74 lines
No EOL
2 KiB
HLSL
74 lines
No EOL
2 KiB
HLSL
#include "../space/lookAt.hlsl"
|
|
#include "../sampler.hlsl"
|
|
|
|
/*
|
|
contributors: Patricio Gonzalez Vivo
|
|
description: Displace UV space into a XYZ space using an heightmap
|
|
use: <float3> displace(<SAMPLER_TYPE> tex, <float3> ro, <float3|float2> rd)
|
|
license:
|
|
- Copyright (c) 2021 Patricio Gonzalez Vivo under Prosperity License - https://prosperitylicense.com/versions/3.0.0
|
|
- Copyright (c) 2021 Patricio Gonzalez Vivo under Patron License - https://lygia.xyz/license
|
|
*/
|
|
|
|
#ifndef DISPLACE_DEPTH
|
|
#define DISPLACE_DEPTH 1.
|
|
#endif
|
|
|
|
#ifndef DISPLACE_PRECISION
|
|
#define DISPLACE_PRECISION 0.01
|
|
#endif
|
|
|
|
#ifndef DISPLACE_SAMPLER
|
|
#define DISPLACE_SAMPLER(UV) tex2D(tex, UV).r
|
|
#endif
|
|
|
|
#ifndef DISPLACE_MAX_ITERATIONS
|
|
#define DISPLACE_MAX_ITERATIONS 120
|
|
#endif
|
|
|
|
#ifndef FNC_DISPLACE
|
|
#define FNC_DISPLACE
|
|
float3 displace(SAMPLER_TYPE tex, float3 ro, float3 rd) {
|
|
|
|
// the z length of the target vector
|
|
float dz = ro.z - DISPLACE_DEPTH;
|
|
float t = dz / rd.z;
|
|
|
|
// the intersection point between the ray and the hightest point on the plane
|
|
float3 prev = float3(
|
|
ro.x - rd.x * t,
|
|
ro.y - rd.y * t,
|
|
ro.z - rd.z * t
|
|
);
|
|
|
|
float3 curr = prev;
|
|
float lastD = prev.z;
|
|
float hmap = 0.;
|
|
float df = 0.;
|
|
|
|
for (int i = 0; i < DISPLACE_MAX_ITERATIONS; i++) {
|
|
prev = curr;
|
|
curr = prev + rd * DISPLACE_PRECISION;
|
|
|
|
hmap = DISPLACE_SAMPLER( curr.xy - 0.5 );
|
|
// distance to the displaced surface
|
|
float df = curr.z - hmap * DISPLACE_DEPTH;
|
|
|
|
// if we have an intersection
|
|
if (df < 0.0) {
|
|
// linear interpolation to find more precise df
|
|
float t = lastD / (abs(df)+lastD);
|
|
return (prev + t * (curr - prev)) + float3(0.5, 0.5, 0.0);
|
|
}
|
|
else
|
|
lastD = df;
|
|
}
|
|
|
|
return float3(0.0, 0.0, 1.0);
|
|
}
|
|
|
|
float3 displace(SAMPLER_TYPE tex, float3 ro, float2 uv) {
|
|
float3 rd = lookAt(-ro) * normalize(float3(uv - 0.5, 1.0));
|
|
return displace(u_tex0Depth, ro, rd);
|
|
}
|
|
#endif |