Workbench: Rework hair support.

Now hairs are shaded properly in workbench and support texturing.

I also added a 10% random normal direction per hair to have a bit more
variation in the shading. This is hardcoded for now.

4 files changed, 83 insertions, 35 deletions

diff --git a/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
index 269911189fa..5f37490603d 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_deferred_composite_frag.glsl
@@ -47,7 +47,7 @@ void main()
 #ifdef NORMAL_VIEWPORT_PASS_ENABLED
 #ifdef WORKBENCH_ENCODE_NORMALS
 	vec3 normal_viewport = normal_decode(texelFetch(normalBuffer, texel, 0).rg);
-	if (diffuse_color.a == 1.0) {
+	if (diffuse_color.a == 0.0) {
 		normal_viewport = -normal_viewport;
 	}
 #else /* WORKBENCH_ENCODE_NORMALS */
@@ -81,9 +81,13 @@ void main()
 #endif /* V3D_LIGHTING_STUDIO */
 
 #ifdef V3D_SHADING_SHADOW
-	float shadow_mix = step(-shadowShift, dot(normal_viewport, world_data.light_direction_vs.xyz));
-	float light_multiplier;
-	light_multiplier = mix(lightMultiplier, shadowMultiplier, shadow_mix);
+	float light_factor = -dot(normal_viewport, world_data.light_direction_vs.xyz);
+	/* The step function might be ok for meshes but it's
+	 * clearly not the case for hairs. Do smoothstep in this case. */
+	float shadow_mix = (diffuse_color.a == 1.0 || diffuse_color.a == 0.0)
+	                        ? step(-shadowShift, -light_factor)
+	                        : smoothstep(1.0, shadowShift, light_factor);
+	float light_multiplier = mix(lightMultiplier, shadowMultiplier, shadow_mix);
 
 #else /* V3D_SHADING_SHADOW */
 	float light_multiplier = 1.0;
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
index 3f271ec439b..a9c84e11aa6 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_forward_transparent_accum_frag.glsl
@@ -39,20 +39,17 @@ void main()
 #endif
 
 #ifdef V3D_LIGHTING_STUDIO
-#ifdef STUDIOLIGHT_ORIENTATION_CAMERA
+#  ifdef STUDIOLIGHT_ORIENTATION_CAMERA
 	vec3 diffuse_light = get_camera_diffuse_light(world_data, normal_viewport);
-#endif
-#ifdef STUDIOLIGHT_ORIENTATION_WORLD
+#  endif
+#  ifdef STUDIOLIGHT_ORIENTATION_WORLD
 	vec3 normal_world = normalWorldMatrix * normal_viewport;
 	vec3 diffuse_light = get_world_diffuse_light(world_data, normal_world);
-#endif
-
+#  endif
 	vec3 shaded_color = diffuse_light * diffuse_color.rgb + specular_color;
-
-#else /* V3D_LIGHTING_STUDIO */
+#else
 	vec3 shaded_color = diffuse_color.rgb + specular_color;
-
-#endif /* V3D_LIGHTING_STUDIO */
+#endif
 
 	vec4 premultiplied = vec4(shaded_color.rgb * alpha, alpha);
 	transparentAccum = calculate_transparent_accum(premultiplied);
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_prepass_frag.glsl b/source/blender/draw/engines/workbench/shaders/workbench_prepass_frag.glsl
index c0f58271a8c..bc7741f853c 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_prepass_frag.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_prepass_frag.glsl
@@ -9,12 +9,17 @@ uniform sampler2D image;
 #endif
 
 #ifdef NORMAL_VIEWPORT_PASS_ENABLED
+in vec3 position_viewport;
 in vec3 normal_viewport;
 #endif /* NORMAL_VIEWPORT_PASS_ENABLED */
 #ifdef OB_TEXTURE
 in vec2 uv_interp;
 #endif /* OB_TEXTURE */
 
+#ifdef HAIR_SHADER
+flat in float hair_rand;
+#endif
+
 layout(location=0) out uint objectId;
 layout(location=1) out vec4 diffuseColor;
 layout(location=2) out vec4 specularColor;
@@ -35,23 +40,29 @@ void main()
 #ifdef OB_TEXTURE
 	diffuseColor = texture(image, uv_interp);
 #endif /* OB_TEXTURE */
+#ifdef HAIR_SHADER
+	float hair_color_variation = hair_rand * 0.1;
+	diffuseColor.rgb = clamp(diffuseColor.rgb - hair_color_variation, 0.0, 1.0);
+#endif
 
 #ifdef V3D_SHADING_SPECULAR_HIGHLIGHT
 	specularColor = vec4(material_data.specular_color.rgb, material_data.roughness);
+#ifdef HAIR_SHADER
+	specularColor.rgb = clamp(specularColor.rgb - hair_color_variation, 0.0, 1.0);
+#endif
 #endif
 
