Selection, Name stack, Hits - Newbie question

Darjk · 2002-02-18T22:41:23

Okay, I''ve tested my code pretty thoroughly and hits and everything is working. The only thing that isn''t working is the name stack. GLint viewport[4]; double ratio; glSelectBuffer(BUFSIZE,selectBuf); glGetIntegerv(GL_VIEWPORT,viewport); glRenderMode(GL_SELECT); glInitNames(); glMatrixMode(GL_PROJECTION); glPushMatrix(); glLoadIdentity(); gluPickMatrix(mouse_x,viewport[3]-mouse_y,5,5,viewport); ratio = (viewport[2]+0.0) / viewport[3]; gluPerspective(45,ratio,0.1,1000); glMatrixMode(GL_MODELVIEW); that is more or less from a book. Next I draw ''tiles'' each with its own name using glPushName(GROUND); for ( X = 0; X < MAP_SIZE; X += STEP_SIZE ) { for ( Y = 0; Y < MAP_SIZE; Y += STEP_SIZE ) { glPushName(X*MAP_SIZE+Y); x = X; y = 0; z = Y; glColor3f(1.0f, 1.0f, 1.0f); glVertex3i(x, y, z); ...etc...etc //glPopName(); } } glEnd(); //glPopName(); Is there anything wrong with that ? As far as I can tell from the examples PopName should be used but if I use it it will erase the name on top of the stack which I don''t want (I don''t think). Now when performing to see if I have any hits, I get 1 hit, but the names in the hit are always 0. If I put glPushName(-1); during initialisation it will return 1 name but it is always -1, so why does that count during initialisation but not during rendering ? and yes I''ve set the Render mode to SELECT. Any idea''s ? thanks in advance!

Graphics and GPU Programming Programming

Started by Darjk February 18, 2002 03:08 AM

12 comments, last by Darjk 22 years, 2 months ago

Darjk

124

Author

February 18, 2002 04:13 AM

Okay I found 1 problem, I messed up a stupid PopMatrix, PushMatrix which was messing up the naming during the tile rendering.

Now it is always returning 0.

Also I tried clicking on the cornor of a tile it only returned 1 result, but I think I have an idea now!

Ill let you know how it goes in a few mins.

Edit:

Nope, still always returning 1.
I may have my tree naming setup incorrectly, either that or I'm not naming correctly for each individual tile ?

Edited by - Darjk on February 18, 2002 5:23:47 AM

Edit #2:

Okay I'm not getting these results

Hits = 1
number of names for hit = 2

z1 is 4198027884;
z2 is 4216201336

the name is -1

the name is 0

It seems to be returning the -1 is just something I push onto the name stack and the 0 is the ground, still not giving me the tile name though

Edited by - Darjk on February 18, 2002 5:29:01 AM

Fruny

1,658

February 18, 2002 04:29 AM

Honestly, I don''t know. As long as you are placing a name on the stack before drawing your primitives, that name should show up in the hit record if that primitive is rendered (within the restricted window from gluPickMatrix).

Which leads to a last test : remove the call to gluPickMatrix and let it render the whole scene... you should have N hits, where N is the total number of names you picked.

"Debugging is twice as hard as writing the code in the first place. Therefore, if you write the code as cleverly as possible, you are, by definition, not smart enough to debug it." — Brian W. Kernighan

Darjk

124

Author

February 18, 2002 04:56 AM

Okay I finally figured it out.

The way I was drawing my tiles was incorrectly and I did not pick up on it

Basically I needed to put the glBegin(QUADS); inside the For loop instead of begining, drawing all tiles, then ending it.

I now get the following results:

Hits = 4
number of names for hit = 3

z1 is 4208480774;
z2 is 4216927619

the name is -1

the name is 0

the name is 5

number of names for hit = 3

z1 is 4198754167;
z2 is 4208480774

the name is -1

the name is 0

the name is 9

number of names for hit = 3

z1 is 4208480774;
z2 is 4216927619

the name is -1

the name is 0

the name is 1029

number of names for hit = 3

z1 is 4198754167;
z2 is 4208480774

the name is -1

the name is 0

the name is 1033

Thanks for all the help and testing suggestions.. very much appreciated!

You''ll probably hear from me in a couple days trying to work out what ever comes next