Picking 3D models

Guys i really need your help, any ideas on how i could get picking working in my program...i have 6 models rendered. i tried to implement picking but what happens is that, it only gets a hit when certain parts in the scene are clicked (but does not record a hit when the models are clicked). please what could be the problem.


thank you.

Please can someone help???i have read every article on picking and still cant get my program to pick properly....just a look at what i may be doing wrong will be fine thank you


void selection(int x, int y)
{
GLuint buff[64] = {0};
GLint hits, view[4];



glSelectBuffer(64, buff); //This chooses the buffer where store the values for the selection data

glGetIntegerv(GL_VIEWPORT, view); //This retrieve info about the viewport

glRenderMode(GL_SELECT); // Switching in selecton mode

glInitNames();// Clearing the name's stack

glPushName(0); //filling the stack with one element


glMatrixMode(GL_PROJECTION); // Now modify the vieving volume, restricting selection area around the cursor
glPushMatrix();
glLoadIdentity();


gluPickMatrix((GLdouble)x,(GLdouble) (view[3] - y),1.0,1.0, view); //restrict the draw to an area around the cursor
gluPerspective(45.0f,(GLfloat)screen_width/(GLfloat)screen_height,10.0f,10000.0f);

glMatrixMode(GL_MODELVIEW); // Draw the objects onto the screen

glutSwapBuffers(); //draw only the names in the stack, and fill the array

drawReflector(GL_SELECT);
//drawMast(GL_SELECT);
drawReflector(GL_SELECT);

glMatrixMode(GL_PROJECTION);
glPopMatrix();

/*
this will help us get the number of objects drawed in that area
and return to render mode
*/
hits = glRenderMode(GL_RENDER);

list_hits(hits, buff); // Print a list of the objects


//selectAll(hits, buff);

glMatrixMode(GL_MODELVIEW);
}



[quote name='GottiJay' timestamp='1309813789' post='4831146']
Guys i really need your help, any ideas on how i could get picking working in my program...i have 6 models rendered. i tried to implement picking but what happens is that, it only gets a hit when certain parts in the scene are clicked (but does not record a hit when the models are clicked). please what could be the problem.


thank you.

Please can someone help???i have read every article on picking and still cant get my program to pick properly....just a look at what i may be doing wrong will be fine thank you


void selection(int x, int y)
{
GLuint buff[64] = {0};
GLint hits, view[4];



glSelectBuffer(64, buff); //This chooses the buffer where store the values for the selection data

glGetIntegerv(GL_VIEWPORT, view); //This retrieve info about the viewport

glRenderMode(GL_SELECT); // Switching in selecton mode

glInitNames();// Clearing the name's stack

glPushName(0); //filling the stack with one element


glMatrixMode(GL_PROJECTION); // Now modify the vieving volume, restricting selection area around the cursor
glPushMatrix();
glLoadIdentity();


gluPickMatrix((GLdouble)x,(GLdouble) (view[3] - y),1.0,1.0, view); //restrict the draw to an area around the cursor
gluPerspective(45.0f,(GLfloat)screen_width/(GLfloat)screen_height,10.0f,10000.0f);

glMatrixMode(GL_MODELVIEW); // Draw the objects onto the screen

glutSwapBuffers(); //draw only the names in the stack, and fill the array

drawReflector(GL_SELECT);
//drawMast(GL_SELECT);
drawReflector(GL_SELECT);

glMatrixMode(GL_PROJECTION);
glPopMatrix();

/*
this will help us get the number of objects drawed in that area
and return to render mode
*/
hits = glRenderMode(GL_RENDER);

list_hits(hits, buff); // Print a list of the objects


//selectAll(hits, buff);

glMatrixMode(GL_MODELVIEW);
}


[/quote]

Try and reduce your far plane, from what I understand the picking will only differentiate between things more than (10000.0f /65,000) = about 0.2?. Perhaps that will help.


