// ----------------------------------------------------------------------------
// Generates a opacity map from the transfer function specification
// ----------------------------------------------------------------------------
void mapOpacity(Image3D<float> & map, std::list<std::shared_ptr<Node>> transfer)
{
float samples = static_cast<float>(map.width()) - 1;
auto buffer = map.data();
memset(buffer, 0, map.size()*sizeof(float));
auto iter = transfer.begin();
auto curr = *iter;
iter++;
while (iter != transfer.end())
{
auto next = *iter;
size_t x1 = static_cast<size_t>(curr->density * samples);
if (x1 >= map.width()) x1 = map.width()-1;
size_t x2 = static_cast<size_t>(next->density * samples);
if (x2 >= map.width()) x2 = map.width()-1;
float y1 = curr->material->opticalThickness;
float y2 = next->material->opticalThickness;
for (size_t i = x1; i <= x2; i++)
{
float px = i / samples - curr->density;
float py = next->density - curr->density;
float part = low( high(px / py, 0.0f), 1.0f );
buffer[i] = - logf( 1.f - (1.f - part) * y1 - part * y2 );
}
curr = next;
iter++;
}
}
// ----------------------------------------------------------------------------
// Generates a diffuse map from the transfer function specification
// ----------------------------------------------------------------------------
void mapSpecular(Image3D<Vector<UInt8,4>> & map, std::list<std::shared_ptr<Node>> transfer)
{
float samples = static_cast<float>(map.width()) - 1;
auto buffer = map.data();
memset(buffer, 0, map.size()*sizeof(Vector<UInt8,4>));
auto iter = transfer.begin();
auto curr = *iter;
iter++;
while (iter != transfer.end())
{
auto next = *iter;
size_t x1 = static_cast<size_t>(curr->density * samples);
if (x1 >= map.width()) x1 = map.width()-1;
size_t x2 = static_cast<size_t>(next->density * samples);
if (x2 >= map.width()) x2 = map.width()-1;
Vector3f s1(curr->material->specular);
Vector3f s2(next->material->specular);
Vector4f y1(s1[0], s1[1], s1[2], curr->material->glossiness*255.0f);
Vector4f y2(s2[0], s2[1], s2[2], next->material->glossiness*255.0f);
for (size_t i = x1; i <= x2; i++)
{
float px = i / samples - curr->density;
float py = next->density - curr->density;
float part = low( high(px / py, 0.0f), 1.0f );
buffer[i] = static_cast<Vector<UInt8,4>>(y1*(1.f - part) + y2*part);
}
curr = next;
iter++;
}
}
// ----------------------------------------------------------------------------
// Generates an emissive map from the tranfer specification
// ----------------------------------------------------------------------------
void mapEmissive(Image3D<Vector4f> & map, std::list<std::shared_ptr<Node>> transfer)
{
float samples = static_cast<float>(map.width()) - 1;
auto buffer = map.data();
memset(buffer, 0, map.size()*sizeof(Vector4f));
auto iter = transfer.begin();
auto curr = *iter;
iter++;
while (iter != transfer.end())
{
auto next = *iter;
size_t x1 = static_cast<size_t>(curr->density * samples);
if (x1 >= map.width()) x1 = map.width()-1;
size_t x2 = static_cast<size_t>(next->density * samples);
if (x2 >= map.width()) x2 = map.width()-1;
Vector3f s1 = Vector3f(curr->material->emissive) / 255.0f * curr->material->emissiveStrength;
Vector3f s2 = Vector3f(next->material->emissive) / 255.0f * curr->material->emissiveStrength;
Vector4f y1(s1[0], s1[1], s1[2], 0.0f);
Vector4f y2(s2[0], s2[1], s2[2], 0.0f);
for (size_t i = x1; i <= x2; i++)
{
float px = i / samples - curr->density;
float py = next->density - curr->density;
float part = low( high(px / py, 0.0f), 1.0f );
buffer[i] = y1*(1.f - part) + y2*part;
}
curr = next;
iter++;
}
}
