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picker.cpp
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picker.cpp
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#include <GL/glew.h>
#include "picker.h"
using namespace std;
using namespace std::tr1;
Picker::Picker(const RigTForm& initialRbt, const ShaderState& curSS)
: drawer_(initialRbt, curSS)
, idCounter_(0)
, srgbFrameBuffer_(!g_Gl2Compatible) {}
bool Picker::visit(SgTransformNode& node) {
nodeStack_.push_back(node.shared_from_this());
return drawer_.visit(node);
}
bool Picker::postVisit(SgTransformNode& node) {
nodeStack_.pop_back();
return drawer_.postVisit(node);
}
bool Picker::visit(SgShapeNode& node) {
addToMap(++idCounter_, dynamic_pointer_cast<SgRbtNode>(nodeStack_.back()));
Cvec3 c = idToColor(idCounter_);
safe_glUniform3f(drawer_.getCurSS().h_uIdColor, c[0], c[1], c[2]);
return drawer_.visit(node);
}
bool Picker::postVisit(SgShapeNode& node) {
return drawer_.postVisit(node);
}
shared_ptr<SgRbtNode> Picker::getRbtNodeAtXY(int x, int y) {
PackedPixel image;
glReadPixels(x, y, 1, 1, GL_RGB, GL_UNSIGNED_BYTE, &image);
return find(colorToId(image));
}
//------------------
// Helper functions
//------------------
//
void Picker::addToMap(int id, shared_ptr<SgRbtNode> node) {
idToRbtNode_[id] = node;
}
shared_ptr<SgRbtNode> Picker::find(int id) {
IdToRbtNodeMap::iterator it = idToRbtNode_.find(id);
if (it != idToRbtNode_.end())
return it->second;
else
return shared_ptr<SgRbtNode>(); // set to null
}
// encode 2^4 = 16 IDs in each of R, G, B channel, for a total of 16^3 number of objects
static const int NBITS = 4, N = 1 << NBITS, MASK = N-1;
Cvec3 Picker::idToColor(int id) {
assert(id > 0 && id < N * N * N);
Cvec3 framebufferColor = Cvec3(id & MASK, (id >> NBITS) & MASK, (id >> (NBITS+NBITS)) & MASK);
framebufferColor = framebufferColor / N + Cvec3(0.5/N);
if (!srgbFrameBuffer_)
return framebufferColor;
else {
// if GL3 is used, the framebuffer will be in SRGB format, and the color we supply needs to be in linear space
Cvec3 linearColor;
for (int i = 0; i < 3; ++i) {
linearColor[i] = framebufferColor[i] <= 0.04045 ? framebufferColor[i]/12.92 : pow((framebufferColor[i] + 0.055)/1.055, 2.4);
}
return linearColor;
}
}
int Picker::colorToId(const PackedPixel& p) {
const int UNUSED_BITS = 8 - NBITS;
int id = p.r >> UNUSED_BITS;
id |= ((p.g >> UNUSED_BITS) << NBITS);
id |= ((p.b >> UNUSED_BITS) << (NBITS+NBITS));
return id;
}