Use a 2D texture for the hair interpolation data instead of 1D for larger number of hairs.

It turns out that 1D textures have the same size limit on their 1 axis as 2D textures.
This limits the potential number of hair dramatically, even though the actual size of
the texture is very small. Using a 2D texture and wrapping the index avoids this problem.

10 files changed, 193 insertions, 119 deletions

diff --git a/source/blender/blenkernel/BKE_editstrands.h b/source/blender/blenkernel/BKE_editstrands.h
index 9199668fb9e..e5858160f65 100644
--- a/source/blender/blenkernel/BKE_editstrands.h
+++ b/source/blender/blenkernel/BKE_editstrands.h
@@ -85,10 +85,11 @@ bool BKE_editstrands_hair_ensure(struct BMEditStrands *es);
 void BKE_editstrands_hair_free(struct BMEditStrands *es);
 
 int* BKE_editstrands_hair_get_fiber_lengths(struct BMEditStrands *es);
-void BKE_editstrands_hair_get_texture_buffer(struct BMEditStrands *es, void **texbuffer, int *r_size,
-                                             int *strand_map_start,
-                                             int *strand_vertex_start,
-                                             int *fiber_start);
+void BKE_editstrands_hair_get_texture_buffer_size(struct BMEditStrands *es, int *r_size,
+                                                  int *r_strand_map_start,
+                                                  int *r_strand_vertex_start,
+                                                  int *r_fiber_start);
+void BKE_editstrands_hair_get_texture_buffer(struct BMEditStrands *es, void *texbuffer);
 
 /* === Constraints === */
 
diff --git a/source/blender/blenkernel/BKE_hair.h b/source/blender/blenkernel/BKE_hair.h
index 4169a3b6f16..5eafc14e66f 100644
--- a/source/blender/blenkernel/BKE_hair.h
+++ b/source/blender/blenkernel/BKE_hair.h
@@ -68,9 +68,11 @@ struct HairFiber* BKE_hair_fibers_create(const struct StrandsView *strands,
 int* BKE_hair_get_fiber_lengths(const struct HairFiber *fibers, int totfibers,
                                  const struct StrandsView *strands);
 
+void BKE_hair_get_texture_buffer_size(const struct StrandsView *strands, int totfibers,
+                                      int *r_size, int *r_strand_map_start,
+                                      int *r_strand_vertex_start, int *r_fiber_start);
 void BKE_hair_get_texture_buffer(const struct StrandsView *strands, struct DerivedMesh *scalp,
                                  const struct HairFiber *fibers, int totfibers,
-                                 void **r_texbuffer, int *r_size, int *r_strand_map_start,
-                                 int *r_strand_vertex_start, int *r_fiber_start);
+                                 void *texbuffer);
 
 #endif
diff --git a/source/blender/blenkernel/intern/editstrands.c b/source/blender/blenkernel/intern/editstrands.c
index 16e47aabf91..0fe286a5d3a 100644
--- a/source/blender/blenkernel/intern/editstrands.c
+++ b/source/blender/blenkernel/intern/editstrands.c
@@ -239,14 +239,20 @@ int* BKE_editstrands_hair_get_fiber_lengths(BMEditStrands *es)
 	return BKE_hair_get_fiber_lengths(es->hair_fibers, es->hair_totfibers, &strands.base);
 }
 
-void BKE_editstrands_hair_get_texture_buffer(BMEditStrands *es, void **r_texbuffer, int *r_size,
-                                             int *r_strand_map_start,
-                                             int *r_strand_vertex_start,
-                                             int *r_fiber_start)
+void BKE_editstrands_hair_get_texture_buffer_size(BMEditStrands *es, int *r_size,
+                                                  int *r_strand_map_start,
+                                                  int *r_strand_vertex_start,
+                                                  int *r_fiber_start)
 {
 	EditStrandsView strands = editstrands_get_view(es);
-	BKE_hair_get_texture_buffer(&strands.base, es->root_dm, es->hair_fibers, es->hair_totfibers,
-	                            r_texbuffer, r_size, r_strand_map_start, r_strand_vertex_start, r_fiber_start);
+	BKE_hair_get_texture_buffer_size(&strands.base, es->hair_totfibers,
+	                                 r_size, r_strand_map_start, r_strand_vertex_start, r_fiber_start);
+}
+
+void BKE_editstrands_hair_get_texture_buffer(BMEditStrands *es, void *texbuffer)
+{
+	EditStrandsView strands = editstrands_get_view(es);
+	BKE_hair_get_texture_buffer(&strands.base, es->root_dm, es->hair_fibers, es->hair_totfibers, texbuffer);
 }
 
