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connecting points using gluCylinder function

Mateusz Małczak2006-11-23comments

how to connect two points with cylinder ? drawing cylinders is very easy while using OpenGl and its quadrics. one simply call funciton gluCylinder with proper parameters. as one can read in OpenGl manual reference, this function draws cylinder along Z axis. The bottom of cylinder is placed in (X,Y,0) plane and the top of cylinder is in plane (X,Y,height). Where height is height of cylinder and is given as one of parameters. if we have two points p1=(x1,y1,z1) and p2=(x2,y2,z2) and we want to connect them with cylinder, we would like to use gluCylinder function. to do this we have to transform our coordinate system, so its Z axis coincide with direction given be vector n=p2-p1.

to do this we have to
0. remember current coordinate system
1. translate cooridinate system do point p1
2. rotate aroud Y axis, so the Z axis coincide with projection of vector n on the XY plane (we get new coorindate system X'YZ')
3. rotate around X' axis, so the Z' axis conicide with vector n direction
4. use gluCylinder function to draw cylinder with height equal |p2-p1|
5. restore saved coordinate system its easy to show that points 1-3 can be realized using single matrix, given below

transform.png

where n=p2-p1. when one calculates given matrix, we can set it as a current transformation matrix using function glLoadMatrix*.

SRTM

Mateusz Małczak2006-10-17gpscomments

dump_image.jpg
Above image shows Cracow-Częstochowa Upland, the hipsometric map shown on that image has been generated from SRTM data. SRTM-3 terrain data of Poland one can get here (page in polish only). With SRTM data it is very easy to create such a hipsometric maps and/or profiles of selected areas. As an example lets us consider the Belchatow lignite delf. In the picture shown below
dump_image1.jpg
one can see the mine (delf) on the left side of image, and on the right, one can see mine waste dump. If one create a hipsometric profile of that terrain, one will see that the difference in elevation between the lowest point (blue area) and the highest (dark orange area) is about ~ 370 meters.
Currently im working on application to create hipsometric maps (vector representation of elevation levels) directly from SRTM data, to be used with my gps unit. Application can already create hipsometric profiles along specified line, and that was the easier part...

: Heart surface :

Mateusz Małczak2006-10-11c++comments

Lets take equation

heart_eq.png
when one solve given eq one will see a... heart. so called heart surface.
heart-2.jpg heart-1.jpg
My c++ implementation using OpenGl and Glut libraries can be found here. Compiled Windows executable can be downloaded here, archive also contains glut.dll file.
The heart surface has been also used to create animated desktop friend like application. desktop friend is an animated , custom shaped, top level (always visible) window. in this case apart of animated 3d heart you have posibility of placing your own text on it. In conclusion - It doesnt do anything - but looks quite nice.
heart_app1.png

DOWNLOAD

fractal image #2 - hiperspeed mandelbrot

Mateusz Małczak2006-10-10fractalscomments

blog_mendel_2.jpg
This fractal image has been generated using a bit modified Mandelbrot technique, where the initial z is defined as
frac_eq_2.png
[read more]

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