Implement hair in eevee

New implementation of hair for Eevee.

Note: A hard coded "transmission" property is being used. This should
eventually be exposed to the UI, possibly in the form of SSS
properties.

6 files changed, 192 insertions, 9 deletions

diff --git a/source/blender/draw/engines/clay/shaders/clay_particle_vert.glsl b/source/blender/draw/engines/clay/shaders/clay_particle_vert.glsl
index b28b3cadd6f..d4c35d14182 100644
--- a/source/blender/draw/engines/clay/shaders/clay_particle_vert.glsl
+++ b/source/blender/draw/engines/clay/shaders/clay_particle_vert.glsl
@@ -4,7 +4,7 @@ uniform mat3 NormalMatrix;
 uniform mat4 ModelViewMatrix;
 
 in vec3 pos;
-in vec3 tang;
+in vec3 nor;
 in int ind;
 out vec3 tangent;
 out vec3 viewPosition;
@@ -28,7 +28,7 @@ float rand(int s)
 void main()
 {
 	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
-	tangent = normalize(NormalMatrix * tang);
+	tangent = normalize(NormalMatrix * nor);
 	viewPosition = (ModelViewMatrix * vec4(pos, 1.0)).xyz;
 	colRand = rand(ind);
 }
diff --git a/source/blender/draw/engines/eevee/eevee_engine.c b/source/blender/draw/engines/eevee/eevee_engine.c
index 2177d3d065c..915a0065b60 100644
--- a/source/blender/draw/engines/eevee/eevee_engine.c
+++ b/source/blender/draw/engines/eevee/eevee_engine.c
@@ -151,6 +151,7 @@ static void EEVEE_draw_scene(void *vedata)
 	/* Shading pass */
 	DRW_draw_pass(psl->default_pass);
 	DRW_draw_pass(psl->default_flat_pass);
+	DRW_draw_pass(psl->default_hair_pass);
 	DRW_draw_pass(psl->material_pass);
 
 	/* Post Process */
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index c4c331ab1a4..b9ad507c6ce 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -30,6 +30,8 @@
 #include "BLI_dynstr.h"
 #include "BLI_ghash.h"
 
+#include "BKE_particle.h"
+
 #include "GPU_material.h"
 
 #include "eevee_engine.h"
@@ -55,6 +57,7 @@ enum {
 enum {
 	VAR_MAT_MESH     = (1 << 0),
 	VAR_MAT_PROBE    = (1 << 1),
+	VAR_MAT_HAIR     = (1 << 2),
 };
 
 /* *********** STATIC *********** */
@@ -63,6 +66,7 @@ static struct {
 
 	struct GPUShader *default_lit;
 	struct GPUShader *default_lit_flat;
+	struct GPUShader *default_lit_hair;
 
 	struct GPUShader *default_background;
 
@@ -183,12 +187,19 @@ void EEVEE_materials_init(void)
 		        datatoc_lit_surface_vert_glsl, NULL, frag_str,
 		        SHADER_DEFINES
 		        "#define MESH_SHADER\n");
+
 		e_data.default_lit_flat = DRW_shader_create(
 		        datatoc_lit_surface_vert_glsl, NULL, frag_str,
 		        SHADER_DEFINES
 		        "#define MESH_SHADER\n"
 		        "#define USE_FLAT_NORMAL\n");
 
+		e_data.default_lit_hair = DRW_shader_create(
+		        datatoc_lit_surface_vert_glsl, NULL, frag_str,
+		        SHADER_DEFINES
+		        "#define MESH_SHADER\n"
+		        "#define HAIR_SHADER\n");
+
 		MEM_freeN(frag_str);
 
 		/* Textures */
@@ -257,6 +268,15 @@ struct GPUMaterial *EEVEE_material_mesh_get(struct Scene *scene, Material *ma)
 	    SHADER_DEFINES "#define MESH_SHADER\n");
 }
 
+struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma)
+{
+	return GPU_material_from_nodetree(
+	    scene, ma->nodetree, &ma->gpumaterial, &DRW_engine_viewport_eevee_type,
+	    VAR_MAT_HAIR,
+	    datatoc_lit_surface_vert_glsl, NULL, e_data.frag_shader_lib,
+	    SHADER_DEFINES "#define MESH_SHADER\n" "#define HAIR_SHADER\n");
+}
+
 static void add_standard_uniforms(DRWShadingGroup *shgrp, EEVEE_SceneLayerData *sldata)
 {
 	DRW_shgroup_uniform_block(shgrp, "probe_block", sldata->probe_ubo);
@@ -280,6 +300,7 @@ void EEVEE_materials_cache_init(EEVEE_Data *vedata)
 	/* Create Material Ghash */
 	{
 		stl->g_data->material_hash = BLI_ghash_ptr_new("Eevee_material ghash");
+		stl->g_data->hair_material_hash = BLI_ghash_ptr_new("Eevee_hair_material ghash");
 	}
 
