etqw-sdk/base/renderprogs/atmosphere.hg
2008-05-29 00:00:00 +00:00

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uniform float4 fog_depths : $fogDepths;
$if ( r_megaDrawMethod == 0 )
uniform float4 fog_parameters : $fogParams;
uniform float3 fog_eyePos : $viewOriginWorld;
$endif
uniform float3 fog_viewOrigin : $viewOrigin;
$if ( r_megaDrawMethod == 0 )
uniform float4 fog_matrix_x : $transposedModelMatrix_x;
uniform float4 fog_matrix_y : $transposedModelMatrix_y;
uniform float4 fog_matrix_z : $transposedModelMatrix_z;
$endif
//MAD result.color.secondary, _F1.x, $fogDepths.z, $fogDepths.w;
float2 Extinction(float3 inpos) {
$if ( r_megaDrawMethod != 0 )
float3 diff = inpos - fog_viewOrigin;
float d = length( diff );
return 1.f-saturate( d * fog_depths.z + fog_depths.w );
$else
float3 eye = fog_eyePos;
float4 iP = float4(inpos,1);
float3 pos;
pos.x = dot( iP, fog_matrix_x );
pos.y = dot( iP, fog_matrix_y );
pos.z = dot( iP, fog_matrix_z );
float oneOverA = fog_parameters.x;
float oneOverB = fog_parameters.y;
float C = fog_parameters.z;
//Cheap clutch for horizontal rays
if (abs(eye.z-pos.z) < 100) {
eye.z = pos.z + 100;
}
float3 ray = (pos - eye);
//Deviation from the vertical ray
float3 rayn = normalize(ray);
float3 up = float3(0,0,1);
float costheta = dot(up, rayn);
float z1 = max(pos.z+C,0);
float z2 = max(eye.z+C,0);
//Integrate along a vertical ray
float dens = pow(0.5,z2*oneOverB)-pow(0.5,z1*oneOverB);
//Correct for horizontal rays
dens = dens/costheta;
//Multiply with distance
float thick = dens*(length(ray)*oneOverA);
float T = pow(0.5, thick);
return float2(T, rayn.z);
$endif
}