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#ifndef __FOG_INC
#define __FOG_INC
#include "audiolink.cginc"
#include "cnlohr.cginc"
#include "interpolators.cginc"
#include "globals.cginc"
#if defined(_RAYMARCHED_FOG)
struct FogParams {
float steps;
float density;
float y_cutoff;
texture2D dithering_noise;
float4 dithering_noise_texelsize;
texture3D density_noise;
float4 density_noise_scale;
float3 velocity;
#if defined(_RAYMARCHED_FOG_DENSITY_EXPONENT)
float density_exponent;
#endif
#if defined(_RAYMARCHED_FOG_HEIGHT_DENSITY)
float height_density_start;
float height_density_half_life;
#endif
};
struct FogResult {
float4 color;
float depth;
};
FogResult raymarched_fog(v2f i, FogParams p)
{
float3 ro = _WorldSpaceCameraPos;
float3 rd = normalize(i.eyeVec.xyz);
const float ro_epsilon = 1E-3;
ro += rd * ro_epsilon;
// TODO maybe we can accelerate this?
float perspective_divide = 1.0f / i.pos.w;
float perspective_factor = length(i.eyeVec.xyz * perspective_divide);
const float2 screen_uv = (i.pos.xy + 0.5) / _ScreenParams.xy;
float zDepthFromMap = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, screen_uv);
float linearZ =
GetLinearZFromZDepth_WorksWithMirrors(zDepthFromMap, screen_uv);
linearZ = min(1E3, linearZ);
// Get intersection with plane at elevation y.
float plane_y = p.y_cutoff;
float distance_to_y = 1E3;
if (abs(rd.y) > 1E-6) {
float t = (plane_y - ro.y) / rd.y;
if (t > 0) {
distance_to_y = min(t, 1E3);
}
}
linearZ = min(linearZ, distance_to_y);
linearZ -= ro_epsilon;
float dither = p.dithering_noise.SampleLevel(point_repeat_s,
screen_uv * _ScreenParams.xy * p.dithering_noise_texelsize.xy, 0).r;
const float frame = ((float) AudioLinkData(ALPASS_GENERALVU + int2(1, 0)).x);
dither = frac(dither + PHI * frame);
ro += rd * dither;
linearZ -= dither;
float step_size = linearZ / p.steps;
float3 pp = ro;
float d = 0;
[loop]
for (uint ii = 0; ii < p.steps; ++ii) {
pp += step_size * rd;
float3 noise_coord = (pp + _Time[0] * p.velocity) * p.density_noise_scale.xyz;
float cur_d = p.density_noise.SampleLevel(bilinear_repeat_s,
noise_coord, 0);
#if defined(_RAYMARCHED_FOG_DENSITY_EXPONENT)
cur_d = pow(cur_d, p.density_exponent);
#endif
cur_d *= p.density * step_size;
#if defined(_RAYMARCHED_FOG_HEIGHT_DENSITY)
float height_clamped = max(pp.y - p.height_density_start, 0);
// if half_life = 2 and start = 0, then
// y=2 -> density = 1/2
// y=4 -> density = 1/4
// y=6 -> density = 1/8
// if half_life = 3 and start = 0, then
// y=3 -> density = 1/2
// y=6 -> density = 1/4
// y=9 -> density = 1/8
float exponent = height_clamped / p.height_density_half_life;
float factor = pow(2, -exponent);
cur_d *= factor;
#endif
cur_d = saturate(cur_d);
d = d + (1 - d) * cur_d;
}
FogResult r;
r.color.rgb = _Raymarched_Fog_Color;
//r.color.rgb = saturate(log(linearZ) / 5.0);
//r.color.rgb = float3(screen_uv, 0);
r.color.a = d;
r.depth = 0.0001; // Very small depth value to render in front
return r;
}
#endif // _RAYMARCHED_FOG
#endif // __FOG_INC
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