1#version 120
2
3uniform sampler2D baseTexture;
4uniform float scattering;
5
6varying float fogFactor;
7varying float mie_frag;
8varying float mie_frag_mod;
9varying float z_pos;
10varying float bottom_shade;
11
12varying vec3 internal_pos;
13varying vec3 hazeColor;
14
15vec3 filter_combined (in vec3 color) ;
16
17void main(void)
18{
19      vec4 base = texture2D( baseTexture, gl_TexCoord[0].st);
20      if (base.a < 0.02)
21        discard;
22
23      float mie_factor = 0.0;
24      float geo_factor = 1.0;
25
26	  float mie_sign = 1.0;
27	  if (mie_frag < 0.0) {mie_sign = -1.0;}
28
29	  if (mie_sign > 0.0)
30		{mie_factor = smoothstep(0.8, 1.0, mie_frag);}
31	  else
32 		{mie_factor = -1.0 * (1.0 - smoothstep(-1.0, -0.8, mie_frag));}
33
34	      mie_factor *= mie_frag_mod;
35
36	//  suppress effect in cloud center
37
38	  float z_bias = 0.2 * (1.0 - smoothstep(2.0, 3.0, z_pos));
39
40	  geo_factor *= smoothstep(-0.9 - z_bias, -0.4 - z_bias, internal_pos.x) * (1.0 -smoothstep(0.4 + z_bias, 0.9 + z_bias, internal_pos.x));
41	  geo_factor *= smoothstep(-0.9 - z_bias, -0.4 - z_bias, internal_pos.y) * (1.0 -smoothstep(0.4 + z_bias, 0.9 + z_bias, internal_pos.y));
42	  geo_factor *= smoothstep(0, 0.3, internal_pos.z) * (1.0 - smoothstep(0.5, 1.2, internal_pos.z));
43
44	 if (mie_sign > 0.0)
45		{
46		mie_factor *=(1.0 -geo_factor);
47		}
48
49		float transparency = smoothstep(0.0, 0.7, base.a);
50		float opacity = smoothstep(0.7, 1.0, base.a);
51
52		float inverse_mie = 0.0;
53
54		if ((opacity == 0.0) && (mie_sign > 0.0)) // Mie forward scattering enhancing light
55				{mie_factor *= (1.0 -  pow(transparency, 2.0));}
56		else if ((opacity == 0.0) && (mie_sign < 0.0))	// Mie forward scattering reducing reflected light
57				{
58				inverse_mie = (1.0 -  pow(transparency, 2.0)) * smoothstep(0.65, 0.8, scattering);
59				inverse_mie *= (1.0 - smoothstep(-1.0, -0.5, mie_frag));
60				}
61		else if (mie_sign > 0.0) // bulk light absorption
62				{mie_factor *= - 4.0 * pow(opacity, 2.0);}
63
64
65	// darken the bulk of the away-facing cloud
66
67	float bulk_shade_factor = (1.0 - 0.6 * geo_factor * smoothstep(0.5, 1.0, mie_frag));
68    bulk_shade_factor -= 0.3 * smoothstep(0.5, 1.0, mie_frag) * (1.0 - mie_frag_mod) * (1.0 - smoothstep(0.4, 0.5, bottom_shade));
69
70
71      float mie_enhancement = 1.0 + clamp(mie_factor, 0.0, 1.0);
72      mie_enhancement = mie_enhancement * bulk_shade_factor;
73
74	 vec4 finalColor = base * gl_Color;
75	 finalColor.rgb *= mie_enhancement * (1.0 - 0.4 * inverse_mie);
76	 finalColor.rgb = max(finalColor.rgb, gl_Color.rgb * 1.2 * bottom_shade);
77
78      finalColor.rgb = mix(hazeColor, finalColor.rgb, fogFactor );
79      finalColor.rgb = filter_combined(finalColor.rgb);
80
81
82      gl_FragColor.rgb = finalColor.rgb;
83      gl_FragColor.a = mix(0.0, finalColor.a, 1.0 - 0.5 * (1.0 - fogFactor));
84}
85