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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 {
float3 color;
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
#if defined(_CUSTOM30_FOG_HEIGHT_DENSITY_MINIMUM)
float height_density_minimum;
#endif
#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
texture2D emitter_texture;
float4 emitter_texture_texelsize;
float3 emitter_world_pos;
float3 emitter_normal;
float3 emitter_tangent;
float3 emitter_normal_x_tangent;
float2 emitter_scale; // [tangent scale in meters, bitangent scale in meters]
float2 emitter_scale_rcp;
#endif
};
#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
// Returns weighted color
float3 getEmitterData(FogParams p, float3 pp)
{
// Using identity a_parallel_to_b = (dot(a, b) / dot(b, b)) * b
// float3 along_tangent = dot(p - em_loc, em_tangent) * em_tangent;
// float3 along_normal_x_tangent = dot(p - em_loc, em_normal_x_tangent) *
// em_normal_x_tangent;
// Given that em_tangent and em_normal_x_tangent are normalized, and the fact
// that we really want uvs, we can simplify this:
float2 uv = float2(dot(pp - p.emitter_world_pos, p.emitter_normal_x_tangent), dot(pp - p.emitter_world_pos, p.emitter_tangent));
uv *= p.emitter_scale_rcp;
uv *= 0.5;
uv += 0.5;
bool in_range = uv.x < 1 && uv.y < 1 && uv.x > 0 && uv.y > 0;
[branch]
if (!in_range) {
return p.color;
}
float4 c = p.emitter_texture.SampleLevel(linear_clamp_s, uv, 0);
return lerp(p.color, c.rgb, c.a);
}
#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;
float4 clipPos = UnityObjectToClipPos(i.objPos);
float2 screen_uv = ComputeScreenPos(clipPos) / clipPos.w;
float zDepthFromMap = SAMPLE_DEPTH_TEXTURE(_CameraDepthTexture, screen_uv);
float linearZ =
GetLinearZFromZDepth_WorksWithMirrors(zDepthFromMap, screen_uv);
// 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 = min(linearZ, 1200);
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;
float4 color = 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);
#if defined(_CUSTOM30_FOG_HEIGHT_DENSITY_MINIMUM)
factor = max(factor, p.height_density_minimum);
#endif
cur_d *= factor;
#endif
cur_d = saturate(cur_d);
#if defined(_RAYMARCHED_FOG_EMITTER_TEXTURE)
float4 cur_c = float4(getEmitterData(p, pp) * cur_d, cur_d);
#else
float4 cur_c = float4(p.color * cur_d, cur_d);
#endif
color += (1.0f - color.a) * cur_c;
}
FogResult r;
r.color = 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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