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[Impeller] Remove the y_coord_scale Y-flip plumbing #187224

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Merged
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May 29, 2026
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[Impeller] Remove the y_coord_scale Y-flip plumbing #187224

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0ef9e6f
[Impeller] Remove the y_coord_scale Y-flip plumbing
bdero May 28, 2026
93be1fc
[Impeller] clang-format gradient shaders + update malioc baseline
bdero May 28, 2026
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1 change: 0 additions & 1 deletion engine/src/flutter/impeller/compiler/shader_lib/impeller/BUILD.gn
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Expand Up @@ -9,7 +9,6 @@ copy("impeller") {
"color.glsl",
"conical_gradient_uniform_fill.glsl",
"constants.glsl",
"conversions.glsl",
"dithering.glsl",
"external_texture_oes.glsl",
"gaussian.glsl",
Expand Down
13 changes: 5 additions & 8 deletions engine/src/flutter/impeller/compiler/shader_lib/impeller/conical_gradient_fill.glsl
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Expand Up @@ -14,7 +14,6 @@ uniform FragInfo {
float radius;
float tile_mode;
vec4 decal_border_color;
float texture_sampler_y_coord_scale;
float alpha;
vec2 half_texel;
vec2 focus;
Expand All @@ -28,13 +27,11 @@ vec4 DoConicalGradientTextureFill(vec2 res) {
}

float t = res.x;
vec4 result =
IPSampleLinearWithTileMode(texture_sampler, //
vec2(t, 0.5), //
frag_info.texture_sampler_y_coord_scale, //
frag_info.half_texel, //
frag_info.tile_mode, //
frag_info.decal_border_color);
vec4 result = IPSampleLinearWithTileMode(texture_sampler, //
vec2(t, 0.5), //
frag_info.half_texel, //
frag_info.tile_mode, //
frag_info.decal_border_color);
result = IPPremultiply(result) * frag_info.alpha;
return result;
}
Expand Down
15 changes: 0 additions & 15 deletions engine/src/flutter/impeller/compiler/shader_lib/impeller/conversions.glsl
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This file was deleted.

28 changes: 7 additions & 21 deletions engine/src/flutter/impeller/compiler/shader_lib/impeller/texture.glsl
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Expand Up @@ -6,37 +6,25 @@
#define TEXTURE_GLSL_

#include <impeller/branching.glsl>
#include <impeller/conversions.glsl>
#include <impeller/tile_mode.glsl>
#include <impeller/types.glsl>

/// Sample from a texture.
///
/// If `y_coord_scale` < 0.0, the Y coordinate is flipped. This is useful
/// for Impeller graphics backends that use a flipped framebuffer coordinate
/// space.
///
/// A negative mip bias is applied to improve the sharpness of scaled down
/// images when mip sampling is enabled. See `kDefaultMipBias` for more detail.
vec4 IPSample(sampler2D texture_sampler, vec2 coords, float y_coord_scale) {
return texture(texture_sampler, IPRemapCoords(coords, y_coord_scale),
kDefaultMipBias);
vec4 IPSample(sampler2D texture_sampler, vec2 coords) {
return texture(texture_sampler, coords, kDefaultMipBias);
}

/// Sample from a texture.
///
/// If `y_coord_scale` < 0.0, the Y coordinate is flipped. This is useful
/// for Impeller graphics backends that use a flipped framebuffer coordinate
/// space.
/// The range of `coords` will be mapped from [0, 1] to [half_texel, 1 -
/// half_texel]
vec4 IPSampleLinear(sampler2D texture_sampler,
vec2 coords,
float y_coord_scale,
vec2 half_texel) {
vec4 IPSampleLinear(sampler2D texture_sampler, vec2 coords, vec2 half_texel) {
coords.x = mix(half_texel.x, 1 - half_texel.x, coords.x);
coords.y = mix(half_texel.y, 1 - half_texel.y, coords.y);
return IPSample(texture_sampler, coords, y_coord_scale);
return IPSample(texture_sampler, coords);
}

