[impeller] move gaussian blur vertex uniforms to fragment uniforms (f…

…lutter#35201)

impeller/entity/contents/filters/gaussian_blur_filter_contents.cc

@@ -130,15 +130,18 @@ bool DirectionalGaussianBlurFilterContents::RenderFilter(
       blur_direction_ * blur_sigma_.sigma);
 
   VS::FrameInfo frame_info;
-  frame_info.texture_size = Point(input_snapshot->GetCoverage().value().size);
-  frame_info.blur_sigma = transformed_blur.GetLength();
-  frame_info.blur_radius = Radius{Sigma{frame_info.blur_sigma}}.radius;
-  frame_info.blur_direction = input_snapshot->transform.Invert()
-                                  .TransformDirection(transformed_blur)
-                                  .Normalize();
-  frame_info.src_factor = src_color_factor_;
-  frame_info.inner_blur_factor = inner_blur_factor_;
-  frame_info.outer_blur_factor = outer_blur_factor_;
+  frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
+
+  FS::FragInfo frag_info;
+  frag_info.blur_sigma = transformed_blur.GetLength();
+  frag_info.blur_radius = Radius{Sigma{frag_info.blur_sigma}}.radius;
+  frag_info.blur_direction = input_snapshot->transform.Invert()
+                                 .TransformDirection(transformed_blur)
+                                 .Normalize();
+  frag_info.src_factor = src_color_factor_;
+  frag_info.inner_blur_factor = inner_blur_factor_;
+  frag_info.outer_blur_factor = outer_blur_factor_;
+  frag_info.texture_size = Point(input_snapshot->GetCoverage().value().size);
 
   SamplerDescriptor sampler_desc;
   sampler_desc.min_filter = MinMagFilter::kLinear;
@@ -155,10 +158,8 @@ bool DirectionalGaussianBlurFilterContents::RenderFilter(
 
   FS::BindTextureSampler(cmd, input_snapshot->texture, sampler);
   FS::BindAlphaMaskSampler(cmd, source_snapshot->texture, sampler);
-
-  frame_info.mvp = Matrix::MakeOrthographic(ISize(1, 1));
-  auto uniform_view = host_buffer.EmplaceUniform(frame_info);
-  VS::BindFrameInfo(cmd, uniform_view);
+  VS::BindFrameInfo(cmd, host_buffer.EmplaceUniform(frame_info));
+  FS::BindFragInfo(cmd, host_buffer.EmplaceUniform(frag_info));
 
   return pass.AddCommand(cmd);
 }

impeller/entity/shaders/gaussian_blur.frag

@@ -14,31 +14,35 @@
 uniform sampler2D texture_sampler;
 uniform sampler2D alpha_mask_sampler;
 
+uniform FragInfo {
+  vec2 texture_size;
+  vec2 blur_direction;
+
+  float blur_sigma;
+  float blur_radius;
+  float src_factor;
+  float inner_blur_factor;
+  float outer_blur_factor;
+} frag_info;
+
 in vec2 v_texture_coords;
 in vec2 v_src_texture_coords;
-in vec2 v_texture_size;
-in vec2 v_blur_direction;
-in float v_blur_sigma;
-in float v_blur_radius;
-in float v_src_factor;
-in float v_inner_blur_factor;
-in float v_outer_blur_factor;
 
 out vec4 frag_color;
 
 const float kSqrtTwoPi = 2.50662827463;
 
 float Gaussian(float x) {
-  float variance = v_blur_sigma * v_blur_sigma;
-  return exp(-0.5 * x * x / variance) / (kSqrtTwoPi * v_blur_sigma);
+  float variance = frag_info.blur_sigma * frag_info.blur_sigma;
+  return exp(-0.5 * x * x / variance) / (kSqrtTwoPi * frag_info.blur_sigma);
 }
 
 void main() {
   vec4 total_color = vec4(0);
   float gaussian_integral = 0;
-  vec2 blur_uv_offset = v_blur_direction / v_texture_size;
+  vec2 blur_uv_offset = frag_info.blur_direction / frag_info.texture_size;
 
-  for (float i = -v_blur_radius; i <= v_blur_radius; i++) {
+  for (float i = -frag_info.blur_radius; i <= frag_info.blur_radius; i++) {
     float gaussian = Gaussian(i);
     gaussian_integral += gaussian;
     total_color +=
@@ -50,8 +54,8 @@ void main() {
 
   vec4 src_color =
       IPSampleClampToBorder(alpha_mask_sampler, v_src_texture_coords);
-  float blur_factor = v_inner_blur_factor * float(src_color.a > 0) +
-                      v_outer_blur_factor * float(src_color.a == 0);
+  float blur_factor = frag_info.inner_blur_factor * float(src_color.a > 0) +
+                      frag_info.outer_blur_factor * float(src_color.a == 0);
 
-  frag_color = blur_color * blur_factor + src_color * v_src_factor;
+  frag_color = blur_color * blur_factor + src_color * frag_info.src_factor;
 }

impeller/entity/shaders/gaussian_blur.vert

@@ -4,15 +4,6 @@
 
 uniform FrameInfo {
   mat4 mvp;
-  vec2 texture_size;
-
-  vec2 blur_direction;
-  float blur_sigma;
-  float blur_radius;
-
-  float src_factor;
-  float inner_blur_factor;
-  float outer_blur_factor;
 }
 frame_info;
 
@@ -22,23 +13,9 @@ in vec2 src_texture_coords;
 
 out vec2 v_texture_coords;
 out vec2 v_src_texture_coords;
-out vec2 v_texture_size;
-out vec2 v_blur_direction;
-out float v_blur_sigma;
-out float v_blur_radius;
-out float v_src_factor;
-out float v_inner_blur_factor;
-out float v_outer_blur_factor;
 
 void main() {
   gl_Position = frame_info.mvp * vec4(vertices, 0.0, 1.0);
   v_texture_coords = texture_coords;
   v_src_texture_coords = src_texture_coords;
-  v_texture_size = frame_info.texture_size;
-  v_blur_direction = frame_info.blur_direction;
-  v_blur_sigma = frame_info.blur_sigma;
-  v_blur_radius = frame_info.blur_radius;
-  v_src_factor = frame_info.src_factor;
-  v_inner_blur_factor = frame_info.inner_blur_factor;
-  v_outer_blur_factor = frame_info.outer_blur_factor;
 }