NORMAL);
mesh_P = &mesh->verts[0];
mesh_N = attr_vN->data_float3();
}
int EdgeDice::add_vert(Patch *patch, float2 uv)
{
float3 P, N, dPdu, dPdv;
patch->eval(&P, &dPdu, &dPdv, uv.x, uv.y);
N = normalize(cross(dPdu, dPdv));
assert(vert_offset < mesh->verts.size());
mesh_P[vert_offset] = P;
mesh_N[vert_offset] = N;
return vert_offset++;
}
void EdgeDice::add_triangle(int v0, int v1, int v2)
{
mesh->add_triangle(v0, v1, v2, shader, smooth);
}
void EdgeDice::stitch_triangles(vector<int>& outer, vector<int>& inner)
{
if(inner.size() == 0 || outer.size() == 0)
return; // XXX avoid crashes for Mu or Mv == 1, missing polygons
/* stitch together two arrays of verts with triangles. at each step,
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* we compare using the next verts on both sides, to find the split
* direction with the smallest diagonal, and use that in order to keep
* the triangle shape reasonable. */
for(size_t i = 0, j = 0; i+1 < inner.size() || j+1 < outer.size();) {
int v0, v1, v2;
v0 = inner[i];
v1 = outer[j];
if(j+1 == outer.size()) {
v2 = inner[++i];
}
else if(i+1 == inner.size()) {
v2 = outer[++j];
}
else {
/* length of diagonals */
float len1 = len(mesh_P[inner[i]] - mesh_P[outer[j+1]]);
float len2 = len(mesh_P[outer[j]] - mesh_P[inner[i+1]]);
/* use smallest diagonal */
if(len1 < len2)
v2 = outer[++j];
else
v2 = inner[++i];
}
add_triangle(v0, v1, v2);
}
}
/* QuadDice */
QuadDice::QuadDice(Mesh *mesh_, int shader_, bool smooth_, float dicing_rate_)
: EdgeDice(mesh_, shader_, smooth_, dicing_rate_)
{
}
void QuadDice::reserve(EdgeFactors& ef, int Mu, int Mv)
{
/* XXX need to make this also work for edge factor 0 and 1 */
int num_verts = (ef.tu0 + ef.tu1 + ef.tv0 + ef.tv1) + (Mu - 1)*(Mv - 1);
EdgeDice::reserve(num_verts, 0);
}
float2 QuadDice::map_uv(SubPatch& sub, float u, float v)
{
/* map UV from subpatch to patch parametric coordinates */
float2 d0 = interp(sub.P00, sub.P01, v);
float2 d1 = interp(sub.P10, sub.P11, v);
return interp(d0, d1, u);
}
float3 QuadDice::eval_projected(SubPatch& sub, float u, float v)
{
float2 uv = map_uv(sub, u, v);
float3 P;
sub.patch->eval(&P, NULL, NULL, uv.x, uv.y);
if(camera)
P = transform_perspective(&camera->worldtoraster, P);
return P;
}
int QuadDice::add_vert(SubPatch& sub, float u, float v)
{
return EdgeDice::add_vert(sub.patch, map_uv(sub, u, v));
}
void QuadDice::add_side_u(SubPatch& sub,
vector<int>& outer, vector<int>& inner,
int Mu, int Mv, int tu, int side, int offset)
{
outer.clear();
inner.clear();
/* set verts on the edge of the patch */
outer.push_back(offset + ((side)? 2: 0));
for(int i = 1; i < tu; i++) {
float u = i/(float)tu;
float v = (side)? 1.0f: 0.0f;
outer.push_back(add_vert(sub, u, v));
}
outer.push_back(offset + ((side)? 3: 1));
/* set verts on the edge of the inner grid */
for(int i = 0; i < Mu-1; i++) {
int j = (side)? Mv-1-1: 0;
inner.push_back(offset + 4 + i + j*(Mu-1));
}
}
void QuadDice::add_side_v(SubPatch& sub,
vector<int>& outer, vector<int>& inner,
int Mu, int Mv, int tv, int side, int offset)
{
outer.clear();
inner.clear();
/* set verts on the edge of the patch */
outer.push_back(offset + ((side)? 1: 0));
for(int j = 1; j < tv; j++) {
float u = (side)? 1.0f: 0.0f;
float v = j/(float)tv;
outer.push_back(add_vert(sub, u, v));
}
outer.push_back(offset + ((side)? 3: 2));
/* set verts on the edge of the inner grid */
for(int j = 0; j < Mv-1; j++) {
int i = (side)? Mu-1-1: 0;
inner.push_back(offset + 4 + i + j*(Mu-1));
}
}
float QuadDice::quad_area(const float3& a, const float3& b, const float3& c, const float3& d)
