1 files changed, 209 insertions, 0 deletions
diff --git a/source/blender/draw/engines/eevee_next/shaders/eevee_light_lib.glsl b/source/blender/draw/engines/eevee_next/shaders/eevee_light_lib.glsl
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index 00000000000..58608f6e1f0
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+++ b/source/blender/draw/engines/eevee_next/shaders/eevee_light_lib.glsl
@@ -0,0 +1,209 @@
+
+#pragma BLENDER_REQUIRE(common_math_geom_lib.glsl)
+#pragma BLENDER_REQUIRE(eevee_ltc_lib.glsl)
+#pragma BLENDER_REQUIRE(eevee_light_iter_lib.glsl)
+
+/* ---------------------------------------------------------------------- */
+/** \name Light Functions
+ * \{ */
+
+void light_vector_get(LightData ld, vec3 P, out vec3 L, out float dist)
+{
+  if (ld.type == LIGHT_SUN) {
+    L = ld._back;
+    dist = 1.0;
+  }
+  else {
+    L = ld._position - P;
+    dist = inversesqrt(len_squared(L));
+    L *= dist;
+    dist = 1.0 / dist;
+  }
+}
+
+/* Rotate vector to light's local space. Does not translate. */
+vec3 light_world_to_local(LightData ld, vec3 L)
+{
+  /* Avoid relying on compiler to optimize this.
+   * vec3 lL = transpose(mat3(ld.object_mat)) * L; */
+  vec3 lL;
+  lL.x = dot(ld.object_mat[0].xyz, L);
+  lL.y = dot(ld.object_mat[1].xyz, L);
+  lL.z = dot(ld.object_mat[2].xyz, L);
+  return lL;
+}
+
+/* From Frostbite PBR Course
+ * Distance based attenuation
+ * http://www.frostbite.com/wp-content/uploads/2014/11/course_notes_moving_frostbite_to_pbr.pdf */
+float light_influence_attenuation(float dist, float inv_sqr_influence)
+{
+  float factor = sqr(dist) * inv_sqr_influence;
+  float fac = saturate(1.0 - sqr(factor));
+  return sqr(fac);
+}
+
+float light_spot_attenuation(LightData ld, vec3 L)
+{
+  vec3 lL = light_world_to_local(ld, L);
+  float ellipse = inversesqrt(1.0 + len_squared(lL.xy * ld.spot_size_inv / lL.z));
+  float spotmask = smoothstep(0.0, 1.0, ellipse * ld._spot_mul + ld._spot_bias);
+  return spotmask;
+}
+
+float light_attenuation(LightData ld, vec3 L, float dist)
+{
+  float vis = 1.0;
+  if (ld.type == LIGHT_SPOT) {
+    vis *= light_spot_attenuation(ld, L);
+  }
+  if (ld.type >= LIGHT_SPOT) {
+    vis *= step(0.0, -dot(L, -ld._back));
+  }
+  if (ld.type != LIGHT_SUN) {
+#ifdef VOLUME_LIGHTING
+    vis *= light_influence_attenuation(dist, ld.influence_radius_invsqr_volume);
+#else
+    vis *= light_influence_attenuation(dist, ld.influence_radius_invsqr_surface);
+#endif
+  }
+  return vis;
+}
+
+/* Cheaper alternative than evaluating the LTC.
