[Impeller] Remove pendown trick for solid strokes (flutter#36611)

ndusart · Oct 5, 2022 · 8b3894a · 8b3894a
1 parent 4d49147
commit 8b3894a
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Showing 4 changed files with 17 additions and 22 deletions.
diff --git a/impeller/entity/contents/solid_stroke_contents.cc b/impeller/entity/contents/solid_stroke_contents.cc
@@ -121,7 +121,6 @@ static VertexBuffer CreateSolidStrokeVertices(
       // and the beginning of the new contour.
       vtx.position = polyline.points[contour_start_point_i - 1];
       vtx.normal = {};
-      vtx.pen_down = 0.0;
       // Append two transparent vertices when "picking up" the pen so that the
       // triangle drawn when moving to the beginning of the new contour will
       // have zero volume. This is necessary because strokes with a transparent
@@ -134,7 +133,6 @@ static VertexBuffer CreateSolidStrokeVertices(
       // so that the next appended vertex will create a triangle with zero
       // volume.
       vtx_builder.AppendVertex(vtx);
-      vtx.pen_down = 1.0;
       vtx_builder.AppendVertex(vtx);
     }
 
@@ -150,7 +148,6 @@ static VertexBuffer CreateSolidStrokeVertices(
       if (point_i > contour_start_point_i) {
         // Generate line rect.
         vtx.position = polyline.points[point_i - 1];
-        vtx.pen_down = 1.0;
         vtx.normal = normal;
         vtx_builder.AppendVertex(vtx);
         vtx.normal = -normal;
@@ -271,7 +268,6 @@ void SolidStrokeContents::SetStrokeCap(Cap cap) {
                      const SmoothingApproximation& smoothing) {
         SolidStrokeVertexShader::PerVertexData vtx;
         vtx.position = position;
-        vtx.pen_down = 1.0;
 
         Point forward(normal.y, -normal.x);
 
@@ -299,7 +295,6 @@ void SolidStrokeContents::SetStrokeCap(Cap cap) {
                      const SmoothingApproximation& smoothing) {
         SolidStrokeVertexShader::PerVertexData vtx;
         vtx.position = position;
-        vtx.pen_down = 1.0;
 
         Point forward(normal.y, -normal.x);
 
@@ -327,7 +322,6 @@ static Scalar CreateBevelAndGetDirection(
     const Point& end_normal) {
   SolidStrokeVertexShader::PerVertexData vtx;
   vtx.position = position;
-  vtx.pen_down = 1.0;
   vtx.normal = {};
   vtx_builder.AppendVertex(vtx);
 
@@ -377,7 +371,6 @@ void SolidStrokeContents::SetStrokeJoin(Join join) {
         // Outer miter point.
         SolidStrokeVertexShader::PerVertexData vtx;
         vtx.position = position;
-        vtx.pen_down = 1.0;
         vtx.normal = miter_point * dir;
         vtx_builder.AppendVertex(vtx);
       };
@@ -411,7 +404,6 @@ void SolidStrokeContents::SetStrokeJoin(Join join) {
 
         SolidStrokeVertexShader::PerVertexData vtx;
         vtx.position = position;
-        vtx.pen_down = 1.0;
         for (const auto& point : arc_points) {
           vtx.normal = point * dir;
           vtx_builder.AppendVertex(vtx);

diff --git a/impeller/entity/entity_unittests.cc b/impeller/entity/entity_unittests.cc
@@ -203,13 +203,22 @@ TEST_P(EntityTest, ThreeStrokesInOnePath) {
 
 TEST_P(EntityTest, TriangleInsideASquare) {
   auto callback = [&](ContentContext& context, RenderPass& pass) {
-    Point a = IMPELLER_PLAYGROUND_POINT(Point(10, 10), 20, Color::White());
-    Point b = IMPELLER_PLAYGROUND_POINT(Point(210, 10), 20, Color::White());
-    Point c = IMPELLER_PLAYGROUND_POINT(Point(210, 210), 20, Color::White());
-    Point d = IMPELLER_PLAYGROUND_POINT(Point(10, 210), 20, Color::White());
-    Point e = IMPELLER_PLAYGROUND_POINT(Point(50, 50), 20, Color::White());
-    Point f = IMPELLER_PLAYGROUND_POINT(Point(100, 50), 20, Color::White());
-    Point g = IMPELLER_PLAYGROUND_POINT(Point(50, 150), 20, Color::White());
+    Point offset(100, 100);
+
+    Point a =
+        IMPELLER_PLAYGROUND_POINT(Point(10, 10) + offset, 20, Color::White());
+    Point b =
+        IMPELLER_PLAYGROUND_POINT(Point(210, 10) + offset, 20, Color::White());
+    Point c =
+        IMPELLER_PLAYGROUND_POINT(Point(210, 210) + offset, 20, Color::White());
+    Point d =
+        IMPELLER_PLAYGROUND_POINT(Point(10, 210) + offset, 20, Color::White());
+    Point e =
+        IMPELLER_PLAYGROUND_POINT(Point(50, 50) + offset, 20, Color::White());
+    Point f =
+        IMPELLER_PLAYGROUND_POINT(Point(100, 50) + offset, 20, Color::White());
+    Point g =
+        IMPELLER_PLAYGROUND_POINT(Point(50, 150) + offset, 20, Color::White());
     Path path = PathBuilder{}
                     .MoveTo(a)
                     .LineTo(b)

diff --git a/impeller/entity/shaders/solid_stroke.frag b/impeller/entity/shaders/solid_stroke.frag
@@ -7,10 +7,8 @@ uniform FragInfo {
 }
 frag_info;
 
-in float v_pen_down;
-
 out vec4 frag_color;
 
 void main() {
-  frag_color = frag_info.color * floor(v_pen_down);
+  frag_color = frag_info.color;
 }
diff --git a/impeller/entity/shaders/solid_stroke.vert b/impeller/entity/shaders/solid_stroke.vert
@@ -10,13 +10,9 @@ vert_info;
 
 in vec2 position;
 in vec2 normal;
-in float pen_down;
-
-out float v_pen_down;
 
 void main() {
   // Push one vertex by the half stroke size along the normal vector.
   vec2 offset = normal * vec2(vert_info.size * 0.5);
   gl_Position = vert_info.mvp * vec4(position + offset, 0.0, 1.0);
-  v_pen_down = pen_down;
 }