Mesh display.

Ok, so I managed to copy the data into a 2D array. Yet when I use the algorithm on page 269 I get a cross section of the mesh and my computer just hangs and refreshes after a while with the same image.When I sample the data, the cross section becomes even more jagged.

I am currently using myinit() with

Language: C++
glOrtho(0.0, 50.0, 0.0, 50.0, -50.0, 50.0);

inside of it.

I have also tried using this function instead of myinit()

Language: C++
void myReshape(int w, int h)
{
    glViewport(0, 0, w, h);
    glMatrixMode(GL_PROJECTION);
    glLoadIdentity();
    if (w <= h) 
	glOrtho (-50.0, 50.0, -50.0*(GLfloat)h/(GLfloat)w, 
	    50.0*(GLfloat)h/(GLfloat)w, -50.0, 50.0);
    else 
	glOrtho (-50.0*(GLfloat)w/(GLfloat)h, 
	    50.0*(GLfloat)w/(GLfloat)h, -50.0, 50.0, -50.0, 50.0);
    glMatrixMode(GL_MODELVIEW);
    glLoadIdentity ();
}

Using my reshape causes nothing to be displayed.
Have tired a small 5x5 array with lower numbers and it works fine on both functions.

Am I missing anything? Been struggling with this for a week now,
Any help / advice welcome

Thanks,
Benjamin Prevenhueber

Hanging problem has been solved by sampling.cpp that has been uploaded onto MyUnisa.

After a week of pulling my hair out, I finally have a mesh of Honolulu

iv been using the same ortho and myinit and getting a distorted mesh...still pulling my hair

im not sure how to scale...where about must i look to find info on that...thanx

jen8, I'd say you should look to scale in the sampling code that was given us. I did mine there, untill I found my mesh looking normal.

_______________________________________
Don't be different...be the one making a difference

BlaXpydo Wrote:
-------------------------------------------------------
> jen8, I'd say you should look to scale in the
> sampling code that was given us. I did mine there,
> untill I found my mesh looking normal.

Just devide the ypt by an integer value before you store it.

jen8 Wrote:
-------------------------------------------------------
> iv been using the same ortho and myinit and

Asked the lecturer a week ago about glOrth version of myReshape and he said we should use the one on page 267, which uses a glFrustum.
Just change the last value (20.0) to (200.0) in both the if and else parts, to get a bigger volume.
See if that helps.

> getting a distorted mesh...still pulling my hair

thank you soooooooo much for all your help i finally completed this assignment... ...the scaling did help.i divided the y by 0.01

You're welcome.
Glad I could help.

BenVP

What options did you use to make the lines not get drawn in front of the meshes?

My current program at the moment looks almost exactly the same then yours but I can see my GL_LINE_LOOP lines that should be behind the mountain any insight would be appreciated.

>but I can see my GL_LINE_LOOP lines that should be behind the mountain
when does this occur?

Things to look out for:
Have you used the polygon offset code on page 269?
Is it in the right order? gl_quads then gl_line_loop
How are you viewing the object? + / - z?
What angle of view are you using?

BenVP Wrote:
-------------------------------------------------------
> >but I can see my GL_LINE_LOOP lines that should
> be behind the mountain
> when does this occur?
>
> Things to look out for:
> Have you used the polygon offset code on page
> 269?

You mean:

glEnable(GL_POLYGON_OFFSET_LINE);
glPolygonOffset(1.0, 0.5);

as you init your application or:

glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);

as you reshape your viewport? Sorry I'm using the Fourth Edition of the prescribed book.


> Is it in the right order? gl_quads then
> gl_line_loop

Yes

> How are you viewing the object? + / - z?

using glFrustum with a +2.0 on z.

> What angle of view are you using?

I'm using gluLookAt(viewer[0],viewer[1],viewer[2], 5.0, 0.0, 5.0, 0.0, 1.0, 0.0);

So to see my problem here is a image:



Is it cheating to enable GL_DEPTH_TEST?

Thanks,

d-_-b Wrote:
-------------------------------------------------------
> BenVP Wrote:
> --------------------------------------------------
> -----
> > >but I can see my GL_LINE_LOOP lines that
> should
> > be behind the mountain
> > when does this occur?
> >
> > Things to look out for:
> > Have you used the polygon offset code on page
> > 269?
>
> You mean:
>

I meant did you use the code segment

Language: C++
          glColor3f(1.0, 1.0, 1.0);
          glBegin(GL_QUADS);
            glVertex3i(i,y[i][j],j);
            glVertex3i(i+1,y[i+1][j],j);
            glVertex3i(i+1,y[i+1][j+1],j+1);
            glVertex3i(i,y[i][j+1],j+1);
          glEnd();
 
          glColor3f(0.0, 0.0, 0.0);
          glBegin(GL_LINE_LOOP);
            glVertex3i(i,y[i][j],j);
            glVertex3i(i+1,y[i+1][j],j);
            glVertex3i(i+1,y[i+1][j+1],j+1);
            glVertex3i(i,y[i][j+1],j+1);
          glEnd();

> glEnable(GL_POLYGON_OFFSET_LINE);
> glPolygonOffset(1.0, 0.5);

Never used this. ^
Not meant to be used.

>
> as you init your application or:
>
> glMatrixMode(GL_PROJECTION);
> glLoadIdentity();
> glOrtho(-1.0, 1.0, -1.0, 1.0, -1.0, 1.0);
>
> as you reshape your viewport? Sorry I'm using the
> Fourth Edition of the prescribed book.

I don't think the book editions are that different.
I could be wrong.

>
>
> > Is it in the right order? gl_quads then
> > gl_line_loop
>
> Yes
>
> > How are you viewing the object? + / - z?
>
> using glFrustum with a +2.0 on z.

Try zooming out more to see what happens.

>
> > What angle of view are you using?
>
> I'm using gluLookAt(viewer[0],viewer[1],viewer[2],
> 5.0, 0.0, 5.0, 0.0, 1.0, 0.0);
>
> So to see my problem here is a image:
>
> http://i.imgur.com/0kqvS.jpg
>
> Is it cheating to enable GL_DEPTH_TEST?

This just makes the mesh look fragmented,
it looks better without it. Not meant to be used.

>
> Thanks,

Ok, been working on the assignment this week...all seems fine, but I'm not happy with my mesh. Too linear. Why could that be?

_______________________________________
Don't be different...be the one making a difference

Thanks for the feedback BenVP!

I was a idiot:

I created a function called DrawHeightMap(bool wireframe) where I first draw all the quads and then the lines and that created the "see through" effect as in the image I posted earlier.

Kind Regards,

You're welcome.

Hi guys,

I having trouble with the drawing of the mesh, everything looks OK at the start,
as you can see where I made the arrow the back lines, are at the back of the mountain where they should be.

But now when I zoom in on the small bump in the rectangle area, it looks fine...

until I rotate around it a bit...

Is there any trick or something I can use to get around that?
I used the code on page 296, but that did not solve this problem.

Thanks
Rotti

hello could you please help me,i dont know what to do with these honolulu sample digits

blv

BenVP Wrote:
-------------------------------------------------------
> Hanging problem has been solved by sampling.cpp
> that has been uploaded onto MyUnisa.

Hi, from the name of this .cpp file and the screenshots I've seen, I suspect this might be similar to my solution from some years ago: http://dl.dropbox.com/u/3038174/cos340%20ass2.pdf

I'd greatly appreciate it if you could post the code here or mail it to me at thomas.ludwig@gmail.com, thanks