/// Remap a float using a tiling mode.
Expand Down Expand Up @@ -106,7 +94,6 @@ f16vec4 IPHalfSampleWithTileMode(f16sampler2D tex,
/// half_texel]
vec4 IPSampleLinearWithTileMode(sampler2D tex,
vec2 coords,
float y_coord_scale,
vec2 half_texel,
float x_tile_mode,
float y_tile_mode,
Expand All @@ -117,7 +104,7 @@ vec4 IPSampleLinearWithTileMode(sampler2D tex,
}

return IPSampleLinear(tex, IPVec2Tile(coords, x_tile_mode, y_tile_mode),
y_coord_scale, half_texel);
half_texel);
}

/// Sample a texture with decal tile mode.
Expand Down Expand Up @@ -146,12 +133,11 @@ f16vec4 IPHalfSampleDecal(f16sampler2D texture_sampler, vec2 coords) {
/// half_texel]
vec4 IPSampleLinearWithTileMode(sampler2D tex,
vec2 coords,
float y_coord_scale,
vec2 half_texel,
float tile_mode,
vec4 decal_border_color) {
return IPSampleLinearWithTileMode(tex, coords, y_coord_scale, half_texel,
tile_mode, tile_mode, decal_border_color);
return IPSampleLinearWithTileMode(tex, coords, half_texel, tile_mode,
tile_mode, decal_border_color);
}

#endif
4 changes: 0 additions & 4 deletions engine/src/flutter/impeller/core/texture.cc
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Expand Up @@ -78,10 +78,6 @@ TextureCoordinateSystem Texture::GetCoordinateSystem() const {
return coordinate_system_;
}

Scalar Texture::GetYCoordScale() const {
return 1.0;
}

bool Texture::NeedsMipmapGeneration() const {
return !mipmap_generated_ && desc_.mip_count > 1;
}
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/core/texture.h
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Expand Up @@ -58,8 +58,6 @@ class Texture {

TextureCoordinateSystem GetCoordinateSystem() const;

virtual Scalar GetYCoordScale() const;

/// Returns true if mipmaps have never been generated.
/// The contents of the mipmap may be out of date if the root texture has been
/// modified and the mipmaps hasn't been regenerated.
Expand Down
8 changes: 0 additions & 8 deletions engine/src/flutter/impeller/entity/contents/atlas_contents.cc
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Expand Up @@ -191,8 +191,6 @@ bool AtlasContents::Render(const ContentContext& renderer,

VS::FrameInfo frame_info;
frame_info.mvp = entity.GetShaderTransform(pass);
frame_info.texture_sampler_y_coord_scale =
geometry_->GetAtlas()->GetYCoordScale();

VS::BindFrameInfo(pass, data_host_buffer.EmplaceUniform(frame_info));

Expand Down Expand Up @@ -224,8 +222,6 @@ bool AtlasContents::Render(const ContentContext& renderer,
VS::FrameInfo frame_info;

FS::BindTextureSamplerDst(pass, geometry_->GetAtlas(), dst_sampler);
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frame_info.texture_sampler_y_coord_scale =
geometry_->GetAtlas()->GetYCoordScale();

frag_info.input_alpha_output_alpha_tmx_tmy =
Vector4(1.0, alpha_, static_cast<int>(Entity::TileMode::kDecal),
Expand Down Expand Up @@ -265,8 +261,6 @@ bool AtlasContents::Render(const ContentContext& renderer,
VUS::FrameInfo frame_info;
FS::FragInfo frag_info;

frame_info.texture_sampler_y_coord_scale =
geometry_->GetAtlas()->GetYCoordScale();
frame_info.mvp = entity.GetShaderTransform(pass);

frag_info.alpha = alpha_;
Expand Down Expand Up @@ -338,8 +332,6 @@ bool ColorFilterAtlasContents::Render(const ContentContext& renderer,
VS::FrameInfo frame_info;