 /* === Constraints === */
diff --git a/source/blender/blenkernel/intern/hair.c b/source/blender/blenkernel/intern/hair.c
index 838956ea843..59677a25bc1 100644
--- a/source/blender/blenkernel/intern/hair.c
+++ b/source/blender/blenkernel/intern/hair.c
@@ -374,60 +374,60 @@ static void hair_get_fiber_buffer(const HairFiber *fibers, int totfibers, Derive
 	}
 }
 
+void BKE_hair_get_texture_buffer_size(const StrandsView *strands, int totfibers,
+                                      int *r_size, int *r_strand_map_start,
+                                      int *r_strand_vertex_start, int *r_fiber_start)
+{
+	const int totstrands = strands->get_num_strands(strands);
+	const int totverts = strands->get_num_verts(strands);
+	*r_strand_map_start = 0;
+	*r_strand_vertex_start = *r_strand_map_start + totstrands * sizeof(HairStrandMapTextureBuffer);
+	*r_fiber_start = *r_strand_vertex_start + totverts * sizeof(HairStrandVertexTextureBuffer);
+	*r_size = *r_fiber_start + totfibers * sizeof(HairFiberTextureBuffer);
+}
+
 void BKE_hair_get_texture_buffer(const StrandsView *strands, DerivedMesh *scalp,
                                  const HairFiber *fibers, int totfibers,
-                                 void **r_texbuffer, int *r_size, int *r_strand_map_start,
-                                 int *r_strand_vertex_start, int *r_fiber_start)
+                                 void *buffer)
 {
 	const int totstrands = strands->get_num_strands(strands);
 	const int totverts = strands->get_num_verts(strands);
 	const int strand_map_start = 0;
 	const int strand_vertex_start = strand_map_start + totstrands * sizeof(HairStrandMapTextureBuffer);
 	const int fiber_start = strand_vertex_start + totverts * sizeof(HairStrandVertexTextureBuffer);
-	const int size = fiber_start + totfibers * sizeof(HairFiberTextureBuffer);
 	
-	void *buffer = MEM_mallocN(size, "hair texture buffer");
+	int *lengths = MEM_mallocN(sizeof(int) * totstrands, "strand lengths");
+	MeshSample *roots = MEM_mallocN(sizeof(MeshSample) * totstrands, "strand roots");
+	float (*positions)[3] = MEM_mallocN(sizeof(float[3]) * totverts, "strand vertex positions");
 	
-	{
-		int *lengths = MEM_mallocN(sizeof(int) * totstrands, "strand lengths");
-		MeshSample *roots = MEM_mallocN(sizeof(MeshSample) * totstrands, "strand roots");
-		float (*positions)[3] = MEM_mallocN(sizeof(float[3]) * totverts, "strand vertex positions");
-		
-		strands->get_strand_lengths(strands, lengths);
-		strands->get_strand_roots(strands, roots);
-		strands->get_strand_vertices(strands, positions);
+	strands->get_strand_lengths(strands, lengths);
+	strands->get_strand_roots(strands, roots);
+	strands->get_strand_vertices(strands, positions);
+	
+	HairStrandMapTextureBuffer *smap = (HairStrandMapTextureBuffer*)((char*)buffer + strand_map_start);
+	HairStrandVertexTextureBuffer *svert = (HairStrandVertexTextureBuffer*)((char*)buffer + strand_vertex_start);
+	unsigned int vertex_start = 0;
+	for (int i = 0; i < totstrands; ++i) {
+		const unsigned int len = lengths[i];
+		smap->vertex_start = vertex_start;
+		smap->vertex_count = len;
 		