 #ifdef NORMAL_VIEWPORT_PASS_ENABLED
-	#ifdef WORKBENCH_ENCODE_NORMALS
-	if (!gl_FrontFacing) {
-		normalViewport = normal_encode(normalize(-normal_viewport));
-		diffuseColor.a = 1.0;
-	}
-	else {
-		normalViewport = normal_encode(normalize(normal_viewport));
-		diffuseColor.a = 0.0;
-	}
-	#else /* WORKBENCH_ENCODE_NORMALS */
-	normalViewport = normal_viewport;
-	#endif /* WORKBENCH_ENCODE_NORMALS */
+	vec3 n = (gl_FrontFacing) ? normal_viewport : -normal_viewport;
+	n = normalize(n);
+#  ifdef WORKBENCH_ENCODE_NORMALS
+	diffuseColor.a = float(gl_FrontFacing);
+	normalViewport = normal_encode(n);
+#  else /* WORKBENCH_ENCODE_NORMALS */
+	normalViewport = n;
+#  endif /* WORKBENCH_ENCODE_NORMALS */
+#  ifdef HAIR_SHADER
+	diffuseColor.a = 0.5;
+#  endif
 #endif /* NORMAL_VIEWPORT_PASS_ENABLED */
 }
diff --git a/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl b/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
index f2df117d897..7da9c2644fe 100644
--- a/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
+++ b/source/blender/draw/engines/workbench/shaders/workbench_prepass_vert.glsl
@@ -1,30 +1,66 @@
 uniform mat4 ModelViewProjectionMatrix;
-#ifdef NORMAL_VIEWPORT_PASS_ENABLED
+uniform mat4 ProjectionMatrix;
+uniform mat4 ViewProjectionMatrix;
+uniform mat4 ViewMatrixInverse;
 uniform mat3 NormalMatrix;
-#endif /* NORMAL_VIEWPORT_PASS_ENABLED */
 
+#ifndef HAIR_SHADER
 in vec3 pos;
-#ifdef NORMAL_VIEWPORT_PASS_ENABLED
 in vec3 nor;
-#endif /* NORMAL_VIEWPORT_PASS_ENABLED */
-#ifdef OB_TEXTURE
 in vec2 uv;
-#endif
+#else /* HAIR_SHADER */
+#  ifdef OB_TEXTURE
+uniform samplerBuffer u; /* active texture layer */
+#  endif
+flat out float hair_rand;
+#endif /* HAIR_SHADER */
 
 #ifdef NORMAL_VIEWPORT_PASS_ENABLED
 out vec3 normal_viewport;
-#endif /* NORMAL_VIEWPORT_PASS_ENABLED */
+#endif
 #ifdef OB_TEXTURE
 out vec2 uv_interp;
 #endif
 
+/* From http://libnoise.sourceforge.net/noisegen/index.html */
+float integer_noise(int n)
+{
+	n = (n >> 13) ^ n;
+	int nn = (n * (n * n * 60493 + 19990303) + 1376312589) & 0x7fffffff;
+	return (float(nn) / 1073741824.0);
+}
+
 void main()
 {
+#ifdef HAIR_SHADER
+#  ifdef OB_TEXTURE
+	vec2 uv = hair_get_customdata_vec2(u);
+#  endif
+	float time, thick_time, thickness;
+	vec3 pos, tan, binor;
+	hair_get_pos_tan_binor_time(
+	        (ProjectionMatrix[3][3] == 0.0),
+	        ViewMatrixInverse[3].xyz, ViewMatrixInverse[2].xyz,
+	        pos, tan, binor, time, thickness, thick_time);
+	/* To "simulate" anisotropic shading, randomize hair normal per strand. */
+	hair_rand = integer_noise(hair_get_strand_id());
+	tan = normalize(tan);
+	vec3 nor = normalize(cross(binor, tan));
+	nor = normalize(mix(nor, -tan, hair_rand * 0.10));
+	float cos_theta = (hair_rand*2.0 - 1.0) * 0.20;
+	float sin_theta = sqrt(max(0.0, 1.0f - cos_theta*cos_theta));
+	nor = nor * sin_theta + binor * cos_theta;
+	gl_Position = ViewProjectionMatrix * vec4(pos, 1.0);
+#else
+	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+#endif
 #ifdef OB_TEXTURE
 	uv_interp = uv;
 #endif
 #ifdef NORMAL_VIEWPORT_PASS_ENABLED
-	normal_viewport = normalize(NormalMatrix * nor);
-#endif /* NORMAL_VIEWPORT_PASS_ENABLED */
-	gl_Position = ModelViewProjectionMatrix * vec4(pos, 1.0);
+	normal_viewport = NormalMatrix * nor;
+#  ifndef HAIR_SHADER
+	normal_viewport = normalize(normal_viewport);
+#  endif
+#endif
 }