Eevee: Shadows: Add Contact Shadows

This add the possibility to add screen space raytraced shadows to fix light leaking cause by shadows maps.

Theses inherit of the same artifacts as other screenspace methods.

1 files changed, 31 insertions, 1 deletions

diff --git a/source/blender/draw/engines/eevee/shaders/lamps_lib.glsl b/source/blender/draw/engines/eevee/shaders/lamps_lib.glsl
index 676aa2c9748..a39f04d47af 100644
--- a/source/blender/draw/engines/eevee/shaders/lamps_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lamps_lib.glsl
@@ -144,7 +144,7 @@ float shadow_cascade(ShadowData sd, ShadowCascadeData scd, float texid, vec3 W)
 /* ----------------------------------------------------------- */
 #define MAX_MULTI_SHADOW 4
 
-float light_visibility(LightData ld, vec3 W, vec4 l_vector)
+float light_visibility(LightData ld, vec3 W, vec3 viewPosition, vec3 viewNormal, vec4 l_vector)
 {
 	float vis = 1.0;
 
@@ -169,6 +169,7 @@ float light_visibility(LightData ld, vec3 W, vec4 l_vector)
 	/* shadowing */
 	if (ld.l_shadowid >= 0.0) {
 		ShadowData data = shadows_data[int(ld.l_shadowid)];
+
 		if (ld.l_type == SUN) {
 			/* TODO : MSM */
 			// for (int i = 0; i < MAX_MULTI_SHADOW; ++i) {
@@ -185,6 +186,35 @@ float light_visibility(LightData ld, vec3 W, vec4 l_vector)
 					data.sh_tex_start, W);
 			// }
 		}
+#endif
+
+#ifndef VOLUMETRICS
+		/* Only compute if not already in shadow. */
+		if ((vis > 0.001) && (data.sh_contact_dist > 0.0)) {
+			vec4 L = (ld.l_type != SUN) ? l_vector : vec4(-ld.l_forward, 1.0);
+			float trace_distance = (ld.l_type != SUN) ? min(data.sh_contact_dist, l_vector.w) : data.sh_contact_dist;
+
+			vec3 T, B;
+			make_orthonormal_basis(L.xyz / L.w, T, B);
+
+			vec3 rand = texture(utilTex, vec3(gl_FragCoord.xy / LUT_SIZE, 2.0)).xzw;
+			rand.yz *= rand.x * data.sh_contact_spread;
+
+			/* We use the full l_vector.xyz so that the spread is minimize
+			 * if the shading point is further away from the light source */
+			vec3 ray_dir = L.xyz + T * rand.y + B * rand.z;
+			ray_dir = transform_direction(ViewMatrix, ray_dir);
+			ray_dir = normalize(ray_dir);
+			vec3 ray_origin = viewPosition + viewNormal * data.sh_contact_offset;
+			vec3 hit_pos = raycast(-1, ray_origin, ray_dir * trace_distance, data.sh_contact_thickness, rand.x, 0.75, 0.01);
+
+			if (hit_pos.z > 0.0) {
+				hit_pos = get_view_space_from_depth(hit_pos.xy, hit_pos.z);
+				float hit_dist = distance(viewPosition, hit_pos);
+				float dist_ratio = hit_dist / trace_distance;
+				return mix(0.0, vis, dist_ratio * dist_ratio * dist_ratio);
+			}
+		}
 	}
 #endif