Here is my picking code if that helps
const int pickBufferSize = 1000;

unsigned int pickBuffer[pickBufferSize];

for ( int i = 0; i < pickBufferSize; ++i)
pickBuffer = 0;

int viewport[4];

//setup selection buffer
glSelectBuffer(pickBufferSize, pickBuffer);

glRenderMode(GL_SELECT);

//This is currently test code:
glInitNames();
glPushName(6666666); //evil!

//Set the picking matrix
glGetIntegerv(GL_VIEWPORT,viewport);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluPickMatrix(GameCore::App()->MouseX(),viewport[3]-GameCore::App()->MouseY(),
1,1,viewport);

//Normal render
this->Render();

int nHits = glRenderMode(GL_RENDER);

glMatrixMode(GL_PROJECTION);
glPopMatrix();
glLoadIdentity();


[quote name='GottiJay' timestamp='1309850396' post='4831238']
[quote name='GottiJay' timestamp='1309813789' post='4831146']
Guys i really need your help, any ideas on how i could get picking working in my program...i have 6 models rendered. i tried to implement picking but what happens is that, it only gets a hit when certain parts in the scene are clicked (but does not record a hit when the models are clicked). please what could be the problem.


thank you.

Please can someone help???i have read every article on picking and still cant get my program to pick properly....just a look at what i may be doing wrong will be fine thank you


void selection(int x, int y)
{
GLuint buff[64] = {0};
GLint hits, view[4];



glSelectBuffer(64, buff); //This chooses the buffer where store the values for the selection data

glGetIntegerv(GL_VIEWPORT, view); //This retrieve info about the viewport

glRenderMode(GL_SELECT); // Switching in selecton mode

glInitNames();// Clearing the name's stack

glPushName(0); //filling the stack with one element


glMatrixMode(GL_PROJECTION); // Now modify the vieving volume, restricting selection area around the cursor
glPushMatrix();
glLoadIdentity();


gluPickMatrix((GLdouble)x,(GLdouble) (view[3] - y),1.0,1.0, view); //restrict the draw to an area around the cursor
gluPerspective(45.0f,(GLfloat)screen_width/(GLfloat)screen_height,10.0f,10000.0f);

glMatrixMode(GL_MODELVIEW); // Draw the objects onto the screen

glutSwapBuffers(); //draw only the names in the stack, and fill the array

drawReflector(GL_SELECT);
//drawMast(GL_SELECT);
drawReflector(GL_SELECT);

glMatrixMode(GL_PROJECTION);
glPopMatrix();

/*
this will help us get the number of objects drawed in that area
and return to render mode
*/
hits = glRenderMode(GL_RENDER);

list_hits(hits, buff); // Print a list of the objects


//selectAll(hits, buff);

glMatrixMode(GL_MODELVIEW);
}


[/quote]

Try and reduce your far plane, from what I understand the picking will only differentiate between things more than (10000.0f /65,000) = about 0.2?. Perhaps that will help.


Here is my picking code if that helps
const int pickBufferSize = 1000;

unsigned int pickBuffer[pickBufferSize];

for ( int i = 0; i < pickBufferSize; ++i)
pickBuffer = 0;

int viewport[4];

//setup selection buffer
glSelectBuffer(pickBufferSize, pickBuffer);

glRenderMode(GL_SELECT);

//This is currently test code:
glInitNames();
glPushName(6666666); //evil!

//Set the picking matrix
glGetIntegerv(GL_VIEWPORT,viewport);
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
gluPickMatrix(GameCore::App()->MouseX(),viewport[3]-GameCore::App()->MouseY(),
1,1,viewport);

//Normal render
this->Render();

int nHits = glRenderMode(GL_RENDER);

glMatrixMode(GL_PROJECTION);
glPopMatrix();
glLoadIdentity();



[/quote]
thanks antoo for trying to help...i managed to get it working some days back....i appreciate
not to be greedy or anything i do need your help in some other context,i have been trying drag the models i pick in x,y and z axis, could you please explain to me how you did do this in your program...or you could give an idea how i could do this.....

thank you