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-rw-r--r--libdimension/raytrace.c44
1 files changed, 39 insertions, 5 deletions
diff --git a/libdimension/raytrace.c b/libdimension/raytrace.c
index 826cc58..734ff72 100644
--- a/libdimension/raytrace.c
+++ b/libdimension/raytrace.c
@@ -223,6 +223,8 @@ typedef struct dmnsn_raytrace_state {
dmnsn_color pigment;
dmnsn_color diffuse;
dmnsn_color additional;
+
+ double ior;
} dmnsn_raytrace_state;
/* Main helper for dmnsn_raytrace_scene_impl - shoot a ray */
@@ -237,7 +239,8 @@ dmnsn_raytrace_scene_impl(dmnsn_progress *progress, dmnsn_scene *scene,
{
dmnsn_raytrace_state state = {
.scene = scene,
- .bvst = bvst
+ .bvst = bvst,
+ .ior = 1.0
};
unsigned int width = scene->canvas->x;
@@ -434,15 +437,46 @@ static void
dmnsn_raytrace_translucency(dmnsn_raytrace_state *state)
{
if (state->pigment.filter || state->pigment.trans) {
+ dmnsn_line trans_ray = dmnsn_new_line(state->r, state->intersection->ray.n);
+ trans_ray = dmnsn_line_add_epsilon(trans_ray);
+
+ dmnsn_raytrace_state recursive_state = *state;
+
+ double iorr = state->ior; /* ior ratio */
+
+ dmnsn_vector r = dmnsn_vector_normalize(trans_ray.n);
+ dmnsn_vector n = state->intersection->normal;
+
+ if (state->intersection->interior && dmnsn_vector_dot(r, n) < 0.0) {
+ iorr /= state->intersection->interior->ior;
+ recursive_state.ior = state->intersection->interior->ior;
+ }
+
+ double c1 = -dmnsn_vector_dot(r, n);
+ double c2 = 1.0 - iorr*iorr*(1.0 - c1*c1);
+ if (c2 <= 0.0) {
+ /* Total internal reflection */
+ return;
+ }
+ c2 = sqrt(c2);
+
+ if (c1 >= 0.0) {
+ trans_ray.n = dmnsn_vector_add(
+ dmnsn_vector_mul(iorr, r),
+ dmnsn_vector_mul(iorr*c1 - c2, n)
+ );
+ } else {
+ trans_ray.n = dmnsn_vector_add(
+ dmnsn_vector_mul(iorr, r),
+ dmnsn_vector_mul(iorr*c1 + c2, n)
+ );
+ }
+
state->diffuse = dmnsn_color_mul(
1.0 - state->pigment.filter - state->pigment.trans,
state->diffuse
);
- dmnsn_line trans_ray = dmnsn_new_line(state->r, state->intersection->ray.n);
- trans_ray = dmnsn_line_add_epsilon(trans_ray);
-
- dmnsn_raytrace_state recursive_state = *state;
dmnsn_color rec = dmnsn_raytrace_shoot(&recursive_state, trans_ray);
dmnsn_color filtered = dmnsn_color_filter(rec, state->pigment);
state->additional = dmnsn_color_add(filtered, state->additional);