/usr/share/oolite/Shaders/oolite-dust.vertex is in oolite-data 1.77.1-3.
This file is owned by root:root, with mode 0o644.
The actual contents of the file can be viewed below.
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 | /*
oolite-dust.vertex
Vertex shader for interplanetary dust.
© 2010-2013 Jens Ayton
This program is free software; you can redistribute it and/or
modify it under the terms of the GNU General Public License
as published by the Free Software Foundation; either version 2
of the License, or (at your option) any later version.
This program is distributed in the hope that it will be useful,
but WITHOUT ANY WARRANTY; without even the implied warranty of
MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the
GNU General Public License for more details.
You should have received a copy of the GNU General Public License
along with this program; if not, write to the Free Software
Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston,
MA 02110-1301, USA.
*/
/* The following macros are provided by Oolite, to ensure that they stay in
sync with the values used in non-shader mode.
#define OODUST_SCALE_MAX (float(2))
#define OODUST_SCALE_FACTOR (float(0.002))
#define OODUST_SIZE (float(2000))
*/
/* “Warpiness”: 0 for dots when not warping and the near end of lines when
warping, 1 for the far end of lines when warping. (Note that both “ends”
have the same input coordinates, and the shader applies the warp effect.)
*/
attribute float aWarpiness;
uniform vec4 uWarp;
// Player position, offset by -OODUST_SIZE/2 on each coordinate.
uniform vec4 uOffsetPlayerPosition;
varying vec4 vColor;
void main(void)
{
/* Dust particles are arranged in a cube of 2000×2000×2000 metres
(OO_DUST_SIZE) around the universe origin. The following code offsets
each particle to be somewhere in a cube of the same size around the
player, creating an infinite repeating pattern.
*/
vec4 position = mod(gl_Vertex - uOffsetPlayerPosition, OODUST_SIZE) + uOffsetPlayerPosition;
position = position - uWarp * aWarpiness;
// Project the dust, and find its distance from the camera.
position.w = 1.0;
position = gl_ModelViewProjectionMatrix * position;
gl_Position = position;
float distance = length(position);
/* The original non-shader code fades to black using linear fog, with a
near plane of 500 and a far plane of 1000.
OODUST_SCALE_MAX is far plane/near plane, and OODUST_SCALE_FACTOR
is 1.0/(far plane - near plane).
This gives us a function such that f(x) ≥ 1 when x ≤ near plane,
f(x) ≤ 0 when x ≥ far plane, and a linear ramp in between, which we
then clamp to [0..1].
*/
float alpha = clamp(OODUST_SCALE_MAX - distance * OODUST_SCALE_FACTOR, 0.0, 1.0);
vColor = vec4(gl_Color.rgb, alpha * gl_Color.a);
}
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