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Fix T78956: banding artifacts of vertex colors in Cycles 

Byte colors must be encoded in sRGB and converted to linear on lookup,
to avoid precision loss.
This commit is contained in:
Brecht Van Lommel 2020-11-09 17:23:32 +01:00
parent dfe50ef2d8
commit ec6a9322e8
Notes: blender-bot 2023-02-14 04:46:12 +01:00 
Referenced by issue #78956, Subdivision Surface Modifier causes vertex color map to display a lot of banding in cycles. (Eevee is fine)
4 changed files with 25 additions and 18 deletions
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9
intern/cycles/blender/blender_mesh.cpp
View File

@ -346,7 +346,7 @@ static void attr_create_vertex_color(Scene *scene, Mesh *mesh, BL::Mesh &b_mesh,
for (int i = 0; i < n; i++) {
float4 color = get_float4(l->data[p->loop_start() + i].color());
/* Compress/encode vertex color using the sRGB curve. */
*(cdata++) = color_float4_to_uchar4(color_srgb_to_linear_v4(color));
*(cdata++) = color_float4_to_uchar4(color);
}
}
}
@ -368,9 +368,10 @@ static void attr_create_vertex_color(Scene *scene, Mesh *mesh, BL::Mesh &b_mesh,
float4 c3 = get_float4(l->data[li[2]].color());
/* Compress/encode vertex color using the sRGB curve. */
cdata[0] = color_float4_to_uchar4(color_srgb_to_linear_v4(c1));
cdata[1] = color_float4_to_uchar4(color_srgb_to_linear_v4(c2));
cdata[2] = color_float4_to_uchar4(color_srgb_to_linear_v4(c3));
cdata[0] = color_float4_to_uchar4(c1);
cdata[1] = color_float4_to_uchar4(c2);
cdata[2] = color_float4_to_uchar4(c3);
cdata += 3;
}
}

3
intern/cycles/kernel/geom/geom_patch.h
View File

@ -405,7 +405,8 @@ ccl_device float4 patch_eval_uchar4(KernelGlobals *kg,
*dv = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
for (int i = 0; i < num_control; i++) {
float4 v = color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, offset + indices[i]));
float4 v = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, offset + indices[i])));
val += v * weights[i];
if (du)

19
intern/cycles/kernel/geom/geom_subd_triangle.h
View File

@ -581,14 +581,14 @@ ccl_device_noinline float4 subd_triangle_attribute_float4(KernelGlobals *kg,
int corners[4];
subd_triangle_patch_corners(kg, patch, corners);
float4 f0 = color_uchar4_to_float4(
kernel_tex_fetch(__attributes_uchar4, corners[0] + desc.offset));
float4 f1 = color_uchar4_to_float4(
kernel_tex_fetch(__attributes_uchar4, corners[1] + desc.offset));
float4 f2 = color_uchar4_to_float4(
kernel_tex_fetch(__attributes_uchar4, corners[2] + desc.offset));
float4 f3 = color_uchar4_to_float4(
kernel_tex_fetch(__attributes_uchar4, corners[3] + desc.offset));
float4 f0 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, corners[0] + desc.offset)));
float4 f1 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, corners[1] + desc.offset)));
float4 f2 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, corners[2] + desc.offset)));
float4 f3 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, corners[3] + desc.offset)));
if (subd_triangle_patch_num_corners(kg, patch) != 4) {
f1 = (f1 + f0) * 0.5f;
@ -614,7 +614,8 @@ ccl_device_noinline float4 subd_triangle_attribute_float4(KernelGlobals *kg,
if (dy)
*dy = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
return color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, desc.offset));
return color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, desc.offset)));
}
else {
if (dx)

12
intern/cycles/kernel/geom/geom_triangle.h
View File

@ -317,9 +317,12 @@ ccl_device float4 triangle_attribute_float4(KernelGlobals *kg,
if (desc.element == ATTR_ELEMENT_CORNER_BYTE) {
int tri = desc.offset + sd->prim * 3;
f0 = color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 0));
f1 = color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 1));
f2 = color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 2));
f0 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 0)));
f1 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 1)));
f2 = color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, tri + 2)));
}
else {
uint4 tri_vindex = kernel_tex_fetch(__tri_vindex, sd->prim);
@ -343,7 +346,8 @@ ccl_device float4 triangle_attribute_float4(KernelGlobals *kg,
if (dy)
*dy = make_float4(0.0f, 0.0f, 0.0f, 0.0f);
return color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, desc.offset));
return color_srgb_to_linear_v4(
color_uchar4_to_float4(kernel_tex_fetch(__attributes_uchar4, desc.offset)));
}
else {
if (dx)