 	{
@@ -322,7 +343,7 @@ void EEVEE_materials_cache_init(EEVEE_Data *vedata)
 
 	{
 		struct GPUShader *depth_sh = DRW_shader_create_3D_depth_only();
-		DRWState state = DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS;
+		DRWState state = DRW_STATE_WRITE_DEPTH | DRW_STATE_DEPTH_LESS | DRW_STATE_WIRE;
 		psl->depth_pass = DRW_pass_create("Depth Pass", state);
 		stl->g_data->depth_shgrp = DRW_shgroup_create(depth_sh, psl->depth_pass);
 
@@ -332,7 +353,7 @@ void EEVEE_materials_cache_init(EEVEE_Data *vedata)
 	}
 
 	{
-		DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL;
+		DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_WIRE;
 		psl->default_pass = DRW_pass_create("Default Lit Pass", state);
 		DRWShadingGroup *shgrp = DRW_shgroup_create(e_data.default_lit, psl->default_pass);
 		add_standard_uniforms(shgrp, sldata);
@@ -340,10 +361,14 @@ void EEVEE_materials_cache_init(EEVEE_Data *vedata)
 		psl->default_flat_pass = DRW_pass_create("Default Flat Lit Pass", state);
 		shgrp = DRW_shgroup_create(e_data.default_lit_flat, psl->default_flat_pass);
 		add_standard_uniforms(shgrp, sldata);
+
+		psl->default_hair_pass = DRW_pass_create("Default Hair Lit Pass", state);
+		shgrp = DRW_shgroup_create(e_data.default_lit_hair, psl->default_hair_pass);
+		add_standard_uniforms(shgrp, sldata);
 	}
 
 	{
-		DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL;
+		DRWState state = DRW_STATE_WRITE_COLOR | DRW_STATE_DEPTH_EQUAL | DRW_STATE_WIRE;
 		psl->material_pass = DRW_pass_create("Material Shader Pass", state);
 	}
 }
@@ -441,6 +466,81 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 			}
 		}
 	}
+
+	if (ob->type == OB_MESH) {
+		if (ob != draw_ctx->scene->obedit) {
+			material_hash = stl->g_data->hair_material_hash;
+
+			for (ParticleSystem *psys = ob->particlesystem.first; psys; psys = psys->next) {
+				if (psys_check_enabled(ob, psys, false)) {
+					ParticleSettings *part = psys->part;
+					int draw_as = (part->draw_as == PART_DRAW_REND) ? part->ren_as : part->draw_as;
+
+					if (draw_as == PART_DRAW_PATH && (psys->pathcache || psys->childcache)) {
+						struct Batch *hair_geom = DRW_cache_particles_get_hair(psys);
+						DRWShadingGroup *shgrp = NULL;
+						Material *ma = give_current_material(ob, part->omat);
+						static float mat[4][4];
+
+						unit_m4(mat);
+
+						if (ma == NULL) {
+							ma = &defmaterial;
+						}
+
+						float *color_p = &ma->r;
+						float *metal_p = &ma->ray_mirror;
+						float *spec_p = &ma->spec;
+						float *rough_p = &ma->gloss_mir;
+
+						DRW_shgroup_call_add(stl->g_data->depth_shgrp, hair_geom, mat);
+
+						shgrp = BLI_ghash_lookup(material_hash, (const void *)ma);
+
+						if (shgrp) {
+							DRW_shgroup_call_add(shgrp, hair_geom, mat);
+						}
+						else {
+							if (ma->use_nodes && ma->nodetree) {
+								Scene *scene = draw_ctx->scene;
+								struct GPUMaterial *gpumat = EEVEE_material_hair_get(scene, ma);
+
+								shgrp = DRW_shgroup_material_create(gpumat, psl->material_pass);
+								if (shgrp) {
+									add_standard_uniforms(shgrp, sldata);
+
+									BLI_ghash_insert(material_hash, ma, shgrp);
+
+									DRW_shgroup_call_add(shgrp, hair_geom, mat);
+								}
+								else {
+									/* Shader failed : pink color */
+									static float col[3] = {1.0f, 0.0f, 1.0f};
+									static float half = 0.5f;
+
+									color_p = col;
+									metal_p = spec_p = rough_p = &half;
+								}
+							}
+
+							/* Fallback to default shader */
+							if (shgrp == NULL) {
+								shgrp = DRW_shgroup_create(e_data.default_lit_hair, psl->default_hair_pass);
+								DRW_shgroup_uniform_vec3(shgrp, "basecol", color_p, 1);
+								DRW_shgroup_uniform_float(shgrp, "metallic", metal_p, 1);
+								DRW_shgroup_uniform_float(shgrp, "specular", spec_p, 1);
+								DRW_shgroup_uniform_float(shgrp, "roughness", rough_p, 1);
+
+								BLI_ghash_insert(material_hash, ma, shgrp);
+
+								DRW_shgroup_call_add(shgrp, hair_geom, mat);
+							}
+						}
+					}
+				}
+			}
+		}
+	}
 }
 
