## displace (`lygia`/`space`/`displace`)

Displace UV space into a XYZ space using an heightmap

Dependencies:

Use:

``````<vec3> displace(<SAMPLER_TYPE> tex, <vec3> ro, <vec3|vec2> rd)
``````

Check it on Github

``````

#ifndef DISPLACE_DEPTH
#define DISPLACE_DEPTH 1.
#endif

#ifndef DISPLACE_PRECISION
#define DISPLACE_PRECISION 0.01
#endif

#ifndef DISPLACE_SAMPLER_FNC
#define DISPLACE_SAMPLER_FNC(TEX, UV) SAMPLER_FNC(TEX, UV).r
#endif

#ifndef DISPLACE_MAX_ITERATIONS
#define DISPLACE_MAX_ITERATIONS 120
#endif

#ifndef FNC_DISPLACE
#define FNC_DISPLACE
vec3 displace(SAMPLER_TYPE tex, vec3 ro, vec3 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
vec3 prev = vec3(
ro.x - rd.x * t,
ro.y - rd.y * t,
ro.z - rd.z * t
);

vec3 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_FNC(tex, 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)) + vec3(0.5, 0.5, 0.0);
}
else
lastD = df;
}

return vec3(0.0, 0.0, 1.0);
}

vec3 displace(SAMPLER_TYPE tex, vec3 ro, vec2 uv) {
vec3 rd = raymarchCamera(ro) * normalize(vec3(uv - 0.5, 1.0));
return displace(tex, ro, rd);
}
#endif
``````

Dependencies:

Use:

``````<float3> displace(<SAMPLER_TYPE> tex, <float3> ro, <float3|float2> rd)
``````

Check it on Github

``````

#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 = raymarchCamera(ro) * normalize(float3(uv - 0.5, 1.0));
return displace(u_tex0Depth, ro, rd);
}
#endif
``````