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.

2 files changed, 45 insertions, 59 deletions

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*/