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path: root/src/effects/SkRRectsGaussianEdgeShader.cpp
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Diffstat (limited to 'src/effects/SkRRectsGaussianEdgeShader.cpp')
-rw-r--r--src/effects/SkRRectsGaussianEdgeShader.cpp124
1 files changed, 87 insertions, 37 deletions
diff --git a/src/effects/SkRRectsGaussianEdgeShader.cpp b/src/effects/SkRRectsGaussianEdgeShader.cpp
index e7703f964a..3b1d5650c3 100644
--- a/src/effects/SkRRectsGaussianEdgeShader.cpp
+++ b/src/effects/SkRRectsGaussianEdgeShader.cpp
@@ -111,8 +111,9 @@ public:
const char* outputName,
const char indices[2]) { // how to access the params for the 2 rrects
- // positive distance is towards the center of the circle
- fragBuilder->codeAppendf("vec2 delta = %s.xy - %s.%s;",
+ // Positive distance is towards the center of the circle.
+ // Map all the cases to the lower right quadrant.
+ fragBuilder->codeAppendf("vec2 delta = abs(%s.xy - %s.%s);",
fragBuilder->fragmentPosition(), posName, indices);
switch (mode) {
@@ -126,44 +127,95 @@ public:
break;
case kRect_Mode:
fragBuilder->codeAppendf(
- "vec2 rectDist = vec2(1.0 - clamp((%s.%c - abs(delta.x))/%s, 0.0, 1.0),"
- "1.0 - clamp((%s.%c - abs(delta.y))/%s, 0.0, 1.0));",
+ "vec2 rectDist = vec2(1.0 - clamp((%s.%c - delta.x)/%s, 0.0, 1.0),"
+ "1.0 - clamp((%s.%c - delta.y)/%s, 0.0, 1.0));",
sizesName, indices[0], radName,
sizesName, indices[1], radName);
fragBuilder->codeAppendf("%s = clamp(1.0 - length(rectDist), 0.0, 1.0);",
outputName);
break;
case kSimpleCircular_Mode:
- // For the circular round rect we first compute the distance
- // to the rect. Then we compute a multiplier that is 1 if the
- // point is in one of the circular corners. We then compute the
- // distance from the corner and then use the multiplier to mask
- // between the two distances.
- fragBuilder->codeAppendf("float xDist = clamp((%s.%c - abs(delta.x))/%s,"
- "0.0, 1.0);",
+ // For the circular round rect we combine 2 distances:
+ // the fractional position from the corner inset point to the corner's circle
+ // the minimum perpendicular distance to the bounding rectangle
+ // The first distance is used when the pixel is inside the ice-cream-cone-shaped
+ // portion of a corner. The second is used everywhere else.
+ // This is intended to approximate the interpolation pattern if we had tessellated
+ // this geometry into a RRect outside and a rect inside.
+
+ //----------------
+ // rect distance computation
+ fragBuilder->codeAppendf("float xDist = (%s.%c - delta.x) / %s;",
sizesName, indices[0], radName);
- fragBuilder->codeAppendf("float yDist = clamp((%s.%c - abs(delta.y))/%s,"
- "0.0, 1.0);",
+ fragBuilder->codeAppendf("float yDist = (%s.%c - delta.y) / %s;",
sizesName, indices[1], radName);
- fragBuilder->codeAppend("float rectDist = min(xDist, yDist);");
-
- fragBuilder->codeAppendf("vec2 cornerCenter = %s.%s - %s.%s;",
- sizesName, indices, radiiName, indices);
- fragBuilder->codeAppend("delta = vec2(abs(delta.x) - cornerCenter.x,"
- "abs(delta.y) - cornerCenter.y);");
- fragBuilder->codeAppendf("xDist = %s.%c - abs(delta.x);", radiiName, indices[0]);
- fragBuilder->codeAppendf("yDist = %s.%c - abs(delta.y);", radiiName, indices[1]);
- fragBuilder->codeAppend("float cornerDist = min(xDist, yDist);");
- fragBuilder->codeAppend("float multiplier = step(0.0, cornerDist);");
-
- fragBuilder->codeAppendf("delta += %s.%s;", radiiName, indices);
-
- fragBuilder->codeAppendf("cornerDist = clamp((2.0 * %s.%c - length(delta))/%s,"
- "0.0, 1.0);",
- radiiName, indices[0], radName);
-
- fragBuilder->codeAppendf("%s = (multiplier * cornerDist) +"
- "((1.0-multiplier) * rectDist);",
+ fragBuilder->codeAppend("float rectDist = clamp(min(xDist, yDist), 0.0, 1.0);");
+
+ //----------------
+ // ice-cream-cone fractional distance computation
+
+ // When the blurRadius is larger than the corner radius we want to use it to
+ // compute the pointy end of the ice cream cone. If it smaller we just want to use
+ // the center of the corner's circle. When using the blurRadius the inset amount
+ // can't exceed the halfwidths of the RRect.