FS::BindInputTexture(pass, geometry_->GetAtlas(), dst_sampler);
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frame_info.texture_sampler_y_coord_scale =
geometry_->GetAtlas()->GetYCoordScale();

frag_info.input_alpha = 1;
frag_info.output_alpha = alpha_;
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/conical_gradient_contents.cc
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Expand Up @@ -220,8 +220,6 @@ bool ConicalGradientContents::RenderTexture(const ContentContext& renderer,
frag_info.radius = radius_;
frag_info.tile_mode = static_cast<Scalar>(tile_mode_);
frag_info.decal_border_color = decal_border_color_;
frag_info.texture_sampler_y_coord_scale =
gradient_texture->GetYCoordScale();
frag_info.alpha =
GetOpacityFactor() *
GetGeometry()->ComputeAlphaCoverage(entity.GetTransform());
Expand Down
10 changes: 0 additions & 10 deletions engine/src/flutter/impeller/entity/contents/filters/blend_filter_contents.cc
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Expand Up @@ -203,7 +203,6 @@ static std::optional<Entity> AdvancedBlend(
renderer.GetContext()->GetSamplerLibrary()->GetSampler(
dst_snapshot->sampler_descriptor);
FS::BindTextureSamplerDst(pass, dst_snapshot->texture, dst_sampler);
frame_info.dst_y_coord_scale = dst_snapshot->texture->GetYCoordScale();
blend_info.dst_input_alpha =
absorb_opacity == ColorFilterContents::AbsorbOpacity::kYes
? dst_snapshot->opacity
Expand All @@ -223,7 +222,6 @@ static std::optional<Entity> AdvancedBlend(
blend_info.color_factor = 0;
blend_info.src_input_alpha = src_snapshot->opacity;
FS::BindTextureSamplerSrc(pass, src_snapshot->texture, src_sampler);
frame_info.src_y_coord_scale = src_snapshot->texture->GetYCoordScale();
}
auto blend_uniform = data_host_buffer.EmplaceUniform(blend_info);
FS::BindBlendInfo(pass, blend_uniform);
Expand Down Expand Up @@ -370,7 +368,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundAdvancedBlend(
renderer.GetContext()->GetSamplerLibrary()->GetSampler(
dst_snapshot->sampler_descriptor);
FS::BindTextureSamplerDst(pass, dst_snapshot->texture, dst_sampler);
frame_info.dst_y_coord_scale = dst_snapshot->texture->GetYCoordScale();

frame_info.mvp = Entity::GetShaderTransform(
entity.GetShaderClipDepth(), pass,
Expand Down Expand Up @@ -472,8 +469,6 @@ std::optional<Entity> BlendFilterContents::CreateForegroundPorterDuffBlend(
renderer.GetContext()->GetSamplerLibrary()->GetSampler(
dst_snapshot->sampler_descriptor);
FS::BindTextureSamplerDst(pass, dst_snapshot->texture, dst_sampler);
frame_info.texture_sampler_y_coord_scale =
dst_snapshot->texture->GetYCoordScale();

frag_info.input_alpha_output_alpha_tmx_tmy =
Vector4(absorb_opacity == ColorFilterContents::AbsorbOpacity::kYes
Expand Down Expand Up @@ -573,8 +568,6 @@ static std::optional<Entity> PipelineBlend(
frame_info.mvp = pass.GetOrthographicTransform() *
Matrix::MakeTranslation(-subpass_coverage.GetOrigin()) *
input->transform;
frame_info.texture_sampler_y_coord_scale =
input->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.alpha =
Expand Down Expand Up @@ -704,8 +697,6 @@ std::optional<Entity> BlendFilterContents::CreateFramebufferAdvancedBlend(

