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ImDrawList: added AddBezier(), PathBezierTo() for cubic bezier curves (#311)

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ocornut
2015-08-28 13:18:34 +01:00
parent e58f99179a
commit 80ad773c87
4 changed files with 65 additions and 5 deletions
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50
imgui_draw.cpp
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@@ -639,6 +639,56 @@ void ImDrawList::PathArcTo(const ImVec2& centre, float radius, float amin, float
}
}
static void PathBezierToCasteljau(ImVector<ImVec2>* path, float x1, float y1, float x2, float y2, float x3, float y3, float x4, float y4, float tess_tol, int level)
{
float dx = x4 - x1;
float dy = y4 - y1;
float d2 = ((x2 - x4) * dy - (y2 - y4) * dx);
float d3 = ((x3 - x4) * dy - (y3 - y4) * dx);
d2 = (d2 >= 0) ? d2 : -d2;
d3 = (d3 >= 0) ? d3 : -d3;
if ((d2+d3) * (d2+d3) < tess_tol * (dx*dx + dy*dy))
{
path->push_back(ImVec2(x4, y4));
}
else if (level < 10)
{
float x12 = (x1+x2)*0.5f, y12 = (y1+y2)*0.5f;
float x23 = (x2+x3)*0.5f, y23 = (y2+y3)*0.5f;
float x34 = (x3+x4)*0.5f, y34 = (y3+y4)*0.5f;
float x123 = (x12+x23)*0.5f, y123 = (y12+y23)*0.5f;
float x234 = (x23+x34)*0.5f, y234 = (y23+y34)*0.5f;
float x1234 = (x123+x234)*0.5f, y1234 = (y123+y234)*0.5f;
PathBezierToCasteljau(path, x1,y1, x12,y12, x123,y123, x1234,y1234, tess_tol, level+1);
PathBezierToCasteljau(path, x1234,y1234, x234,y234, x34,y34, x4,y4, tess_tol, level+1);
}
}
void ImDrawList::PathBezierTo(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, int num_segments)
{
PathLineToMergeDuplicate(p1);
if (num_segments == 0)
{
// Auto-tessellated
PathBezierToCasteljau(&_Path, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y, GImGui->Style.CurveTessellationTol, 0);
}
else
{
float t_step = 1.0f / (float)num_segments;
for (int i_step = 1; i_step <= num_segments; i_step++)
{
float t = t_step * i_step;
float u = 1.0f - t;
float w1 = u*u*u;
float w2 = 3*u*u*t;
float w3 = 3*u*t*t;
float w4 = t*t*t;
_Path.push_back(ImVec2(w1*p1.x + w2*p2.x + w3*p3.x + w4*p4.x, w1*p1.y + w2*p2.y + w3*p3.y + w4*p4.y));
}
}
}
void ImDrawList::PathRect(const ImVec2& a, const ImVec2& b, float rounding, int rounding_corners)
{
float r = rounding;