+ fragBuilder->codeAppendf("float insetDist = min(max(%s, %s.%c),min(%s.%c, %s.%c));",
+ radName, radiiName, indices[0],
+ sizesName, indices[0], sizesName, indices[1]);
+ // "maxValue" is a correction term for if the blurRadius is larger than the
+ // size of the RRect. In that case we don't want to go all the way to black.
+ fragBuilder->codeAppendf("float maxValue = insetDist/%s;", radName);
+
+ fragBuilder->codeAppendf("vec2 coneBottom = vec2(%s.%c - insetDist,"
+ "%s.%c - insetDist);",
+ sizesName, indices[0], sizesName, indices[1]);
+
+ fragBuilder->codeAppendf("vec2 cornerTop = vec2(%s.%c - %s.%c, %s.%c) -"
+ "coneBottom;",
+ sizesName, indices[0], radiiName, indices[0],
+ sizesName, indices[1]);
+ fragBuilder->codeAppendf("vec2 cornerRight = vec2(%s.%c, %s.%c - %s.%c) -"
+ "coneBottom;",
+ sizesName, indices[0],
+ sizesName, indices[1], radiiName, indices[1]);
+
+ fragBuilder->codeAppend("vec2 ptInConeSpace = delta - coneBottom;");
+ fragBuilder->codeAppend("float distToPtInConeSpace = length(ptInConeSpace);");
+
+ fragBuilder->codeAppend("float cross1 = ptInConeSpace.x * cornerTop.y -"
+ "ptInConeSpace.y * cornerTop.x;");
+ fragBuilder->codeAppend("float cross2 = -ptInConeSpace.x * cornerRight.y + "
+ "ptInConeSpace.y * cornerRight.x;");
+
+ fragBuilder->codeAppend("float inCone = step(0.0, cross1) * step(0.0, cross2);");
+
+ fragBuilder->codeAppendf("vec2 cornerCenterInConeSpace = vec2(insetDist - %s.%c);",
+ radiiName, indices[0]);
+
+ fragBuilder->codeAppend("vec2 connectingVec = ptInConeSpace -"
+ "cornerCenterInConeSpace;");
+ fragBuilder->codeAppend("ptInConeSpace = normalize(ptInConeSpace);");
+
+ // "a" (i.e., dot(ptInConeSpace, ptInConeSpace) should always be 1.0f since
+ // ptInConeSpace is now normalized
+ fragBuilder->codeAppend("float b = 2.0 * dot(ptInConeSpace, connectingVec);");
+ fragBuilder->codeAppendf("float c = dot(connectingVec, connectingVec) - "
+ "%s.%c * %s.%c;",
+ radiiName, indices[0], radiiName, indices[0]);
+
+ fragBuilder->codeAppend("float fourAC = 4*c;");
+ // This max prevents sqrt(-1) when outside the cone
+ fragBuilder->codeAppend("float bSq = max(b*b, fourAC);");
+
+ // lop off negative values that are outside the cone
+ fragBuilder->codeAppend("float coneDist = max(0.0, "
+ "0.5 * (-b + sqrt(bSq - fourAC)));");
+ // make the coneDist a fraction of how far it is from the edge to the cone's base
+ fragBuilder->codeAppend("coneDist = (maxValue*coneDist) /"
+ "(coneDist+distToPtInConeSpace);");
+ fragBuilder->codeAppend("coneDist = clamp(coneDist, 0.0, 1.0);");
+
+ //----------------
+ fragBuilder->codeAppendf("%s = (inCone * coneDist) + ((1.0-inCone) * rectDist);",
outputName);
break;
}
@@ -247,10 +299,8 @@ public:
// This is a bit of overkill since fX should equal fY for both round rects but it
// makes the shader code simpler.
pdman.set4f(fRadiiUni,
- 0.5f * first.getSimpleRadii().fX,
- 0.5f * first.getSimpleRadii().fY,
- 0.5f * second.getSimpleRadii().fX,
- 0.5f * second.getSimpleRadii().fY);
+ first.getSimpleRadii().fX, first.getSimpleRadii().fY,
+ second.getSimpleRadii().fX, second.getSimpleRadii().fY);
}
pdman.set1f(fRadiusUni, edgeFP.radius());
@@ -264,7 +314,7 @@ public:
// For circles we still upload both width & height to simplify things
GrGLSLProgramDataManager::UniformHandle fSizesUni;
- // The half corner radii of the two round rects (rx1/2, ry1/2, rx2/2, ry2/2)
+ // The corner radii of the two round rects (rx1, ry1, rx2, ry2)
// We upload both the x&y radii (although they are currently always the same) to make
// the indexing in the shader code simpler. In some future world we could also support
// non-circular corner round rects & ellipses.
generated by cgit v1.2.3 (git 2.39.1) at 2024-07-01 03:43:11 +0000