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/**
* @file atmosphericsV.glsl
*
* $LicenseInfo:firstyear=2005&license=viewerlgpl$
* $/LicenseInfo$
*/
// varying param funcs
void setSunlitColor(vec3 v);
void setAmblitColor(vec3 v);
void setAdditiveColor(vec3 v);
void setAtmosAttenuation(vec3 v);
void setPositionEye(vec3 v);
vec3 getAdditiveColor();
//varying vec4 vary_CloudUVs;
//varying float vary_CloudDensity;
// Inputs
uniform vec4 morphFactor;
uniform vec3 camPosLocal;
//uniform vec4 camPosWorld;
uniform vec4 lightnorm;
uniform vec4 sunlight_color;
uniform vec4 ambient;
uniform vec4 blue_horizon;
uniform vec4 blue_density;
uniform vec4 haze_horizon;
uniform vec4 haze_density;
uniform vec4 cloud_shadow;
uniform vec4 density_multiplier;
uniform vec4 distance_multiplier;
uniform vec4 max_y;
uniform vec4 glow;
void calcAtmospherics(vec3 inPositionEye) {
vec3 P = inPositionEye;
setPositionEye(P);
//(TERRAIN) limit altitude
if (P.y > max_y.x) P *= (max_y.x / P.y);
if (P.y < -max_y.x) P *= (-max_y.x / P.y);
vec3 tmpLightnorm = lightnorm.xyz;
vec3 Pn = normalize(P);
float Plen = length(P);
vec4 temp1 = vec4(0);
vec3 temp2 = vec3(0);
vec4 blue_weight;
vec4 haze_weight;
vec4 sunlight = sunlight_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 * 1.0 + vec4(haze_density.r) * 0.25) * (density_multiplier.x * max_y.x);
//I had thought blue_density and haze_density should have equal weighting,
//but attenuation due to haze_density tends to seem too strong
temp1 = blue_density + vec4(haze_density.r);
blue_weight = blue_density / temp1;
haze_weight = vec4(haze_density.r) / temp1;
//(TERRAIN) compute sunlight from lightnorm only (for short rays like terrain)
temp2.y = max(0.0, tmpLightnorm.y);
temp2.y = 1. / temp2.y;
sunlight *= exp( - light_atten * temp2.y);
// main atmospheric scattering line integral
temp2.z = Plen * density_multiplier.x;
// Transparency (-> temp1)
// ATI Bugfix -- can't store temp1*temp2.z*distance_multiplier.x in a variable because the ati
// compiler gets confused.
temp1 = exp(-temp1 * temp2.z * distance_multiplier.x);
//final atmosphere attenuation factor
setAtmosAttenuation(temp1.rgb);
//vary_AtmosAttenuation = distance_multiplier / 10000.;
//vary_AtmosAttenuation = density_multiplier * 100.;
//vary_AtmosAttenuation = vec4(Plen / 100000., 0., 0., 1.);
//compute haze glow
//(can use temp2.x as temp because we haven't used it yet)
temp2.x = dot(Pn, tmpLightnorm.xyz);
temp2.x = 1. - temp2.x;
//temp2.x is 0 at the sun and increases away from sun
temp2.x = max(temp2.x, .03); //was glow.y
//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
//add "minimum anti-solar illumination"
temp2.x += .25;
//increase ambient when there are more clouds
vec4 tmpAmbient = ambient + (vec4(1.) - ambient) * cloud_shadow.x * 0.5;
//haze color
setAdditiveColor(
vec3(blue_horizon * blue_weight * (sunlight*(1.-cloud_shadow.x) + tmpAmbient)
+ (haze_horizon.r * haze_weight) * (sunlight*(1.-cloud_shadow.x) * temp2.x
+ tmpAmbient)));
//brightness of surface both sunlight and ambient
setSunlitColor(vec3(sunlight * .5));
setAmblitColor(vec3(tmpAmbient * .25));
setAdditiveColor(getAdditiveColor() * vec3(1.0 - temp1));
// vary_SunlitColor = vec3(0);
// vary_AmblitColor = vec3(0);
// vary_AdditiveColor = vec4(Pn, 1.0);
/*
const float cloudShadowScale = 100.;
// Get cloud uvs for shadowing
vec3 cloudPos = inPositionEye + camPosWorld - cloudShadowScale / 2.;
vary_CloudUVs.xy = cloudPos.xz / cloudShadowScale;
// We can take uv1 and multiply it by (TerrainSpan / CloudSpan)
// cloudUVs *= (((worldMaxZ - worldMinZ) * 20) /40000.);
vary_CloudUVs *= (10000./40000.);
// Offset by sun vector * (CloudAltitude / CloudSpan)
vary_CloudUVs.x += tmpLightnorm.x / tmpLightnorm.y * (3000./40000.);
vary_CloudUVs.y += tmpLightnorm.z / tmpLightnorm.y * (3000./40000.);
*/
}
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