🔒 Locked

Heightmaps...

Started by Noods Jul 12, 2004 at 8:08 PM 7 replies 1.2k views

Original Post

Jul 12, 2004 at 8:08 PM

Im getting ready to start working with heightmaps, and I wanted to ask a couple questions. joanusdmentia explained in another post that 2 dimensional arrays are used to create a plane, with the actual value representing the height at each point. With this in mind, how would you sort through the 2D array to break the points up into triangles? I have seen higher detail heightmaps break arrays up into more complex patterns of triangles, but Im just looking to find how to break up a simple array.

nts

115

nts

Jul 12, 2004 at 10:49 PM

Hope this is what your looking for

consider your array 4x2 in this case but u can apply to any other sizes (should be even)

You have the points as follows and from the points 0,1,4,5 you can construct 2 triangles (forming a quad). The math behind this is pretty easy.

[0]-[1] [2] [3] | \ |[4]-[5] [6] [7]Triangle1_point0.y = array[offset_x + 0][offset_y + 0] ->index[0]Triangle1_point1.y = array[offset_x + 0][offset_y + 1] ->index[4]Triangle1_point2.y = array[offset_x + 1][offset_y + 1] ->index[5].. triangle 2 here

That will generate the first triangles y coordinates for you (assuming your array stores the y coords for the map) to get the x and z simply use the offset_x and offset_y's and to generate the rest of the triangles just move the offsets along. I suggest you generate 2 triangles at a time (forming a quad) then you can simply write one nested loop to generate all the data for you.

Hope that helped, hope I didn't make a mistake :) (used to working in 1d arrays :)

no one

Jul 12, 2004 at 10:52 PM

go Here

There are 4 tutorials going from very basic to detail texturing and fogging.

Good luck and have fun.
~Jason

GameOxygen

Jul 12, 2004 at 11:58 PM

You also have to think about the ordering of the vertices in a triangle.

if you plan to uee direct3d, the vertices should be ordered clockwise, if you plan to use opengl, the vertices should be ordered anti-clockwise.

ngill

Jul 13, 2004 at 12:22 AM

you can easily change the front face of the triangles in OpenGL by using the

glFrontFace(GL_CW); //or GL_CCW

function call.

Quote:
Original post by GameOxygen
You also have to think about the ordering of the vertices in a triangle.

if you plan to uee direct3d, the vertices should be ordered clockwise, if you plan to use opengl, the vertices should be ordered anti-clockwise.

GameOxygen

Jul 13, 2004 at 2:03 AM

Ok, I was thinking if he wanted to use triangle strips to render the terrain. The ordering of the vertices should be a little different when comparing opengl to direct3d?

Roquqkie

Jul 13, 2004 at 2:21 AM

Quote:
Original post by GameOxygen
Ok, I was thinking if he wanted to use triangle strips to render the terrain. The ordering of the vertices should be a little different when comparing opengl to direct3d?

No...

MGB

Jul 13, 2004 at 6:13 AM

Quote:
Original post by ngill
you can easily change the front face of the triangles in OpenGL by using the glFrontFace() function.

But if you use this and then come to need consistent face winding then you have some rework to do, so generally be consistent with your winding and don't use this function.

python_regious

103

python_regious

Jul 13, 2004 at 10:34 AM

Quote:
Original post by Aph3x
Quote:
Original post by ngill
you can easily change the front face of the triangles in OpenGL by using the glFrontFace() function.

But if you use this and then come to need consistent face winding then you have some rework to do, so generally be consistent with your winding and don't use this function.

Yes, you should be consistent, but this function allows you to be consistent in both ways.

Topic Locked

This topic has been locked by a moderator. New replies are not allowed.