VS::FrameInfo frame_info;
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
frame_info.texture_sampler_y_coord_scale =
dst_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.alpha = 1.0;
Expand Down Expand Up @@ -838,7 +829,6 @@ std::optional<Entity> BlendFilterContents::CreateFramebufferAdvancedBlend(
FS::BindTextureSamplerSrc(pass, src_texture, src_sampler);

frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
frame_info.src_y_coord_scale = src_texture->GetYCoordScale();
VS::BindFrameInfo(pass, data_host_buffer.EmplaceUniform(frame_info));

frag_info.src_input_alpha = 1.0;
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/border_mask_blur_filter_contents.cc
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Expand Up @@ -106,8 +106,6 @@ std::optional<Entity> BorderMaskBlurFilterContents::RenderFilter(

VS::FrameInfo frame_info;
frame_info.mvp = entity.GetShaderTransform(pass);
frame_info.texture_sampler_y_coord_scale =
input_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.sigma_uv = sigma.Abs() / input_snapshot->texture->GetSize();
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/color_matrix_filter_contents.cc
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Expand Up @@ -77,8 +77,6 @@ std::optional<Entity> ColorMatrixFilterContents::RenderFilter(
entity.GetShaderClipDepth(), pass,
entity.GetTransform() * input_snapshot->transform *
Matrix::MakeScale(Vector2(size)));
frame_info.texture_sampler_y_coord_scale =
input_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
const float* matrix = color_matrix.array;
Expand Down
45 changes: 3 additions & 42 deletions engine/src/flutter/impeller/entity/contents/filters/gaussian_blur_filter_contents.cc
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Expand Up @@ -207,38 +207,6 @@ Scalar FloorToDivisible(Scalar val, Scalar divisor) {
}
}

// If `y_coord_scale` < 0.0, the Y coordinate is flipped. This is useful
// for Impeller graphics backends that use a flipped framebuffer coordinate
// space.
//
// Both input and output quads are expected to be in the order of [Top-Left,
// Top-Right, Bottom-Left, Bottom-Right], a "Z-order" layout that conforms to
// the return format of Rect::GetPoints().
//
// See also: IPRemapCoords in convergions.glsl.
Quad RemapQuadCoords(const Quad& input, Scalar texture_sampler_y_coord_scale) {
if (texture_sampler_y_coord_scale < 0.0f) {
// The 4 points need reordering, because vertically flipping the quad:
//
// 0 → 1
// ↙
// 2 → 3
//
// should be flipped to:
//
// 2 → 3
// ↙
// 0 → 1
auto remap_point = [&](const Point& p) -> Point {
return Point(p.x, 1.0f - p.y);
};
return Quad{remap_point(input[2]), remap_point(input[3]),
remap_point(input[0]), remap_point(input[1])};
} else {
return input;
}
}

// Precomputes the line equation parameters for a quadrilateral's bounds.
//
// This function takes an array of 4 vertices and returns an array of 4
Expand Down Expand Up @@ -465,8 +433,6 @@ fml::StatusOr<RenderTarget> MakeDownsampleSubpass(

TextureFillVertexShader::FrameInfo frame_info;
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
frame_info.texture_sampler_y_coord_scale =
input_texture->GetYCoordScale();

TextureFillFragmentShader::FragInfo frag_info;
frag_info.alpha = 1.0;
Expand Down Expand Up @@ -522,9 +488,8 @@ fml::StatusOr<RenderTarget> MakeDownsampleSubpass(
renderer.GetDownsampleBoundedPipeline(pipeline_options));

TextureDownsampleBoundedFragmentShader::BoundInfo bound_info;
bound_info.quad_line_params = PrecomputeQuadLineParameters(
RemapQuadCoords(pass_args.uv_bounds.value(),
input_texture->GetYCoordScale()));
bound_info.quad_line_params =
PrecomputeQuadLineParameters(pass_args.uv_bounds.value());
TextureDownsampleBoundedFragmentShader::BindBoundInfo(
pass, data_host_buffer.EmplaceUniform(bound_info));
} else {
Expand All @@ -547,8 +512,6 @@ fml::StatusOr<RenderTarget> MakeDownsampleSubpass(

