Import thekla_atlas

As requested by reduz, an import of thekla_atlas into thirdparty/

1 files changed, 159 insertions, 0 deletions

diff --git a/thirdparty/thekla_atlas/nvmesh/raster/ClippedTriangle.h b/thirdparty/thekla_atlas/nvmesh/raster/ClippedTriangle.h
new file mode 100644
index 0000000000..0947d4851c
--- /dev/null
+++ b/thirdparty/thekla_atlas/nvmesh/raster/ClippedTriangle.h
@@ -0,0 +1,159 @@
+// Copyright NVIDIA Corporation 2007 -- Denis Kovacs <den.kovacs@gmail.com>
+
+#pragma once
+#ifndef NV_MESH_CLIPPEDTRIANGLE_H
+#define NV_MESH_CLIPPEDTRIANGLE_H
+
+#include <nvmath/Vector.h>
+
+namespace nv
+{
+
+    class ClippedTriangle
+    {
+    public:
+        ClippedTriangle(Vector2::Arg a, Vector2::Arg b, Vector2::Arg c) 
+        {
+            m_numVertices = 3;
+            m_activeVertexBuffer = 0;
+
+            m_verticesA[0]=a;
+            m_verticesA[1]=b;
+            m_verticesA[2]=c;
+
+            m_vertexBuffers[0] = m_verticesA;
+            m_vertexBuffers[1] = m_verticesB;
+        }
+
+        uint vertexCount()
+        {
+            return m_numVertices;
+        }
+
+        const Vector2 * vertices()
+        {
+            return m_vertexBuffers[m_activeVertexBuffer];
+        }
+
+        inline void clipHorizontalPlane(float offset, float clipdirection) 
+        {
+            Vector2 * v  = m_vertexBuffers[m_activeVertexBuffer];
+            m_activeVertexBuffer ^= 1;
+            Vector2 * v2 = m_vertexBuffers[m_activeVertexBuffer];
+
+            v[m_numVertices] = v[0];
+
+            float dy2,   dy1 = offset - v[0].y;
+            int   dy2in, dy1in = clipdirection*dy1 >= 0;
+            uint  p=0;
+
+            for (uint k=0; k<m_numVertices; k++)
+            {
+                dy2   = offset - v[k+1].y;
+                dy2in = clipdirection*dy2 >= 0;
+
+                if (dy1in) v2[p++] = v[k];
+
+                if ( dy1in + dy2in == 1 ) // not both in/out
+                {
+                    float dx = v[k+1].x - v[k].x;
+                    float dy = v[k+1].y - v[k].y;
+                    v2[p++] = Vector2(v[k].x + dy1*(dx/dy), offset);
+                }
+
+                dy1 = dy2; dy1in = dy2in;
+            }
+            m_numVertices = p;
+
+            //for (uint k=0; k<m_numVertices; k++) printf("(%f, %f)\n", v2[k].x, v2[k].y); printf("\n");
+        }
+
+        inline void clipVerticalPlane(float offset, float clipdirection ) 
+        {
+            Vector2 * v  = m_vertexBuffers[m_activeVertexBuffer];
+            m_activeVertexBuffer ^= 1;
+            Vector2 * v2 = m_vertexBuffers[m_activeVertexBuffer];
+
+            v[m_numVertices] = v[0];
+
+            float dx2,   dx1   = offset - v[0].x;
+            int   dx2in, dx1in = clipdirection*dx1 >= 0;
+            uint  p=0;
+
+            for (uint k=0; k<m_numVertices; k++)
+            {
+                dx2 = offset - v[k+1].x;
+                dx2in = clipdirection*dx2 >= 0;
+
+                if (dx1in) v2[p++] = v[k];
+
+                if ( dx1in + dx2in == 1 ) // not both in/out
+                {
+                    float dx = v[k+1].x - v[k].x;
+                    float dy = v[k+1].y - v[k].y;
+                    v2[p++] = Vector2(offset, v[k].y + dx1*(dy/dx));
+                }
+
+                dx1 = dx2; dx1in = dx2in;
+            }
+            m_numVertices = p;
+
+            //for (uint k=0; k<m_numVertices; k++) printf("(%f, %f)\n", v2[k].x, v2[k].y); printf("\n");
+        }
+
+        void computeAreaCentroid()
+        {
+            Vector2 * v  = m_vertexBuffers[m_activeVertexBuffer];
+            v[m_numVertices] = v[0];
+
+            m_area = 0;
+            float centroidx=0, centroidy=0;
+            for (uint k=0; k<m_numVertices; k++)
+            {
+                // http://local.wasp.uwa.edu.au/~pbourke/geometry/polyarea/
+                float f = v[k].x*v[k+1].y - v[k+1].x*v[k].y;
+                m_area += f;
+                centroidx += f * (v[k].x + v[k+1].x);
+                centroidy += f * (v[k].y + v[k+1].y);
+            }
+            m_area = 0.5f * fabs(m_area);
+            if (m_area==0) {
+                m_centroid = Vector2(0.0f);
+            } else {
+                m_centroid = Vector2(centroidx/(6*m_area), centroidy/(6*m_area));
+            }
+        }
+
+        void clipAABox(float x0, float y0, float x1, float y1)
+        {
+            clipVerticalPlane  ( x0, -1);
+            clipHorizontalPlane( y0, -1);
+            clipVerticalPlane  ( x1,  1);
+            clipHorizontalPlane( y1,  1);
+
+            computeAreaCentroid();
+        }
+
+        Vector2 centroid()
+        {
+            return m_centroid;
+        }
+
+        float area()
+        {
+            return m_area;
+        }
+
+    private:
+        Vector2 m_verticesA[7+1];
+        Vector2 m_verticesB[7+1];
+        Vector2 * m_vertexBuffers[2];
+        uint    m_numVertices;
+        uint    m_activeVertexBuffer;
+        float   m_area;
+        Vector2 m_centroid;
+    };
+
+} // nv namespace
+
+#endif // NV_MESH_CLIPPEDTRIANGLE_H