Intersection work in progress

Review URL: https://codereview.appspot.com/5576043

git-svn-id: http://skia.googlecode.com/svn/trunk@3087 2bbb7eff-a529-9590-31e7-b0007b416f81

1 files changed, 39 insertions, 0 deletions

diff --git a/experimental/Intersection/CubicParameterization_TestUtility.cpp b/experimental/Intersection/CubicParameterization_TestUtility.cpp
new file mode 100644
index 0000000000..2423a7cd5e
--- /dev/null
+++ b/experimental/Intersection/CubicParameterization_TestUtility.cpp
@@ -0,0 +1,39 @@
+// included by CubicParameterization.cpp
+// accesses internal functions to validate parameterized coefficients
+
+static void parameter_coeffs(const Cubic& cubic, double coeffs[coeff_count]) {
+    double ax, bx, cx, dx;
+    if (try_alt)
+        alt_set_abcd(&cubic[0].x, ax, bx, cx, dx);
+    else
+        set_abcd(&cubic[0].x, ax, bx, cx, dx);
+    double ay, by, cy, dy;
+    if (try_alt)
+        alt_set_abcd(&cubic[0].y, ay, by, cy, dy);
+    else
+        set_abcd(&cubic[0].y, ay, by, cy, dy);
+    calc_ABCD(ax, ay, coeffs);
+    if (!try_alt) calc_bc(dx, bx, cx);
+    if (!try_alt) calc_bc(dy, by, cy);
+    for (int index = xx_coeff; index < coeff_count; ++index) {
+        int procIndex = index - xx_coeff;
+        coeffs[index] = (*calc_proc[procIndex])(ax, bx, cx, dx, ay, by, cy, dy);
+    }
+}
+
+bool point_on_parameterized_curve(const Cubic& cubic, const _Point& point) {
+    double coeffs[coeff_count];
+    parameter_coeffs(cubic, coeffs);
+    double xxx = coeffs[xxx_coeff] * point.x * point.x * point.x;
+    double xxy = coeffs[xxy_coeff] * point.x * point.x * point.y;
+    double xyy = coeffs[xyy_coeff] * point.x * point.y * point.y;
+    double yyy = coeffs[yyy_coeff] * point.y * point.y * point.y;
+    double  xx = coeffs[ xx_coeff] * point.x * point.x;
+    double  xy = coeffs[ xy_coeff] * point.x * point.y;
+    double  yy = coeffs[ yy_coeff] * point.y * point.y;
+    double   x = coeffs[  x_coeff] * point.x;
+    double   y = coeffs[  y_coeff] * point.y;
+    double   c = coeffs[  c_coeff];
+    double sum = xxx + xxy + xyy + yyy + xx + xy + yy + x + y + c;
+    return approximately_zero(sum);
+}