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
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
|
/**
* @file WLCloudsV.glsl
*
* $LicenseInfo:firstyear=2005&license=viewerlgpl$
* Second Life Viewer Source Code
* Copyright (C) 2005, Linden Research, Inc.
*
* This library is free software; you can redistribute it and/or
* modify it under the terms of the GNU Lesser General Public
* License as published by the Free Software Foundation;
* version 2.1 of the License only.
*
* This library 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
* Lesser General Public License for more details.
*
* You should have received a copy of the GNU Lesser General Public
* License along with this library; if not, write to the Free Software
* Foundation, Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301 USA
*
* Linden Research, Inc., 945 Battery Street, San Francisco, CA 94111 USA
* $/LicenseInfo$
*/
uniform mat4 modelview_projection_matrix;
ATTRIBUTE vec3 position;
ATTRIBUTE vec2 texcoord0;
//////////////////////////////////////////////////////////////////////////
// The vertex shader for creating the atmospheric sky
///////////////////////////////////////////////////////////////////////////////
// Output parameters
VARYING vec4 vary_CloudColorSun;
VARYING vec4 vary_CloudColorAmbient;
VARYING float vary_CloudDensity;
VARYING vec2 vary_texcoord0;
VARYING vec2 vary_texcoord1;
VARYING vec2 vary_texcoord2;
VARYING vec2 vary_texcoord3;
VARYING float altitude_blend_factor;
// Inputs
uniform vec3 camPosLocal;
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 moonlight_color;
uniform int sun_up_factor;
uniform vec4 ambient;
uniform vec4 blue_horizon;
uniform vec4 blue_density;
uniform float haze_horizon;
uniform float haze_density;
uniform float cloud_shadow;
uniform float density_multiplier;
uniform float max_y;
uniform vec4 glow;
uniform float sun_moon_glow_factor;
uniform vec4 cloud_color;
uniform float cloud_scale;
void main()
{
// World / view / projection
gl_Position = modelview_projection_matrix * vec4(position.xyz, 1.0);
vary_texcoord0 = texcoord0;
// Get relative position
vec3 P = position.xyz - camPosLocal.xyz + vec3(0,50,0);
// fade clouds beyond a certain point so the bottom of the sky dome doesn't look silly at high altitude
altitude_blend_factor = (P.y > -4096.0) ? 1.0 : 1.0 - clamp(abs(P.y) / max_y, 0.0, 1.0);
// Set altitude
if (P.y > 0.)
{
P *= (max_y / P.y);
}
else
{
P *= (-32000. / P.y);
}
// Can normalize then
vec3 Pn = normalize(P);
float Plen = length(P);
// Initialize temp variables
vec4 temp1 = vec4(0.);
vec4 temp2 = vec4(0.);
vec4 blue_weight;
vec4 haze_weight;
vec4 sunlight = (sun_up_factor == 1) ? sunlight_color : moonlight_color;
vec4 light_atten;
// Sunlight attenuation effect (hue and brightness) due to atmosphere
// this is used later for sunlight modulation at various altitudes
light_atten = (blue_density + vec4(haze_density * 0.25)) * (density_multiplier * max_y);
// Calculate relative weights
temp1 = blue_density + haze_density;
blue_weight = blue_density / temp1;
haze_weight = haze_density / temp1;
// Compute sunlight from P & lightnorm (for long rays like sky)
temp2.y = max(0., max(0., Pn.y) * 1.0 + lightnorm.y );
temp2.y = 1. / temp2.y;
sunlight *= exp( - light_atten * temp2.y);
// Distance
temp2.z = Plen * density_multiplier;
// Transparency (-> temp1)
// ATI Bugfix -- can't store temp1*temp2.z in a variable because the ati
// compiler gets confused.
temp1 = exp(-temp1 * temp2.z);
// Compute haze glow
temp2.x = dot(Pn, lightnorm.xyz);
temp2.x = 1. - temp2.x;
// temp2.x is 0 at the sun and increases away from sun
temp2.x = max(temp2.x, .001);
// Set a minimum "angle" (smaller glow.y allows tighter, brighter hotspot)
temp2.x *= glow.x;
// Higher glow.x gives dimmer glow (because next step is 1 / "angle")
temp2.x = pow(temp2.x, glow.z);
// glow.z should be negative, so we're doing a sort of (1 / "angle") function
temp2.x *= sun_moon_glow_factor;
// Add "minimum anti-solar illumination"
temp2.x += .25;
// Increase ambient when there are more clouds
vec4 tmpAmbient = ambient;
tmpAmbient += (1. - tmpAmbient) * cloud_shadow * 0.5;
// Dim sunlight by cloud shadow percentage
sunlight *= (1. - cloud_shadow);
// Haze color below cloud
vec4 additiveColorBelowCloud = ( blue_horizon * blue_weight * (sunlight + tmpAmbient)
+ (haze_horizon * haze_weight) * (sunlight * temp2.x + tmpAmbient)
);
// CLOUDS
sunlight = sunlight_color;
temp2.y = max(0., lightnorm.y * 2.);
temp2.y = 1. / temp2.y;
sunlight *= exp( - light_atten * temp2.y);
// Cloud color out
vary_CloudColorSun = (sunlight * temp2.x) * cloud_color;
vary_CloudColorAmbient = tmpAmbient * cloud_color;
// Attenuate cloud color by atmosphere
temp1 = sqrt(temp1); //less atmos opacity (more transparency) below clouds
vary_CloudColorSun *= temp1;
vary_CloudColorAmbient *= temp1;
vec4 oHazeColorBelowCloud = additiveColorBelowCloud * (1. - temp1);
// Make a nice cloud density based on the cloud_shadow value that was passed in.
vary_CloudDensity = 2. * (cloud_shadow - 0.25);
// Texture coords
vary_texcoord0 = texcoord0;
vary_texcoord0.xy -= 0.5;
vary_texcoord0.xy /= max(0.001, cloud_scale);
vary_texcoord0.xy += 0.5;
vary_texcoord1 = vary_texcoord0;
vary_texcoord1.x += lightnorm.x * 0.0125;
vary_texcoord1.y += lightnorm.z * 0.0125;
vary_texcoord2 = vary_texcoord0 * 16.;
vary_texcoord3 = vary_texcoord1 * 16.;
// Combine these to minimize register use
vary_CloudColorAmbient += oHazeColorBelowCloud;
// needs this to compile on mac
//vary_AtmosAttenuation = vec3(0.0,0.0,0.0);
// END CLOUDS
}
|
