Object Selection (OpenGL)
Author
Hi everyone,
I like to ask some questions about objects selection.
I know in OpenGL there is a function for selecting and picking objects in 3D, they are GL_SELECT etc..
I know they works like glInitNames((); .....and so on.
however, does this function works on objects that is loaded from other resources, such as .obj, .3ds ....etc.
Whatever is rendered between a name push and pop can be selected with that name, so it doesnt matter if it was loaded from a resource. Check out NeHe's tutorial on the subject. If you still have questions after that, feel free to ask them here.
Author
I have look at that example before, however i do still have problems.
that is how do i assign the name to individual object?
my loading code
CObjLoader object;
///////////
for(i=0; i< object.numofobjects; i++)
object.rederscene();
///////////
How do i ensure the name is assigned in each individual object?
please give me a hand.
millions of thanks
that is how do i assign the name to individual object?
my loading code
CObjLoader object;
///////////
for(i=0; i< object.numofobjects; i++)
object.rederscene();
///////////
How do i ensure the name is assigned in each individual object?
please give me a hand.
millions of thanks
Author
sorry my friend, i have another question to ask.
i can correct detect if my cursor have been hit the object. however, say if i want to click the object and then move it; in that case how would I know which object I need to change coordinates(translate), i can't just use "gltranslatef" for translating the object because I load the files into a template and collisiion detection is a part of my project.
please give me some adive on it.
Millions of thanks.
i can correct detect if my cursor have been hit the object. however, say if i want to click the object and then move it; in that case how would I know which object I need to change coordinates(translate), i can't just use "gltranslatef" for translating the object because I load the files into a template and collisiion detection is a part of my project.
please give me some adive on it.
Millions of thanks.
One way would be to add a unique identifier to each object you are going to draw. When you draw for picking purposes, use that identifier in the glPushName(). When you detect a hit, search all your objects for the one that has the matching identifier.
One word of caution. Using the GL_SELECT rendering mode on some ATI cards can have severe performance penalties. I don't know if they have addressed this issue, since it's been a few months since I've tried. I ended up switching to using unique colors for each item I want to select and reading back from the color buffer.
One word of caution. Using the GL_SELECT rendering mode on some ATI cards can have severe performance penalties. I don't know if they have addressed this issue, since it's been a few months since I've tried. I ended up switching to using unique colors for each item I want to select and reading back from the color buffer.
Author
I am Sorry to ask you again, but how do i set an identifier to each object?
the following are some codes of my program.
the following are some codes of my program.
CObjLoader object;/////////////////////object.Load(Filename);bool TRANS = FALSE;float xx=0, yy=0, zz=0;//////////////////////////////////////////for(i=0; i< object.numofobjects; i++){ if(TRANS) translate(xx, yy, zz); object.pModel->renderscene();}///////////////////////when i do translation i simply add the number to every vertices of the object.void translate(float xx, float yy, float zz){ for(int i; i< NumOfObjects; i++) { for(int j; j< object.NumOfVertice; j++) { object.pModel->pVerts[j].x += xx; object.pModel->pVerts[j].y += yy; object.pModel->pVerts[j].z += zz; } } }
Author
if you want more codes to show, welcome to ask, but please give me some more advices and direction.
thanks
thanks
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