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Grease Pencil: Remove minimum thickness clamping

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This removes the minimum thickness clamping in the shader.
The reason why this was clamped in the first place was to reduce
aliasing artifacts. With the new super sampling method for
rendering, this should no longer be an issue.

Note: This can break visual compatibility, but the previous radii
were arguably "wrong". This essentially fixes this and renders
the strokes with the actual radii from the attribute.
Previous files that might have relied on the clamping will have
to be updated.

Pull Request: https://projects.blender.org/blender/blender/pulls/138119
This commit is contained in:
Falk David
2025-04-29 12:46:48 +02:00
committed by Falk David
parent d4986be082
commit 1d6f313995
1 changed files with 2 additions and 19 deletions
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21
source/blender/draw/intern/shaders/draw_grease_pencil_lib.glsl
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@@ -79,30 +79,12 @@ float gpencil_stroke_thickness_modulate(float thickness, float4 ndc_pos, float4
/* Modify stroke thickness by object scale. */
thickness = length(to_float3x3(drw_modelmat()) * float3(thickness * M_SQRT1_3));
/* For compatibility, thickness has to be clamped after being multiplied by this factor.
* This clamping was introduced to reduce aliasing issue by instead fading the lines alpha at
* smaller radii. This can be removed in major release if compatibility is not a concern. */
const float legacy_radius_conversion_factor = 2000.0f;
thickness *= legacy_radius_conversion_factor;
thickness = max(1.0f, thickness);
thickness /= legacy_radius_conversion_factor;
/* World space point size. */
thickness *= drw_view().winmat[1][1] * viewport_res.y;
return thickness;
}
float gpencil_clamp_small_stroke_thickness(float thickness, float4 ndc_pos)
{
/* To avoid aliasing artifacts, we clamp the line thickness and
* reduce its opacity in the fragment shader. */
float min_thickness = ndc_pos.w * 1.3f;
thickness = max(min_thickness, thickness);
return thickness;
}
#ifdef GPU_VERTEX_SHADER
int gpencil_stroke_point_id()
@@ -253,7 +235,8 @@ float4 gpencil_vertex(float4 viewport_res,
float thickness = abs((use_curr) ? thickness1 : thickness2);
thickness = gpencil_stroke_thickness_modulate(thickness, out_ndc, viewport_res);
float clamped_thickness = gpencil_clamp_small_stroke_thickness(thickness, out_ndc);
/* The radius attribute can have negative values. Make sure that it's not negative by clamping to 0. */
float clamped_thickness = max(0.0f, thickness);
out_uv = float2(x, y) * 0.5f + 0.5f;
out_hardness = gpencil_decode_hardness(use_curr ? hardness1 : hardness2);