-		HairStrandMapTextureBuffer *smap = (HairStrandMapTextureBuffer*)((char*)buffer + strand_map_start);
-		HairStrandVertexTextureBuffer *svert = (HairStrandVertexTextureBuffer*)((char*)buffer + strand_vertex_start);
-		unsigned int vertex_start = 0;
-		for (int i = 0; i < totstrands; ++i) {
-			const unsigned int len = lengths[i];
-			smap->vertex_start = vertex_start;
-			smap->vertex_count = len;
-			
-			{
-				float pos[3];
-				float matrix[3][3];
-				BKE_mesh_sample_eval(scalp, &roots[i], pos, matrix[2], matrix[0]);
-				cross_v3_v3v3(matrix[1], matrix[2], matrix[0]);
-				hair_strand_calc_verts(positions + vertex_start, len, matrix, svert);
-			}
-			
-			vertex_start += len;
-			++smap;
-			svert += len;
+		{
+			float pos[3];
+			float matrix[3][3];
+			BKE_mesh_sample_eval(scalp, &roots[i], pos, matrix[2], matrix[0]);
+			cross_v3_v3v3(matrix[1], matrix[2], matrix[0]);
+			hair_strand_calc_verts(positions + vertex_start, len, matrix, svert);
 		}
 		
-		MEM_freeN(lengths);
-		MEM_freeN(roots);
-		MEM_freeN(positions);
+		vertex_start += len;
+		++smap;
+		svert += len;
 	}
 	
-	hair_get_fiber_buffer(fibers, totfibers, scalp, (HairFiberTextureBuffer*)((char*)buffer + fiber_start));
+	MEM_freeN(lengths);
+	MEM_freeN(roots);
+	MEM_freeN(positions);
 	
-	*r_strand_map_start = strand_map_start;
-	*r_strand_vertex_start = strand_vertex_start;
-	*r_fiber_start = fiber_start;
-	*r_texbuffer = buffer;
-	*r_size = size;
+	hair_get_fiber_buffer(fibers, totfibers, scalp, (HairFiberTextureBuffer*)((char*)buffer + fiber_start));
 }
diff --git a/source/blender/draw/CMakeLists.txt b/source/blender/draw/CMakeLists.txt
index b4527361615..1fada0e6f93 100644
--- a/source/blender/draw/CMakeLists.txt
+++ b/source/blender/draw/CMakeLists.txt
@@ -62,6 +62,7 @@ set(SRC
 	intern/draw_cache_impl_particles.c
 	intern/draw_cache_impl_strands.c
 	intern/draw_common.c
+	intern/draw_hair.c
 	intern/draw_manager.c
 	intern/draw_manager_text.c
 	intern/draw_view.c
diff --git a/source/blender/draw/engines/eevee/eevee_materials.c b/source/blender/draw/engines/eevee/eevee_materials.c
index 1c937cac92e..a50b5b62e62 100644
--- a/source/blender/draw/engines/eevee/eevee_materials.c
+++ b/source/blender/draw/engines/eevee/eevee_materials.c
@@ -196,7 +196,7 @@ static char *eevee_get_defines(int options)
 		BLI_dynstr_appendf(ds, "#define HAIR_SHADER\n");
 	}
 	if ((options & VAR_MAT_HAIR_FIBERS) != 0) {
-		BLI_dynstr_appendf(ds, "#define HAIR_SHADER_FIBERS\n");
+		BLI_dynstr_append(ds, DRW_hair_shader_defines());
 	}
 	if ((options & VAR_MAT_PROBE) != 0) {
 		BLI_dynstr_appendf(ds, "#define PROBE_CAPTURE\n");
@@ -381,12 +381,15 @@ void EEVEE_materials_init(EEVEE_StorageList *stl)
 		        "#define CLIP_PLANES\n");
 
 		e_data.default_prepass_hair_fiber_sh = DRW_shader_create(
-		        hair_fiber_vert_str, NULL, datatoc_prepass_frag_glsl,
-		        "#define HAIR_SHADER\n#define HAIR_SHADER_FIBERS\n");
+		        hair_fiber_vert_str, NULL, datatoc_prepass_frag_glsl, DRW_hair_shader_defines());
 
