Hi,
I get a vertex array for handling my data.
There are ten numbers in my array:
{ 4.11196e+006 -156404 0.000000
4.11631e+006 -156406 0.000000
4.11631e+006 156.249 0.000000
4.11196e+006 156.249 0.000000
4.11601e+006 -152445 -1.80000
4.11620e+006 -155162 -12.8000
4.11596e+006 -152238 -1.50000
4.11597e+006 -152368 -1.20000
4.11585e+006 -150986 -3.00000
4.11600e+006 -152979 -4.80000
}
I tried to use those data. However, I won’t able to see anything on the screen. I use the following code to do the drawing
glNewList(1, GL_COMPILE);
//Where objects should draw, etc…
glTranslatef(0.0f,0.0f,-10.0f);
glBegin(GL_QUADS); glColor3f(1.0f,0.0f,0.0f);
for( int i = 0; i < 10; i++ ) {
glVertex3f( (float)(tempVertexArray[i].x), (float)(tempVertexArray[i].y), (float)(tempVertexArray[i].z) );
}
glEnd();
glEndList();
Thank you for any help
Originally posted by beachboy1976:
[b]Hi,
I get a vertex array for handling my data.
There are ten numbers in my array:
{ 4.11196e+006 -156404 0.000000
4.11631e+006 -156406 0.000000
4.11631e+006 156.249 0.000000
4.11196e+006 156.249 0.000000
4.11601e+006 -152445 -1.80000
4.11620e+006 -155162 -12.8000
4.11596e+006 -152238 -1.50000
4.11597e+006 -152368 -1.20000
4.11585e+006 -150986 -3.00000
4.11600e+006 -152979 -4.80000
}
I tried to use those data. However, I won’t able to see anything on the screen. I use the following code to do the drawing
glNewList(1, GL_COMPILE);
//Where objects should draw, etc…
glTranslatef(0.0f,0.0f,-10.0f);
glBegin(GL_QUADS); glColor3f(1.0f,0.0f,0.0f);
for( int i = 0; i < 10; i++ ) {
glVertex3f( (float)(tempVertexArray[i].x), (float)(tempVertexArray[i].y), (float)(tempVertexArray[i].z) );
}
glEnd();
glEndList();
Thank you for any help[/b]
First of all, your are drawing quads.
That means the first 4 vertices will form a quad, next four vertices will form another quad. The last two vertices in your list of ten vertices will be ignored by OpenGL.
Also, OpenGL assumes 4 vertices lie on a plane, otherwise the result is undefined.
Thirdly, you don’t draw things with this code. You only compile a list of comands to be called later on. You need to call glCallLists(…) to execute the stuff in your list.
Hope it helps,
Coconut
[This message has been edited by Coconut (edited 03-22-2002).]
I am totally a beginner to OpenGL. Based on the data I have, how can I draw something on the screen, such as triangles, or quads.
Thank you for helping me
Originally posted by Coconut:
[b] First of all, your are drawing quads.
That means the first 4 vertices will form a quad, next four vertices will form another quad. The last two vertices in your list of ten vertices will be ignored by OpenGL.
Also, OpenGL assumes 4 vertices lie on a plane, otherwise the result is undefined.
Thirdly, you don’t draw things with this code. You only compile a list of comands to be called later on. You need to call glCallLists(…) to execute the stuff in your list.
Hope it helps,
Coconut
[This message has been edited by Coconut (edited 03-22-2002).][/b]
glCallList(<ListID> ) after creating the list. In your case <ListID> = 1. Alternatively, use the code you had without the List condstructors.
First of all, what kind of data you have?
The order of vertices in the array you pass to OpenGL will affect the result.
Your geometry coordinates are faaaaaaar out there.
I know. However, I don’t have any option. Those data have been set by the client. I have to make a mesh based on those data.
If there any way I can do this?
Originally posted by zeckensack:
Your geometry coordinates are faaaaaaar out there.
The data was created based on logitude and latitude of earth. I have to use those data to create a mesh to show the client.
Please help me out with this. Is there any way I can use those data to draw a mesh?
Originally posted by Coconut:
First of all, what kind of data you have?
The order of vertices in the array you pass to OpenGL will affect the result.
I will use a simple example:
Let’s say we have four vertices P1, P2, P3 and P4.
Passing the array of {P1, P2, P3, P4} will be different from {P1, P2, P4, P3}.
Can you understand this?
Yes Coconut.
What do we do next?
Originally posted by Coconut:
[b]I will use a simple example:
Let’s say we have four vertices P1, P2, P3 and P4.
Passing the array of {P1, P2, P3, P4} will be different from {P1, P2, P4, P3}.
Can you understand this?
[/b]
Hey BeachBoy,
Looking for someone to teach you OpenGL via this forum is not going to work. More effective would be to get a book and/or go through some tutorials.
Try this URL: http://www.opengl.org/developers/code/tutorials.html
That means you cannnot only have a list of vertices of arbitrary order. You need information at a higher level. For example, a list of triangles.
If what you have is just a list of vertices of arbitrary order, you have to build triangle list from those vertices.
In this case, you may want to read about “triangulation”, “surface reconstruction”.