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[Impeller] Switch to nearest sampling for the text atlas (flutter/engine#39104)

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This commit is contained in:
Brandon DeRosier
2023-01-24 16:00:37 -08:00
committed by GitHub
parent de54114b00
commit bc595eefcf
3 changed files with 11 additions and 9 deletions
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10
engine/src/flutter/impeller/entity/contents/text_contents.cc
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@@ -78,8 +78,8 @@ static bool CommonRender(
VS::BindFrameInfo(cmd, pass.GetTransientsBuffer().EmplaceUniform(frame_info));
SamplerDescriptor sampler_desc;
sampler_desc.min_filter = MinMagFilter::kLinear;
sampler_desc.mag_filter = MinMagFilter::kLinear;
sampler_desc.min_filter = MinMagFilter::kNearest;
sampler_desc.mag_filter = MinMagFilter::kNearest;
sampler_desc.mip_filter = MipFilter::kNone;
typename FS::FragInfo frag_info;
@@ -146,10 +146,10 @@ static bool CommonRender(
for (const auto& point : unit_points) {
typename VS::PerVertexData vtx;
vtx.unit_position = point;
vtx.destination_position = offset_glyph_position + Point(0.5, 0.5);
vtx.destination_position = offset_glyph_position;
vtx.destination_size = Point(glyph_position.glyph.bounds.size);
vtx.source_position = atlas_position + Point(0.5, 0.5);
vtx.source_glyph_size = atlas_glyph_size - Point(1.0, 1.0);
vtx.source_position = atlas_position;
vtx.source_glyph_size = atlas_glyph_size;
if constexpr (std::is_same_v<TPipeline, GlyphAtlasPipeline>) {
vtx.has_color =
glyph_position.glyph.type == Glyph::Type::kBitmap ? 1.0 : 0.0;

7
engine/src/flutter/impeller/entity/shaders/glyph_atlas.frag
View File

@@ -21,13 +21,14 @@ out vec4 frag_color;
void main() {
vec2 uv_size = v_source_glyph_size / frag_info.atlas_size;
vec2 offset = v_source_position / frag_info.atlas_size;
vec2 uv_position = v_source_position / frag_info.atlas_size;
if (v_has_color == 1.0) {
frag_color =
texture(glyph_atlas_sampler, v_unit_position * uv_size + offset);
texture(glyph_atlas_sampler, v_unit_position * uv_size + uv_position);
} else {
frag_color =
texture(glyph_atlas_sampler, v_unit_position * uv_size + offset).aaaa *
texture(glyph_atlas_sampler, v_unit_position * uv_size + uv_position)
.aaaa *
frag_info.text_color;
}
}

3
engine/src/flutter/impeller/entity/shaders/glyph_atlas.vert
View File

@@ -26,7 +26,8 @@ void main() {
gl_Position = IPPositionForGlyphPosition(
frame_info.mvp, unit_position, destination_position, destination_size);
v_unit_position = unit_position;
v_source_position = source_position;
// Pixel snap the source (sampling) start position.
v_source_position = round(source_position);
v_source_glyph_size = source_glyph_size;
v_has_color = has_color;
}