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#ifndef __RAY_MARCHING_INC
#define __RAY_MARCHING_INC
#include "math.cginc"
#include "ray_marching_maps.hlsl"
#include "texture_utils.cginc"
#include "vertex.cginc"
struct RayMarchResult {
float3 objPos;
float3 objNorm;
float3 objTan;
};
float3 getObjPos(v2f i)
{
return i.objPos_orig;
}
void GetRoRd(v2f i, out float3 ro, out float3 rd) {
ro = getObjPos(i);
float3 rd_world = normalize(i.worldPos.xyz - _WorldSpaceCameraPos);
rd = mul((float3x3)unity_WorldToObject, rd_world);
}
float map(float3 p) {
float d = 1e9;
#if defined(_RAY_MARCHING_BALL)
{
float r = _Ray_Marching_Ball_Radius;
d = min(d, map_ball(p, _Ray_Marching_Ball_Radius));
}
#endif
#if defined(_RAY_MARCHING_HEXAGON)
{
float r = _Ray_Marching_Hexagon_Radius;
float h = _Ray_Marching_Hexagon_Height;
d = min(d, map_hexagon(p, float2(r, h)));
}
#endif
return d;
}
float domain_repeat(inout float3 p) {
float d;
#if defined(_RAY_MARCHING_CART_GRID)
{
float3 count = float3(_Ray_Marching_Cart_Grid_Count_X, _Ray_Marching_Cart_Grid_Count_Y, _Ray_Marching_Cart_Grid_Count_Z);
float3 period = 1.0f / count;
period *= 2;
float3 half_period = period*0.5f;
float3 which = floor((p + half_period) / period);
if (any(abs(which) > count/2)) {
p = 1e6;
} else {
p = glsl_mod(p + half_period, period) - half_period;
}
d = map(p);
}
#elif defined(_RAY_MARCHING_HEX_GRID)
{
const float3 count = _Ray_Marching_Hex_Grid_Count * 0.5f;
const float3 period = 1.0f / count;
const float3 hex = cart_to_hex(p.xy);
float half_period = period * 0.5;
float3 which = floor((hex + half_period) / period);
// The original code here was this:
// p_hex = glsl_mod(p_hex + half_period, period) - half_period;
//
// But you can simplify it. Given the definition of glsl_mod:
// #define glsl_mod(x,y) (((x)-(y)*floor((x)/(y))))
//
// You can plug in terms:
// (p_hex + half_period) - (period) * floor((p_hex + half_period) / period)
// = p_hex + half_period - period * floor(p_hex/period + 0.5)
//
// For all x,
// round(x) = floor(x + 0.5)
//
// Continuing to simplify:
// (p_hex + half_period - period * round(p_hex/period)) - half_period
// = p_hex - period * round(p_hex / period)
const float3 hex_inst = hex - period * round_hex(hex / period);
p.xy = (any(abs(which) > count/2) ? 1e9 : hex_to_cart(hex_inst));
d = map(p);
}
#endif
return d;
}
void ray_march(inout v2f i) {
#if defined(_RAY_MARCHING)
float3 ro, rd;
GetRoRd(i, ro, rd);
#if defined(_VERTEX_DEFORMATION)
// TODO optimize, we don't need to pass in `dummy`.
float3 dummy = 0;
float3 tmp_pos = ro;
undeform_normal(tmp_pos, dummy, rd);
rd = normalize(rd);
#endif
const float kMinDist = _Ray_Marching_Min_Dist;
const float kMaxDist = _Ray_Marching_Max_Dist;
const uint kMaxIter = _Ray_Marching_Max_Iter;
float d_cur;
float d_acc = 0;
float3 hit_pos;
for (uint ii = 0; ii < kMaxIter; ++ii) {
float3 p = ro + rd * d_acc;
d_cur = domain_repeat(p);
#if defined(_RAY_MARCHING_OVERSTEP)
d_cur *= (d_cur > 0 ? _Ray_Marching_Overstepping_Factor : 1.0f);
#endif
d_acc += d_cur;
if (abs(d_cur) < kMinDist) {
hit_pos = p;
break;
}
if (d_acc > kMaxDist) {
break;
}
}
if (abs(d_cur) > kMinDist) {
discard;
}
float3 lclPos = hit_pos;
float3 lclNorm;
float3 lclTan;
#if defined(_RAY_MARCHING_BALL)
{
float r = _Ray_Marching_Ball_Radius;
map_ball_normal(r, lclPos, lclNorm, lclTan);
}
#endif
#if defined(_RAY_MARCHING_HEXAGON)
{
float r = _Ray_Marching_Hexagon_Radius;
float h = _Ray_Marching_Hexagon_Height;
map_hexagon_normal(float2(r, h), lclPos, lclNorm, lclTan);
}
#endif
i.objPos = lclPos;
i.normal = lclNorm;
i.tangent.xyz = lclTan;
#endif // _RAY_MARCHING
}
#endif // __RAY_MARCHING_INC
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