-		e_data.default_prepass_hair_fiber_clip_sh = DRW_shader_create(
-		        hair_fiber_vert_str, NULL, datatoc_prepass_frag_glsl,
-		        "#define HAIR_SHADER\n#define HAIR_SHADER_FIBERS\n#define CLIP_PLANES\n");
+		{
+			char defines[256];
+			BLI_snprintf(defines, sizeof(defines), "#define CLIP_PLANES\n%s",
+			             DRW_hair_shader_defines());
+			e_data.default_prepass_hair_fiber_clip_sh = DRW_shader_create(
+			        hair_fiber_vert_str, NULL, datatoc_prepass_frag_glsl, defines);
+		}
 
 		MEM_freeN(frag_str);
 		MEM_freeN(hair_fiber_vert_str);
@@ -1122,11 +1125,8 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 						bool use_fibers = false;
 						float mat[4][4];
 						struct Gwn_Batch *hair_geom = NULL;
+						const DRWHairFiberTextureBuffer *fiber_buffer = NULL;
 						GPUTexture **fiber_texture = NULL;
-						const float *ribbon_width = NULL;
-						const int *strand_map_start = NULL;
-						const int *strand_vertex_start = NULL;
-						const int *fiber_start = NULL;
 
 						if (ob->mode & OB_MODE_HAIR_EDIT) {
 							BMEditStrands *edit = psys->hairedit;
@@ -1136,16 +1136,12 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 								use_fibers = true;
 								copy_m4_m4(mat, ob->obmat);
 								
-								const DRWHairFiberTextureBuffer *buffer = NULL;
-								hair_geom = DRW_cache_editstrands_get_hair_fibers(edit, true, &buffer);
+								hair_geom = DRW_cache_editstrands_get_hair_fibers(edit, true, &fiber_buffer);
+								
 								if (!edit->texture) {
-									edit->texture = DRW_texture_create_1D(buffer->size, DRW_TEX_RG_32, 0, buffer->data);
+									edit->texture = DRW_texture_create_2D(fiber_buffer->width, fiber_buffer->height,
+									                                      DRW_TEX_RG_32, 0, fiber_buffer->data);
 								}
-								
-								ribbon_width = &tsettings->hair_draw_size;
-								strand_map_start = &buffer->strand_map_start;
-								strand_vertex_start = &buffer->strand_vertex_start;
-								fiber_start = &buffer->fiber_start;
 								fiber_texture = (GPUTexture **)(&edit->texture);
 							}
 						}
@@ -1169,24 +1165,13 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 								DRW_shgroup_call_add(stl->g_data->depth_shgrp_clip, hair_geom, mat);
 							}
 							else {
-								DRWShadingGroup *depth_shgrp = stl->g_data->depth_shgrp_hair_fibers;
-								DRWShadingGroup *depth_clip_shgrp = stl->g_data->depth_shgrp_hair_fibers_clip;
-								DRW_shgroup_call_add(depth_shgrp, hair_geom, mat);
-								DRW_shgroup_call_add(depth_clip_shgrp, hair_geom, mat);
-								
-								DRW_shgroup_uniform_vec2(depth_shgrp, "viewport_size", DRW_viewport_size_get(), 1);
-								DRW_shgroup_uniform_vec2(depth_clip_shgrp, "viewport_size", DRW_viewport_size_get(), 1);
-								DRW_shgroup_uniform_float(depth_shgrp, "ribbon_width", ribbon_width, 1);
-								DRW_shgroup_uniform_float(depth_clip_shgrp, "ribbon_width", ribbon_width, 1);
+								DRW_shgroup_call_add(stl->g_data->depth_shgrp_hair_fibers, hair_geom, mat);
+								DRW_hair_shader_uniforms(stl->g_data->depth_shgrp_hair_fibers, scene,
+								                         fiber_texture, fiber_buffer);
 								