{
return triangle_area(a, b, d) + triangle_area(a, d, c);
}
float QuadDice::scale_factor(SubPatch& sub, EdgeFactors& ef, int Mu, int Mv)
{
/* estimate area as 4x largest of 4 quads */
float3 P[3][3];
for(int i = 0; i < 3; i++)
for(int j = 0; j < 3; j++)
P[i][j] = eval_projected(sub, i*0.5f, j*0.5f);
float A1 = quad_area(P[0][0], P[1][0], P[0][1], P[1][1]);
float A2 = quad_area(P[1][0], P[2][0], P[1][1], P[2][1]);
float A3 = quad_area(P[0][1], P[1][1], P[0][2], P[1][2]);
float A4 = quad_area(P[1][1], P[2][1], P[1][2], P[2][2]);
float Apatch = max(A1, max(A2, max(A3, A4)))*4.0f;
/* solve for scaling factor */
float Atri = dicing_rate*dicing_rate*0.5f;
float Ntris = Apatch/Atri;
// XXX does the -sqrt solution matter
// XXX max(D, 0.0) is highly suspicious, need to test cases
// where D goes negative
float N = 0.5f*(Ntris - (ef.tu0 + ef.tu1 + ef.tv0 + ef.tv1));
float D = 4.0f*N*Mu*Mv + (Mu + Mv)*(Mu + Mv);
float S = (Mu + Mv + sqrtf(max(D, 0.0f)))/(2*Mu*Mv);
return S;
}
void QuadDice::add_corners(SubPatch& sub)
{
/* add verts for patch corners */
if(sub.patch->is_triangle()) {
add_vert(sub, 0.0f, 0.0f);
add_vert(sub, 1.0f, 0.0f);
add_vert(sub, 0.0f, 1.0f);
}
else {
add_vert(sub, 0.0f, 0.0f);
add_vert(sub, 1.0f, 0.0f);
add_vert(sub, 0.0f, 1.0f);
add_vert(sub, 1.0f, 1.0f);
}
}
void QuadDice::add_grid(SubPatch& sub, int Mu, int Mv, int offset)
{
/* create inner grid */
float du = 1.0f/(float)Mu;
float dv = 1.0f/(float)Mv;
for(int j = 1; j < Mv; j++) {
for(int i = 1; i < Mu; i++) {
float u = i*du;
float v = j*dv;
add_vert(sub, u, v);
if(i < Mu-1 && j < Mv-1) {
int i1 = offset + 4 + (i-1) + (j-1)*(Mu-1);
int i2 = offset + 4 + i + (j-1)*(Mu-1);
int i3 = offset + 4 + i + j*(Mu-1);
int i4 = offset + 4 + (i-1) + j*(Mu-1);
add_triangle(i1, i2, i3);
add_triangle(i1, i3, i4);
}
}
}
}
void QuadDice::dice(SubPatch& sub, EdgeFactors& ef)
{
/* compute inner grid size with scale factor */
int Mu = max(ef.tu0, ef.tu1);
int Mv = max(ef.tv0, ef.tv1);
float S = scale_factor(sub, ef, Mu, Mv);
Mu = max((int)ceil(S*Mu), 2); // XXX handle 0 & 1?
Mv = max((int)ceil(S*Mv), 2); // XXX handle 0 & 1?
/* reserve space for new verts */
int offset = mesh->verts.size();
reserve(ef, Mu, Mv);
/* corners and inner grid */
add_corners(sub);
add_grid(sub, Mu, Mv, offset);
/* bottom side */
vector<int> outer, inner;
add_side_u(sub, outer, inner, Mu, Mv, ef.tu0, 0, offset);
stitch_triangles(outer, inner);
/* top side */
add_side_u(sub, outer, inner, Mu, Mv, ef.tu1, 1, offset);
stitch_triangles(inner, outer);
/* left side */
add_side_v(sub, outer, inner, Mu, Mv, ef.tv0, 0, offset);
stitch_triangles(inner, outer);
/* right side */
add_side_v(sub, outer, inner, Mu, Mv, ef.tv1, 1, offset);
stitch_triangles(outer, inner);
assert(vert_offset == mesh->verts.size());
}
/* TriangleDice */
TriangleDice::TriangleDice(Mesh *mesh_, int shader_, bool smooth_, float dicing_rate_)
: EdgeDice(mesh_, shader_, smooth_, dicing_rate_)
{
}
void TriangleDice::reserve(EdgeFactors& ef, int M)
{
int num_verts = ef.tu + ef.tv + ef.tw;
for(int m = M-2; m > 0; m -= 2)
num_verts += 3 + (m-1)*3;
if(!(M & 1))
num_verts++;
EdgeDice::reserve(num_verts, 0);
}
float2 TriangleDice::map_uv(SubPatch& sub, float2 uv)
{
/* map UV from subpatch to patch parametric coordinates */
return uv.x*sub.Pu + uv.y*sub.Pv + (1.0f - uv.x - uv.y)*sub.Pw;
}
int TriangleDice::add_vert(SubPatch& sub, float2 uv)
{
return EdgeDice::add_vert(sub.patch, map_uv(sub, uv));
}
void TriangleDice::add_grid(SubPatch& sub, EdgeFactors& ef, int M)
{
// XXX normals are flipped, why?