 void EEVEE_materials_cache_finish(EEVEE_Data *vedata)
@@ -448,6 +548,7 @@ void EEVEE_materials_cache_finish(EEVEE_Data *vedata)
 	EEVEE_StorageList *stl = ((EEVEE_Data *)vedata)->stl;
 
 	BLI_ghash_free(stl->g_data->material_hash, NULL, NULL);
+	BLI_ghash_free(stl->g_data->hair_material_hash, NULL, NULL);
 }
 
 void EEVEE_materials_free(void)
@@ -455,6 +556,7 @@ void EEVEE_materials_free(void)
 	MEM_SAFE_FREE(e_data.frag_shader_lib);
 	DRW_SHADER_FREE_SAFE(e_data.default_lit);
 	DRW_SHADER_FREE_SAFE(e_data.default_lit_flat);
+	DRW_SHADER_FREE_SAFE(e_data.default_lit_hair);
 	DRW_SHADER_FREE_SAFE(e_data.default_background);
 	DRW_TEXTURE_FREE_SAFE(e_data.util_tex);
-}
\ No newline at end of file
+}
diff --git a/source/blender/draw/engines/eevee/eevee_private.h b/source/blender/draw/engines/eevee/eevee_private.h
index f3b37f41532..f3c8a63a5d7 100644
--- a/source/blender/draw/engines/eevee/eevee_private.h
+++ b/source/blender/draw/engines/eevee/eevee_private.h
@@ -67,6 +67,7 @@ typedef struct EEVEE_PassList {
 	struct DRWPass *depth_pass_cull;
 	struct DRWPass *default_pass;
 	struct DRWPass *default_flat_pass;
+	struct DRWPass *default_hair_pass;
 	struct DRWPass *material_pass;
 	struct DRWPass *background_pass;
 } EEVEE_PassList;
@@ -318,6 +319,7 @@ typedef struct EEVEE_PrivateData {
 	struct DRWShadingGroup *depth_shgrp;
 	struct DRWShadingGroup *depth_shgrp_cull;
 	struct GHash *material_hash;
+	struct GHash *hair_material_hash;
 } EEVEE_PrivateData; /* Transient data */
 
 /* eevee_data.c */
@@ -336,6 +338,7 @@ struct GPUMaterial *EEVEE_material_world_lightprobe_get(struct Scene *scene, str
 struct GPUMaterial *EEVEE_material_world_background_get(struct Scene *scene, struct World *wo);
 struct GPUMaterial *EEVEE_material_mesh_lightprobe_get(struct Scene *scene, Material *ma);
 struct GPUMaterial *EEVEE_material_mesh_get(struct Scene *scene, Material *ma);
+struct GPUMaterial *EEVEE_material_hair_get(struct Scene *scene, Material *ma);
 void EEVEE_materials_free(void);
 
 /* eevee_lights.c */
diff --git a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
index e361f08b26b..8f11835a1cc 100644
--- a/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
+++ b/source/blender/draw/engines/eevee/shaders/lit_surface_frag.glsl
@@ -88,11 +88,74 @@ vec4 texture_octahedron(sampler2DArray tex, vec4 cubevec)
 
 	return texture(tex, vec3(uvs, cubevec.w));
 }
+#ifdef HAIR_SHADER
+vec3 light_diffuse(LightData ld, ShadingData sd, vec3 albedo)
+{
+       if (ld.l_type == SUN) {
+               return direct_diffuse_sun(ld, sd) * albedo;
+       }
+       else if (ld.l_type == AREA) {
+               return direct_diffuse_rectangle(ld, sd) * albedo;
+       }
+       else {
+               return direct_diffuse_sphere(ld, sd) * albedo;
+       }
+}
+
+vec3 light_specular(LightData ld, ShadingData sd, float roughness, vec3 f0)
+{
+       if (ld.l_type == SUN) {
+               return direct_ggx_sun(ld, sd, roughness, f0);
+       }
+       else if (ld.l_type == AREA) {
+               return direct_ggx_rectangle(ld, sd, roughness, f0);
+       }
+       else {
+               return direct_ggx_sphere(ld, sd, roughness, f0);
+       }
+}
 