-								DRW_shgroup_uniform_buffer(depth_shgrp, "strand_data", fiber_texture);
-								DRW_shgroup_uniform_buffer(depth_clip_shgrp, "strand_data", fiber_texture);
-								DRW_shgroup_uniform_int(depth_shgrp, "strand_map_start", strand_map_start, 1);
-								DRW_shgroup_uniform_int(depth_clip_shgrp, "strand_map_start", strand_map_start, 1);
-								DRW_shgroup_uniform_int(depth_shgrp, "strand_vertex_start", strand_vertex_start, 1);
-								DRW_shgroup_uniform_int(depth_clip_shgrp, "strand_vertex_start", strand_vertex_start, 1);
-								DRW_shgroup_uniform_int(depth_shgrp, "fiber_start", fiber_start, 1);
-								DRW_shgroup_uniform_int(depth_clip_shgrp, "fiber_start", fiber_start, 1);
+								DRW_shgroup_call_add(stl->g_data->depth_shgrp_hair_fibers_clip, hair_geom, mat);
+								DRW_hair_shader_uniforms(stl->g_data->depth_shgrp_hair_fibers_clip, scene,
+								                         fiber_texture, fiber_buffer);
 							}
 							
 							DRWShadingGroup *shgrp = BLI_ghash_lookup(material_hash, (const void *)ma);
@@ -1233,13 +1218,8 @@ void EEVEE_materials_cache_populate(EEVEE_Data *vedata, EEVEE_SceneLayerData *sl
 								DRW_shgroup_call_add(shgrp, hair_geom, mat);
 								
 								if (use_fibers) {
-									DRW_shgroup_uniform_vec2(shgrp, "viewport_size", DRW_viewport_size_get(), 1);
-									DRW_shgroup_uniform_float(shgrp, "ribbon_width", ribbon_width, 1);
-									
-									DRW_shgroup_uniform_buffer(shgrp, "strand_data", fiber_texture);
-									DRW_shgroup_uniform_int(shgrp, "strand_map_start", strand_map_start, 1);
-									DRW_shgroup_uniform_int(shgrp, "strand_vertex_start", strand_vertex_start, 1);
-									DRW_shgroup_uniform_int(shgrp, "fiber_start", fiber_start, 1);
+									DRW_hair_shader_uniforms(shgrp, scene,
+									                         fiber_texture, fiber_buffer);
 								}
 							}
 						}
diff --git a/source/blender/draw/engines/eevee/shaders/hair_lib.glsl b/source/blender/draw/engines/eevee/shaders/hair_lib.glsl
index 430fee1bc2c..4cbf69e1074 100644
--- a/source/blender/draw/engines/eevee/shaders/hair_lib.glsl
+++ b/source/blender/draw/engines/eevee/shaders/hair_lib.glsl
@@ -1,8 +1,8 @@
-#ifdef HAIR_SHADER
+#ifdef HAIR_SHADER_FIBERS
 
 #define FIBER_RIBBON
 
-uniform sampler1D strand_data;
+uniform sampler2D strand_data;
 uniform int strand_map_start;
 uniform int strand_vertex_start;
 uniform int fiber_start;
@@ -13,6 +13,12 @@ uniform vec2 viewport_size;
 
 #define INDEX_INVALID -1
 
+vec2 read_texdata(int offset)
+{
+	ivec2 offset2 = ivec2(offset % HAIR_SHADER_TEX_WIDTH, offset / HAIR_SHADER_TEX_WIDTH);
+	return texelFetch(strand_data, offset2, 0).rg;
+}
+
 mat3 mat3_from_vectors(vec3 nor, vec3 tang)
 {
 	tang = normalize(tang);
@@ -23,7 +29,7 @@ mat3 mat3_from_vectors(vec3 nor, vec3 tang)
 void get_strand_data(int index, out int start, out int count)
 {
 	int offset = strand_map_start + index;
-	vec4 a = texelFetch(strand_data, offset, 0);
+	vec2 a = read_texdata(offset);
 
 	start = floatBitsToInt(a.r);
 	count = floatBitsToInt(a.g);
@@ -32,11 +38,11 @@ void get_strand_data(int index, out int start, out int count)
 void get_strand_vertex(int index, out vec3 co, out vec3 nor, out vec3 tang)
 {
 	int offset = strand_vertex_start + index * 5;
-	vec4 a = texelFetch(strand_data, offset, 0);
-	vec4 b = texelFetch(strand_data, offset + 1, 0);
-	vec4 c = texelFetch(strand_data, offset + 2, 0);
-	vec4 d = texelFetch(strand_data, offset + 3, 0);
-	vec4 e = texelFetch(strand_data, offset + 4, 0);
+	vec2 a = read_texdata(offset);
+	vec2 b = read_texdata(offset + 1);
+	vec2 c = read_texdata(offset + 2);
+	vec2 d = read_texdata(offset + 3);
+	vec2 e = read_texdata(offset + 4);
 