+ * The result needs to be multiplied by BSDF or Phase Function. */
+float light_point_light(LightData ld, const bool is_directional, vec3 L, float dist)
+{
+  if (is_directional) {
+    return 1.0;
+  }
+  /**
+   * Using "Point Light Attenuation Without Singularity" from Cem Yuksel
+   * http://www.cemyuksel.com/research/pointlightattenuation/pointlightattenuation.pdf
+   * http://www.cemyuksel.com/research/pointlightattenuation/
+   **/
+  float d_sqr = sqr(dist);
+  float r_sqr = ld.radius_squared;
+  /* Using reformulation that has better numerical percision. */
+  float power = 2.0 / (d_sqr + r_sqr + dist * sqrt(d_sqr + r_sqr));
+
+  if (is_area_light(ld.type)) {
+    /* Modulate by light plane orientation / solid angle. */
+    power *= saturate(dot(ld._back, L));
+  }
+  return power;
+}
+
+float light_diffuse(sampler2DArray utility_tx,
+                    const bool is_directional,
+                    LightData ld,
+                    vec3 N,
+                    vec3 V,
+                    vec3 L,
+                    float dist)
+{
+  if (is_directional || !is_area_light(ld.type)) {
+    float radius = ld._radius / dist;
+    return ltc_evaluate_disk_simple(utility_tx, radius, dot(N, L));
+  }
+  else if (ld.type == LIGHT_RECT) {
+    vec3 corners[4];
+    corners[0] = ld._right * ld._area_size_x + ld._up * -ld._area_size_y;
+    corners[1] = ld._right * ld._area_size_x + ld._up * ld._area_size_y;
+    corners[2] = -corners[0];
+    corners[3] = -corners[1];
+
+    corners[0] = normalize(L * dist + corners[0]);
+    corners[1] = normalize(L * dist + corners[1]);
+    corners[2] = normalize(L * dist + corners[2]);
+    corners[3] = normalize(L * dist + corners[3]);
+
+    return ltc_evaluate_quad(utility_tx, corners, N);
+  }
+  else /* (ld.type == LIGHT_ELLIPSE) */ {
+    vec3 points[3];
+    points[0] = ld._right * -ld._area_size_x + ld._up * -ld._area_size_y;
+    points[1] = ld._right * ld._area_size_x + ld._up * -ld._area_size_y;
+    points[2] = -points[0];
+
+    points[0] += L * dist;
+    points[1] += L * dist;
+    points[2] += L * dist;
+
+    return ltc_evaluate_disk(utility_tx, N, V, mat3(1.0), points);
+  }
+}
+
+float light_ltc(sampler2DArray utility_tx,
+                const bool is_directional,
+                LightData ld,
+                vec3 N,
+                vec3 V,
+                vec3 L,
+                float dist,
+                vec4 ltc_mat)
+{
+  if (is_directional || ld.type != LIGHT_RECT) {
+    vec3 Px = ld._right;
+    vec3 Py = ld._up;
+
+    if (is_directional || !is_area_light(ld.type)) {
+      make_orthonormal_basis(L, Px, Py);
+    }
+
+    vec3 points[3];
+    points[0] = Px * -ld._area_size_x + Py * -ld._area_size_y;
+    points[1] = Px * ld._area_size_x + Py * -ld._area_size_y;
+    points[2] = -points[0];
+
+    points[0] += L * dist;
+    points[1] += L * dist;
+    points[2] += L * dist;
+
+    return ltc_evaluate_disk(utility_tx, N, V, ltc_matrix(ltc_mat), points);
+  }
+  else {
+    vec3 corners[4];
+    corners[0] = ld._right * ld._area_size_x + ld._up * -ld._area_size_y;
+    corners[1] = ld._right * ld._area_size_x + ld._up * ld._area_size_y;
+    corners[2] = -corners[0];
+    corners[3] = -corners[1];
+
+    corners[0] += L * dist;
+    corners[1] += L * dist;
+    corners[2] += L * dist;
+    corners[3] += L * dist;
+
+    ltc_transform_quad(N, V, ltc_matrix(ltc_mat), corners);
+
+    return ltc_evaluate_quad(utility_tx, corners, vec3(0.0, 0.0, 1.0));
+  }
+}
+
+vec3 light_translucent(sampler1D transmittance_tx,
+                       const bool is_directional,
+                       LightData ld,
+                       vec3 N,
+                       vec3 L,
+                       float dist,
+                       vec3 sss_radius,
+                       float delta)
+{
+  /* TODO(fclem): We should compute the power at the entry point. */
+  /* NOTE(fclem): we compute the light attenuation using the light vector but the transmittance
+   * using the shadow depth delta. */
+  float power = light_point_light(ld, is_directional, L, dist);
+  /* Do not add more energy on front faces. Also apply lambertian BSDF. */
+  power *= max(0.0, dot(-N, L)) * M_1_PI;
+
+  sss_radius *= SSS_TRANSMIT_LUT_RADIUS;
+  vec3 channels_co = saturate(delta / sss_radius) * SSS_TRANSMIT_LUT_SCALE + SSS_TRANSMIT_LUT_BIAS;
+
+  vec3 translucency;
+  translucency.x = (sss_radius.x > 0.0) ? texture(transmittance_tx, channels_co.x).r : 0.0;
+  translucency.y = (sss_radius.y > 0.0) ? texture(transmittance_tx, channels_co.y).r : 0.0;
+  translucency.z = (sss_radius.z > 0.0) ? texture(transmittance_tx, channels_co.z).r : 0.0;
+  return translucency * power;
+}
+
+/** \} */