TextureFillVertexShader::FrameInfo frame_info;
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
frame_info.texture_sampler_y_coord_scale =
input_texture->GetYCoordScale();

TextureDownsampleFragmentShader::FragInfo frag_info;
frag_info.edge = edge;
Expand Down Expand Up @@ -609,9 +572,7 @@ fml::StatusOr<RenderTarget> MakeBlurSubpass(
ContentContext::SubpassCallback subpass_callback =
[&](const ContentContext& renderer, RenderPass& pass) {
GaussianBlurVertexShader::FrameInfo frame_info;
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1)),
frame_info.texture_sampler_y_coord_scale =
input_texture->GetYCoordScale();
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));

HostBuffer& data_host_buffer = renderer.GetTransientsDataBuffer();

Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/linear_to_srgb_filter_contents.cc
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Expand Up @@ -66,8 +66,6 @@ std::optional<Entity> LinearToSrgbFilterContents::RenderFilter(
entity.GetShaderClipDepth(), pass,
entity.GetTransform() * input_snapshot->transform *
Matrix::MakeScale(Vector2(size)));
frame_info.texture_sampler_y_coord_scale =
input_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.input_alpha =
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/morphology_filter_contents.cc
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Expand Up @@ -85,8 +85,6 @@ std::optional<Entity> DirectionalMorphologyFilterContents::RenderFilter(

VS::FrameInfo frame_info;
frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
frame_info.texture_sampler_y_coord_scale =
input_snapshot->texture->GetYCoordScale();

auto transform = entity.GetTransform() * effect_transform.Basis();
auto transformed_radius =
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/srgb_to_linear_filter_contents.cc
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Expand Up @@ -67,8 +67,6 @@ std::optional<Entity> SrgbToLinearFilterContents::RenderFilter(
entity.GetShaderClipDepth(), pass,
entity.GetTransform() * input_snapshot->transform *
Matrix::MakeScale(Vector2(size)));
frame_info.texture_sampler_y_coord_scale =
input_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.input_alpha =
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/filters/yuv_to_rgb_filter_contents.cc
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Expand Up @@ -96,8 +96,6 @@ std::optional<Entity> YUVToRGBFilterContents::RenderFilter(
entity.GetShaderClipDepth(), pass,
entity.GetTransform() * y_input_snapshot->transform *
Matrix::MakeScale(Vector2(size)));
frame_info.texture_sampler_y_coord_scale =
y_input_snapshot->texture->GetYCoordScale();

FS::FragInfo frag_info;
frag_info.yuv_color_space = static_cast<Scalar>(yuv_color_space);
Expand Down
1 change: 0 additions & 1 deletion engine/src/flutter/impeller/entity/contents/framebuffer_blend_contents.cc
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Expand Up @@ -138,7 +138,6 @@ bool FramebufferBlendContents::Render(const ContentContext& renderer,

frame_info.mvp = Entity::GetShaderTransform(entity.GetShaderClipDepth(), pass,
src_snapshot->transform);
frame_info.src_y_coord_scale = src_snapshot->texture->GetYCoordScale();
VS::BindFrameInfo(pass, data_host_buffer.EmplaceUniform(frame_info));

frag_info.src_input_alpha = src_snapshot->opacity;
Expand Down
2 changes: 0 additions & 2 deletions engine/src/flutter/impeller/entity/contents/linear_gradient_contents.cc
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Expand Up @@ -247,8 +247,6 @@ bool LinearGradientContents::RenderTexture(const ContentContext& renderer,
frag_info.end_point = end_point_;
frag_info.tile_mode = static_cast<Scalar>(tile_mode_);
frag_info.decal_border_color = decal_border_color_;
frag_info.texture_sampler_y_coord_scale =
gradient_texture->GetYCoordScale();
frag_info.alpha =
GetOpacityFactor() *
GetGeometry()->ComputeAlphaCoverage(entity.GetTransform());
Expand Down
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