path rasterization started with opengl

1 files changed, 23 insertions, 81 deletions

diff --git a/my_imgui_internal_widgets.cpp b/my_imgui_internal_widgets.cpp
index c654e36..705b898 100644
--- a/my_imgui_internal_widgets.cpp
+++ b/my_imgui_internal_widgets.cpp
@@ -164,95 +164,44 @@ bool ImGui::TestLine(ImVec2 p0, ImVec2 p1)
     return Toggle;
 }
 
-// Slightly modified version of the bezier closest point lookup code that
-// additionally outputs the ratio of the closest point along the curve for use
-// in constructing the handles of new points.
+// Currently not used anywhere outside of debug UI. I'll keep it in case
+// there's a place where doing this operation in UI space is useful. Note that
+// the version of this function in bezier.cpp differs in precision by about
+// 0.001.
 
-
-// The ratio here is just the dot product divided by the squared length.
-ImVec2 ImLineClosestPoint2(const ImVec2& a, const ImVec2& b, const ImVec2& p, float& ratio)
+ImVec2 ImGui::RatioToPoint(ImVec2 a, ImVec2 b, float ratio)
 {
-    ImVec2 ap = p - a;
     ImVec2 ab_dir = b - a;
-    float dot = ap.x * ab_dir.x + ap.y * ab_dir.y;
-    if (dot < 0.0f) {
-        ratio = 0.0f;
-        return a;
-    }
     float ab_len_sqr = ab_dir.x * ab_dir.x + ab_dir.y * ab_dir.y;
-    if (dot > ab_len_sqr) {
-        ratio = 1.0f;
-        return b;
-    }
-    ratio = dot / ab_len_sqr;
+    float dot = ratio*ab_len_sqr;
     return a + ab_dir * dot / ab_len_sqr;
 }
 
-// Function to convert a ratio back into a point for the bezier handles.
-ImVec2 ImGui::RatioToPoint(const ImVec2& a, const ImVec2& b, float ratio)
+// Returns true when cursor is close to the curve but not too close to the
+// beginning/end points. Basically just a wrapper for that ClosestPoint
+// function.
+bool ImGui::BezierInteractive(ImVec2 p0, ImVec2 p1, ImVec2 p2, ImVec2 p3)
 {
-    ImVec2 ab_dir = b - a;
-    float ab_len_sqr = ab_dir.x * ab_dir.x + ab_dir.y * ab_dir.y;
-    float dot = ratio*ab_len_sqr;
-    return a + ab_dir * dot / ab_len_sqr;
-}
+    bool hovered = false;
 
+    ImGuiContext& g = *GImGui;
+    ImGuiWindow* window = GetCurrentWindow();
+    if (window->SkipItems)
+        return false;
 
-// Following the algorithm, we take the ratio from the _leftmost_ point in each
-// subdivision of the cubic spline until we're within tess_tol, and then we
-// interpolate it with the subdivision's rightmost point in the ClosestPoint call.
-// The pow(0.5, level) represents the ratio of the next subdivision's leftmost
-// point (AKA the rightmost point of the current subdivision).
+    ImVec2 point = ImBezierCubicClosestPointCasteljau(p0, p1, p2, p3, g.IO.MousePos, GetStyle().CurveTessellationTol);
 
-static void ImBezierCubicClosestPointCasteljauStep2(const ImVec2& p, ImVec2& p_closest, float ratio, float& r_closest, ImVec2& p_last, float& p_closest_dist2, 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))
-    {
-        ImVec2 p_current(x4, y4);
-        float added_ratio;
-        ImVec2 p_line = ImLineClosestPoint2(p_last, p_current, p, added_ratio);
-        float dist2 = ImLengthSqr(p - p_line);
-        if (dist2 < p_closest_dist2)
-        {
-            p_closest = p_line;
-            p_closest_dist2 = dist2;
-            r_closest = ratio + pow(0.5, level)*added_ratio;
-        }
-        p_last = p_current;
-    }
-    else if (level < 10)
+    if (abs(g.IO.MousePos.x - point.x) < 3 && abs(g.IO.MousePos.y - point.y) < 3 &&
+        abs(p0.x - point.x) > 3 && abs(p0.y - point.y) > 3 &&
+        abs(p1.x - point.x) > 3 && abs(p1.y - point.y) > 3)
     {
-        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;
-        ImBezierCubicClosestPointCasteljauStep2(p, p_closest, ratio, r_closest, p_last, p_closest_dist2, x1, y1, x12, y12, x123, y123, x1234, y1234, tess_tol, level + 1);
-        ImBezierCubicClosestPointCasteljauStep2(p, p_closest, ratio + pow(0.5, level+1), r_closest, p_last, p_closest_dist2, x1234, y1234, x234, y234, x34, y34, x4, y4, tess_tol, level + 1);
+        hovered = true;
     }
-}
 
-ImVec2 ImBezierCubicClosestPointCasteljau2(const ImVec2& p1, const ImVec2& p2, const ImVec2& p3, const ImVec2& p4, const ImVec2& p, float& ratio, float tess_tol)
-{
-    IM_ASSERT(tess_tol > 0.0f);
-    ImVec2 p_last = p1;
-    ImVec2 p_closest;
-    float p_closest_dist2 = FLT_MAX;
-    float r_closest;
-    ImBezierCubicClosestPointCasteljauStep2(p, p_closest, 0, r_closest, p_last, p_closest_dist2, p1.x, p1.y, p2.x, p2.y, p3.x, p3.y, p4.x, p4.y, tess_tol, 0);
-    ratio = r_closest;
-    return p_closest;
+    return hovered;
 }
 
-// Returns true when cursor is close to the curve but not too close to the beginning/end points.
-bool ImGui::BezierInteractive(ImVec2 p0, ImVec2 p1, ImVec2 p2, ImVec2 p3, float& ratio)
+bool ImGui::LineInteractive(ImVec2 p0, ImVec2 p1)
 {
     bool hovered = false;
 
@@ -261,21 +210,14 @@ bool ImGui::BezierInteractive(ImVec2 p0, ImVec2 p1, ImVec2 p2, ImVec2 p3, float&
     if (window->SkipItems)
         return false;
 
-    ImDrawList* draw_list = window->DrawList;
-    ImU32 col = ImGui::GetColorU32(ImGuiCol_ScrollbarGrab);
-
-    ImVec2 point = ImBezierCubicClosestPointCasteljau2(p0, p1, p2, p3, g.IO.MousePos, ratio, GetStyle().CurveTessellationTol);
-
+    ImVec2 point = ImLineClosestPoint(p0, p1, g.IO.MousePos);
 
     if (abs(g.IO.MousePos.x - point.x) < 3 && abs(g.IO.MousePos.y - point.y) < 3 &&
         abs(p0.x - point.x) > 3 && abs(p0.y - point.y) > 3 &&
         abs(p1.x - point.x) > 3 && abs(p1.y - point.y) > 3)
     {
-        col = GetColorU32(ImGuiCol_Button);
         hovered = true;
     }
 
-    draw_list->AddBezierCubic(p0, p1, p2, p3, col, 2.0f, 0);
-
     return hovered;
 }