How do I make a water effect view with openGLES on the iPhone?

Question

I found this vid: http://www.youtube.com/watch?v=eVi6ThY3LRs I wonder if that's some kind of standard effect of openGLES. I'm pretty sure it is, since I have seen this pretty often. KoiPond uses it, DuckDuckDuck uses it. A lot of games use it. They're not all astronauts. They're normal programmers ;) So how is this done? Is there any tutorial for this on the web?

Answer 1

(off the top of my head) Maybe a mesh distortion where the texture is pinned to the vertices and hence appears to ripple as the mesh vertices are moved? By moving a set of vertex displacements around the mesh you could make a uniform ripple like a wavefront...

Answer 2

For an old example have a look at the 'distort' example @ SGI (before it disappears). Note that this is a thing created back in 1992 (just looked in distort.c).

Awesome program that causes ripples in the image wherever the mouse button is pressed. Another mode of the program acts like a sheet of rubber and can be pulled by dragging the mouse.

I managed to compile the example on my mac.

• Rename all #include <GL/glut.h> to #include <GLUT/glut.h>
• Add a usleep(33*1000); in the idle() function
• Rename the file ripple_precalc.c to ripple_precalc.c.org (or just rm it)
• Compile with "cc *.c -framework GLUT -framework OpenGL" will create an a.out

Answer 3

JeeBee has it right. You can base your code off this tutorial:

http://www.gamedev.net/reference/articles/article915.asp

Answer 4

Hey can anyone show how to port the mesh, warp, distort, ripple, and rubber demos from SGI to the iPhone platform? I got it working in XCode on the MacOS using GLUT but I'm not quite sure how to make the conversion from OpenGL to OpenGL ES.