 	co = vec3(a.rg, b.r);
 	nor = vec3(b.g, c.rg);
@@ -46,8 +52,8 @@ void get_strand_vertex(int index, out vec3 co, out vec3 nor, out vec3 tang)
 void get_strand_root(int index, out vec3 co)
 {
 	int offset = strand_vertex_start + index * 5;
-	vec4 a = texelFetch(strand_data, offset, 0);
-	vec4 b = texelFetch(strand_data, offset + 1, 0);
+	vec2 a = read_texdata(offset);
+	vec2 b = read_texdata(offset + 1);
 
 	co = vec3(a.rg, b.r);
 }
@@ -55,12 +61,12 @@ void get_strand_root(int index, out vec3 co)
 void get_fiber_data(int fiber_index, out ivec4 parent_index, out vec4 parent_weight, out vec3 pos)
 {
 	int offset = fiber_start + fiber_index * 6;
-	vec4 a = texelFetch(strand_data, offset, 0);
-	vec4 b = texelFetch(strand_data, offset + 1, 0);
-	vec4 c = texelFetch(strand_data, offset + 2, 0);
-	vec4 d = texelFetch(strand_data, offset + 3, 0);
-	vec4 e = texelFetch(strand_data, offset + 4, 0);
-	vec4 f = texelFetch(strand_data, offset + 5, 0);
+	vec2 a = read_texdata(offset);
+	vec2 b = read_texdata(offset + 1);
+	vec2 c = read_texdata(offset + 2);
+	vec2 d = read_texdata(offset + 3);
+	vec2 e = read_texdata(offset + 4);
+	vec2 f = read_texdata(offset + 5);
 
 	parent_index = ivec4(floatBitsToInt(a.rg), floatBitsToInt(b.rg));
 	parent_weight = vec4(c.rg, d.rg);
@@ -168,4 +174,4 @@ void hair_fiber_get_vertex(int fiber_index, float curve_param, mat4 ModelViewMat
 #endif
 }
 
-#endif /*HAIR_SHADER*/
+#endif /*HAIR_SHADER_FIBERS*/
diff --git a/source/blender/draw/intern/draw_cache_impl_strands.c b/source/blender/draw/intern/draw_cache_impl_strands.c
index bf3f8b02365..2d57d7e20ac 100644
--- a/source/blender/draw/intern/draw_cache_impl_strands.c
+++ b/source/blender/draw/intern/draw_cache_impl_strands.c
@@ -40,6 +40,7 @@
 #include "BKE_editstrands.h"
 
 #include "GPU_batch.h"
+#include "GPU_extensions.h"
 #include "GPU_texture.h"
 
 #include "draw_common.h"
@@ -163,7 +164,8 @@ static void editstrands_batch_cache_clear_hair(BMEditStrands *es)
 			buffer->fiber_start = 0;
 			buffer->strand_map_start = 0;
 			buffer->strand_vertex_start = 0;
-			buffer->size = 0;
+			buffer->width = 0;
+			buffer->height = 0;
 		}
 	}
 }
@@ -447,17 +449,26 @@ static void editstrands_batch_cache_ensure_hair_fibers(BMEditStrands *es, Strand
 static void editstrands_batch_cache_ensure_hair_fiber_texbuffer(BMEditStrands *es, StrandsBatchCache *cache, bool UNUSED(use_ribbons))
 {
 	DRWHairFiberTextureBuffer *buffer = &cache->hair.texbuffer;
+	static const int elemsize = 8;
+	const int width = GPU_max_texture_size();
+	const int align = width * elemsize;
 	
-	void *data;
 	// Offsets in bytes
 	int b_size, b_strand_map_start, b_strand_vertex_start, b_fiber_start;
-	BKE_editstrands_hair_get_texture_buffer(es, &data, &b_size,
-	                                        &b_strand_map_start, &b_strand_vertex_start, &b_fiber_start);
+	BKE_editstrands_hair_get_texture_buffer_size(es, &b_size, 
+	        &b_strand_map_start, &b_strand_vertex_start, &b_fiber_start);
+	// Pad for alignment
+	b_size += align - b_size % align;
 	