/* grid is constructed starting from the outside edges, and adding
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* progressively smaller inner triangles that connected to the outer
* one, until M = 1 or 2, the we fill up the last part. */
vector<int> outer_u, outer_v, outer_w;
int m;
/* add outer corners vertices */
{
float2 p_u = make_float2(1.0f, 0.0f);
float2 p_v = make_float2(0.0f, 1.0f);
float2 p_w = make_float2(0.0f, 0.0f);
int corner_u = add_vert(sub, p_u);
int corner_v = add_vert(sub, p_v);
int corner_w = add_vert(sub, p_w);
outer_u.push_back(corner_v);
outer_v.push_back(corner_w);
outer_w.push_back(corner_u);
for(int i = 1; i < ef.tu; i++)
outer_u.push_back(add_vert(sub, interp(p_v, p_w, i/(float)ef.tu)));
for(int i = 1; i < ef.tv; i++)
outer_v.push_back(add_vert(sub, interp(p_w, p_u, i/(float)ef.tv)));
for(int i = 1; i < ef.tw; i++)
outer_w.push_back(add_vert(sub, interp(p_u, p_v, i/(float)ef.tw)));
outer_u.push_back(corner_w);
outer_v.push_back(corner_u);
outer_w.push_back(corner_v);
}
for(m = M-2; m > 0; m -= 2) {
vector<int> inner_u, inner_v, inner_w;
const float t0 = m / (float)M;
float2 center = make_float2(1.0f/3.0f, 1.0f/3.0f);
/* 3 corner vertices */
float2 p_u = interp(center, make_float2(1.0f, 0.0f), t0);
float2 p_v = interp(center, make_float2(0.0f, 1.0f), t0);
float2 p_w = interp(center, make_float2(0.0f, 0.0f), t0);
int corner_u = add_vert(sub, p_u);
int corner_v = add_vert(sub, p_v);
int corner_w = add_vert(sub, p_w);
/* construct array of vertex indices for each side */
inner_u.push_back(corner_v);
inner_v.push_back(corner_w);
inner_w.push_back(corner_u);
for(int i = 1; i < m; i++) {
/* add vertices between corners */
const float t1 = i / (float)m;
inner_u.push_back(add_vert(sub, interp(p_v, p_w, t1)));
inner_v.push_back(add_vert(sub, interp(p_w, p_u, t1)));
inner_w.push_back(add_vert(sub, interp(p_u, p_v, t1)));
}
inner_u.push_back(corner_w);
inner_v.push_back(corner_u);
inner_w.push_back(corner_v);
/* stitch together inner/outer with triangles */
stitch_triangles(outer_u, inner_u);
stitch_triangles(outer_v, inner_v);
stitch_triangles(outer_w, inner_w);
outer_u = inner_u;
outer_v = inner_v;
outer_w = inner_w;
}
/* fill up last part */
if(m == -1) {
/* single triangle */
add_triangle(outer_w[0], outer_u[0], outer_v[0]);
}
else {
/* center vertex + 6 triangles */
int center = add_vert(sub, make_float2(1.0f/3.0f, 1.0f/3.0f));
add_triangle(outer_w[0], outer_w[1], center);
add_triangle(outer_w[1], outer_w[2], center);
add_triangle(outer_u[0], outer_u[1], center);
add_triangle(outer_u[1], outer_u[2], center);
add_triangle(outer_v[0], outer_v[1], center);
add_triangle(outer_v[1], outer_v[2], center);
}
}
void TriangleDice::dice(SubPatch& sub, EdgeFactors& ef)
{
/* todo: handle 2 1 1 resolution */
int M = max(ef.tu, max(ef.tv, ef.tw));
reserve(ef, M);
add_grid(sub, ef, M);
assert(vert_offset == mesh->verts.size());
}
CCL_NAMESPACE_END