 void light_shade(
         LightData ld, ShadingData sd, vec3 albedo, float roughness, vec3 f0,
         out vec3 diffuse, out vec3 specular)
 {
+       const float transmission = 0.3; /* Uniform internal scattering factor */
+       ShadingData sd_new = sd;
+
+       vec3 lamp_vec;
+
+      if (ld.l_type == SUN || ld.l_type == AREA) {
+               lamp_vec = ld.l_forward;
+       }
+       else {
+               lamp_vec = -sd.l_vector;
+       }
+
+       vec3 norm_view = cross(sd.V, sd.N);
+       norm_view = normalize(cross(norm_view, sd.N)); /* Normal facing view */
+
+       vec3 norm_lamp = cross(lamp_vec, sd.N);
+       norm_lamp = normalize(cross(sd.N, norm_lamp)); /* Normal facing lamp */
+
+       /* Rotate view vector onto the cross(tangent, light) plane */
+       vec3 view_vec = normalize(norm_lamp * dot(norm_view, sd.V) + sd.N * dot(sd.N, sd.V));
+
+       float occlusion = (dot(norm_view, norm_lamp) * 0.5 + 0.5);
+       float occltrans = transmission + (occlusion * (1.0 - transmission)); /* Includes transmission component */
+
+       sd_new.N = -norm_lamp;
+
+       diffuse = light_diffuse(ld, sd_new, albedo) * occltrans;
+
+       sd_new.V = view_vec;
+
+       specular = light_specular(ld, sd_new, roughness, f0) * occlusion;
+}
+#else
+void light_shade(
+        LightData ld, ShadingData sd, vec3 albedo, float roughness, vec3 f0,
+        out vec3 diffuse, out vec3 specular)
+{
 #ifdef USE_LTC
 	if (ld.l_type == SUN) {
 		/* TODO disk area light */
@@ -118,6 +181,7 @@ void light_shade(
 	}
 #endif
 }
+#endif
 
 void light_visibility(LightData ld, ShadingData sd, out float vis)
 {
@@ -254,20 +318,33 @@ vec3 eevee_surface_lit(vec3 world_normal, vec3 albedo, vec3 f0, float roughness,
 	sd.W = worldPosition;
 
 	vec3 radiance = vec3(0.0);
+
+#ifdef HAIR_SHADER
+       /* View facing normal */
+       vec3 norm_view = cross(sd.V, sd.N);
+       norm_view = normalize(cross(norm_view, sd.N)); /* Normal facing view */
+#endif
+
+
 	/* Analitic Lights */
 	for (int i = 0; i < MAX_LIGHT && i < light_count; ++i) {
 		LightData ld = lights_data[i];
 		vec3 diff, spec;
-		float vis;
+		float vis = 1.0;
 
 		sd.l_vector = ld.l_position - worldPosition;
 
+#ifndef HAIR_SHADER
 		light_visibility(ld, sd, vis);
+#endif
 		light_shade(ld, sd, albedo, roughnessSquared, f0, diff, spec);
 
 		radiance += vis * (diff + spec) * ld.l_color;
 	}
 
+#ifdef HAIR_SHADER
+	sd.N = -norm_view;
+#endif
 
 	/* Envmaps */
 	vec3 R = reflect(-sd.V, sd.N);
@@ -314,4 +391,4 @@ vec3 eevee_surface_lit(vec3 world_normal, vec3 albedo, vec3 f0, float roughness,
 	        diff_accum.rgb * albedo;
 
 	return radiance + indirect_radiance * ao;
-}
\ No newline at end of file
+}
diff --git a/source/blender/draw/intern/draw_cache_impl_particles.c b/source/blender/draw/intern/draw_cache_impl_particles.c
index f4b16f1873a..febba333a2b 100644
--- a/source/blender/draw/intern/draw_cache_impl_particles.c
+++ b/source/blender/draw/intern/draw_cache_impl_particles.c
@@ -183,7 +183,7 @@ static void particle_batch_cache_ensure_pos_and_seg(ParticleSystem *psys, Partic
 		if (format.attrib_ct == 0) {
 			/* initialize vertex format */
 			attr_id.pos = VertexFormat_add_attrib(&format, "pos", COMP_F32, 3, KEEP_FLOAT);
-			attr_id.tan = VertexFormat_add_attrib(&format, "tang", COMP_F32, 3, KEEP_FLOAT);
+			attr_id.tan = VertexFormat_add_attrib(&format, "nor", COMP_F32, 3, KEEP_FLOAT);
 			attr_id.ind = VertexFormat_add_attrib(&format, "ind", COMP_I32, 1, KEEP_INT);
 		}