-	buffer->data = data;
 	// Convert to element size as texture offsets
-	static const int elemsize = 8;
-	buffer->size = b_size / elemsize;
+	const int size = b_size / elemsize;
+	const int height = size / width;
+	
+	buffer->data = MEM_mallocN(b_size, "hair fiber texture buffer");
+	BKE_editstrands_hair_get_texture_buffer(es, buffer->data);
+	
+	buffer->width = width;
+	buffer->height = height;
 	buffer->strand_map_start = b_strand_map_start / elemsize;
 	buffer->strand_vertex_start = b_strand_vertex_start / elemsize;
 	buffer->fiber_start = b_fiber_start / elemsize;
diff --git a/source/blender/draw/intern/draw_common.h b/source/blender/draw/intern/draw_common.h
index b7b591da918..c9f3629dc18 100644
--- a/source/blender/draw/intern/draw_common.h
+++ b/source/blender/draw/intern/draw_common.h
@@ -29,7 +29,9 @@
 struct DRWPass;
 struct DRWShadingGroup;
 struct Gwn_Batch;
+struct GPUTexture;
 struct Object;
+struct Scene;
 struct SceneLayer;
 
 /* Used as ubo but colors can be directly referenced as well */
@@ -134,7 +136,13 @@ typedef struct DRWHairFiberTextureBuffer {
 	int strand_map_start;
 	int strand_vertex_start;
 	int fiber_start;
-	int size;
+	int width;
+	int height;
 } DRWHairFiberTextureBuffer;
 
+const char* DRW_hair_shader_defines(void);
+
+void DRW_hair_shader_uniforms(struct DRWShadingGroup *shgrp, struct Scene *scene,
+                              struct GPUTexture **fibertex, const struct DRWHairFiberTextureBuffer *texbuffer);
+
 #endif /* __DRAW_COMMON_H__ */
diff --git a/source/blender/draw/intern/draw_hair.c b/source/blender/draw/intern/draw_hair.c
new file mode 100644
index 00000000000..0a357518381
--- /dev/null
+++ b/source/blender/draw/intern/draw_hair.c
@@ -0,0 +1,59 @@
+/*
+ * Copyright 2016, Blender Foundation.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 2
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin Street, Fifth Floor, Boston, MA 02110-1301, USA.
+ *
+ * Contributor(s): Blender Institute
+ *
+ */
+
+/** \file draw_hair.c
+ *  \ingroup draw
+ */
+
+#include "DNA_scene_types.h"
+
+#include "DRW_render.h"
+
+#include "BLI_utildefines.h"
+
+#include "GPU_extensions.h"
+#include "GPU_texture.h"
+
+#include "draw_common.h"
+
+const char* DRW_hair_shader_defines(void)
+{
+	static char str[256];
+	
+	BLI_snprintf(str, sizeof(str), "#define HAIR_SHADER_FIBERS\n#define HAIR_SHADER_TEX_WIDTH %d\n",
+	             GPU_max_texture_size());
+	
+	return str;
+}
+
+void DRW_hair_shader_uniforms(DRWShadingGroup *shgrp, Scene *scene,
+                              GPUTexture **fibertex, const DRWHairFiberTextureBuffer *texbuffer)
+{
+	const HairEditSettings *tsettings = &scene->toolsettings->hair_edit;
+	
+	DRW_shgroup_uniform_vec2(shgrp, "viewport_size", DRW_viewport_size_get(), 1);
+	DRW_shgroup_uniform_float(shgrp, "ribbon_width", &tsettings->hair_draw_size, 1);
+	
+	DRW_shgroup_uniform_buffer(shgrp, "strand_data", fibertex);
+	DRW_shgroup_uniform_int(shgrp, "strand_map_start", &texbuffer->strand_map_start, 1);
+	DRW_shgroup_uniform_int(shgrp, "strand_vertex_start", &texbuffer->strand_vertex_start, 1);
+	DRW_shgroup_uniform_int(shgrp, "fiber_start", &texbuffer->fiber_start, 1);
+}