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#version 120
#define saturate(x) clamp(x,0.0,1.0)
#define lerp mix
#define COUNT 40
#define FIRST_PASS
#line 52
uniform sampler2D Base;
uniform sampler2D Bump;
uniform sampler3D Fog;
uniform sampler3D LightMap;
varying vec2 texCoord;
varying vec3 lVec;
varying vec3 vVec;
varying vec3 dir;
varying vec3 fogCrd;
varying vec3 shadowCrd;
uniform float fogStart;
uniform vec3 shadowStart;
uniform vec4 fogScaleBias;
uniform vec3 shadowScale, shadowBias;
void main(){
const vec3 fogColor = vec3(0.9, 1.0, 0.8);
const float fogDensity = 0.005;
float n = fogDensity * length(dir);
vec3 fogCoord = fogCrd;
vec3 shadowCoord = shadowCrd;
#ifdef FIRST_PASS
// Regular per pixel lighting
float atten = 1.0 / (1.0 + 0.000001 * dot(lVec, lVec));
vec3 lightVec = normalize(lVec);
vec3 viewVec = normalize(vVec);
vec3 base = texture2D(Base, texCoord).rgb;
vec3 normal = normalize(texture2D(Bump, texCoord).xyz * 2.0 - 1.0);
float diffuse = saturate(dot(lightVec, normal));
float specular = pow(saturate(dot(reflect(-viewVec, normal), lightVec)), 16.0);
float shadow = texture3D(LightMap, shadowCrd).x;
vec3 lighting = atten * shadow * (diffuse * base + 0.5 * specular) + 0.14 * base;
#else
// For later passes, continue the fog computation where we stopped last pass
fogCoord += fogStart * dir;
shadowCoord += shadowStart * dir;
#endif
float a = 1.0;
float b = 0.0;
// Volumetric fog computation
for (int i = 0; i < COUNT; i++){
fogCoord += fogScaleBias.w * dir;
shadowCoord += shadowScale * dir;
float fog = texture3D(Fog, fogCoord).x;
float shadow = texture3D(LightMap, shadowCoord).x;
// Compute weighting factors. This implements the commented out lerp more efficiently.
float x = 1.0 - fog * n;
a *= x;
b = lerp(shadow, b, x);
}
#ifdef FIRST_PASS
gl_FragColor.rgb = lighting * a + fogColor * b;
#else
// "lighting" is in the framebuffer, so we use alpha blending to multiply it with "a".
gl_FragColor.rgb = b * fogColor;
gl_FragColor.a = a;
#endif
}
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