use the vertex output as a buffer

ocornut · May 30, 2018 · 6e89be6 · 6e89be6
1 parent ad433a5
commit 6e89be6
Showing 1 changed file with 28 additions and 41 deletions.
diff --git a/imgui_draw.cpp b/imgui_draw.cpp
@@ -813,30 +813,34 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun
         const int vtx_count = (points_count*2);
         PrimReserve(idx_count, vtx_count);
 
-        const ImDrawIdx common_idx = (ImDrawIdx)_VtxCurrentIdx;
+        // Add indexes for fill
+        unsigned int vtx_inner_idx = _VtxCurrentIdx;
+        unsigned int vtx_outer_idx = _VtxCurrentIdx + 1;
+        for (int i = 2; i < points_count; i++)
+        {
+            _IdxWritePtr[0] = (ImDrawIdx)(vtx_inner_idx); _IdxWritePtr[1] = (ImDrawIdx)(vtx_inner_idx + ((i - 1) << 1)); _IdxWritePtr[2] = (ImDrawIdx)(vtx_inner_idx + (i << 1));
+            _IdxWritePtr += 3;
+        }
 
-        for (int i0 = points_count-2, i1 = i0+1, i2 = 0; i2 < points_count; i0 = i1, i1=i2++)
+        // Compute normals
+        for (int i0 = points_count - 1, i1 = 0; i1 < points_count; i0 = i1++)
         {
             const ImVec2& p0 = points[i0];
             const ImVec2& p1 = points[i1];
-            const ImVec2& p2 = points[i2];
+            ImVec2 diff = p1 - p0;
+            diff *= ImInvLength(diff, 1.0f);
+            _VtxWritePtr[i0 << 1].pos.x = diff.y;
+            _VtxWritePtr[i0 << 1].pos.y = -diff.x;
+        }
 
-            ImVec2 n0 = p1 - p0;
-            ImVec2 n1 = p2 - p1;
-            {
-                float n0l = ImInvLength(n0, 1);
-                float n1l = ImInvLength(n1, 1);
-                float temp0 = n0.x;
-                n0.x = n0.y;
-                n0.y = -temp0;
-                float temp1 = n1.x;
-                n1.x = n1.y;
-                n1.y = -temp1;
-                n0 *= n0l;
-                n1 *= n1l;
-            }
+        ImVec2 n0 = _VtxWritePtr[(points_count-1) << 1].pos;
 
+        for (int i0 = points_count - 1, i1 = 0; i1 < points_count; i0 = i1++)
+        {
+            // Average normals
+            const ImVec2& n1 = _VtxWritePtr[0].pos;
             ImVec2 dm = (n0 + n1) * 0.5f;
+            n0 = n1;
             float dmr2 = dm.x*dm.x + dm.y*dm.y;
             if (dmr2 > 0.000001f)
             {
@@ -846,34 +850,17 @@ void ImDrawList::AddConvexPolyFilled(const ImVec2* points, const int points_coun
             }
             dm *= AA_SIZE * 0.5f;
 
-            // 2 vertices
-            _VtxWritePtr[0].pos = p1 - dm; _VtxWritePtr[0].uv = uv; _VtxWritePtr[0].col = col;          // Inner
-            _VtxWritePtr[1].pos = p1 + dm; _VtxWritePtr[1].uv = uv; _VtxWritePtr[1].col = col_trans;    // Outer
+            // Add vertices
+            _VtxWritePtr[0].pos = (points[i1] - dm); _VtxWritePtr[0].uv = uv; _VtxWritePtr[0].col = col;        // Inner
+            _VtxWritePtr[1].pos = (points[i1] + dm); _VtxWritePtr[1].uv = uv; _VtxWritePtr[1].col = col_trans;  // Outer
             _VtxWritePtr += 2;
 
-            // 2 triangles for border
-            // Order:
-            // [0] +0 [1] +1 [2] +2
-            // [3] +1 [4] +2 [5] +3
-            _IdxWritePtr[0] = (ImDrawIdx)(_VtxCurrentIdx + 0); _IdxWritePtr[1] = (ImDrawIdx)(_VtxCurrentIdx + 1); _IdxWritePtr[2] = (ImDrawIdx)(_VtxCurrentIdx + 2);
-            _IdxWritePtr[3] = (ImDrawIdx)(_VtxCurrentIdx + 1); _IdxWritePtr[4] = (ImDrawIdx)(_VtxCurrentIdx + 2); _IdxWritePtr[5] = (ImDrawIdx)(_VtxCurrentIdx + 3);
+            // Add indexes for fringes
+            _IdxWritePtr[0] = (ImDrawIdx)(vtx_inner_idx + (i1 << 1)); _IdxWritePtr[1] = (ImDrawIdx)(vtx_inner_idx + (i0 << 1)); _IdxWritePtr[2] = (ImDrawIdx)(vtx_outer_idx + (i0 << 1));
+            _IdxWritePtr[3] = (ImDrawIdx)(vtx_outer_idx + (i0 << 1)); _IdxWritePtr[4] = (ImDrawIdx)(vtx_outer_idx + (i1 << 1)); _IdxWritePtr[5] = (ImDrawIdx)(vtx_inner_idx + (i1 << 1));
             _IdxWritePtr += 6;
-
-            // Maybe 1 triangle for fill
-            if (i2 >= 2) 
-            {
-                _IdxWritePtr[0] = common_idx; _IdxWritePtr[1] = (ImDrawIdx)(_VtxCurrentIdx-2); _IdxWritePtr[2] = (ImDrawIdx)(_VtxCurrentIdx);
-                _IdxWritePtr += 3;
-            }
-
-            _VtxCurrentIdx += 2;
         }
-
-        // Patch last indices to point to 1st iteration vertices
-        int offset = points_count < 3 ? 6 : 9; // If there is a fill triangle at the end of the buffer
-        _IdxWritePtr[2-offset] = common_idx;
-        _IdxWritePtr[4-offset] = common_idx;
-        _IdxWritePtr[5-offset] = common_idx + 1;
+        _VtxCurrentIdx += (ImDrawIdx)vtx_count;
     }
     else
     {