Ticket #472: 472.patch

source/graphics/Terrain.cpp

@@ -340 +340 @@
            + zf  * ((1 - xf) * h01 + xf * h11)));
 }
 
+CFixed_23_8 CTerrain::GetExactGroundLevelFixed(CFixed_23_8 x, CFixed_23_8 z) const
+{
+    // Clamp to size-2 so we can use the tiles (xi,zi)-(xi+1,zi+1)
+    const ssize_t xi = clamp((ssize_t)(x/CELL_SIZE).ToInt_RoundToZero(), (ssize_t)0, m_MapSize-2);
+    const ssize_t zi = clamp((ssize_t)(z/CELL_SIZE).ToInt_RoundToZero(), (ssize_t)0, m_MapSize-2);
+
+    const CFixed_23_8 xf = clamp((x/CELL_SIZE)-CFixed_23_8::FromInt(xi), CFixed_23_8::FromInt(0), CFixed_23_8::FromInt(1));
+    const CFixed_23_8 zf = clamp((z/CELL_SIZE)-CFixed_23_8::FromInt(zi), CFixed_23_8::FromInt(0), CFixed_23_8::FromInt(1));
+
+    u16 h00 = m_Heightmap[zi*m_MapSize + xi];
+    u16 h01 = m_Heightmap[(zi+1)*m_MapSize + xi];
+    u16 h10 = m_Heightmap[zi*m_MapSize + (xi+1)];
+    u16 h11 = m_Heightmap[(zi+1)*m_MapSize + (xi+1)];
+    // Linearly interpolate
+    return (((CFixed_23_8::FromInt(1) - zf).Multiply((CFixed_23_8::FromInt(1) - xf) * h00 + xf * h10)
+               + zf.Multiply((CFixed_23_8::FromInt(1) - xf) * h01 + xf * h11))/HEIGHT_UNITS_PER_METRE);
+}
+
 ///////////////////////////////////////////////////////////////////////////////
 // Resize: resize this terrain to the given size (in patches per side)
 void CTerrain::Resize(ssize_t size)

source/graphics/Terrain.h

@@ -23 +23 @@
 #define INCLUDED_TERRAIN
 
 #include "maths/Vector3D.h"
+#include "maths/Fixed.h"
 #include "graphics/SColor.h"
 #include "lib/sysdep/cpu.h"
 
@@ -80 +81 @@
 
     float GetVertexGroundLevel(ssize_t i, ssize_t j) const;
     float GetExactGroundLevel(float x, float z) const;
+    CFixed_23_8 GetExactGroundLevelFixed(CFixed_23_8 x, CFixed_23_8 z) const;
     float GetExactGroundLevel(const CVector2D& v) const;
 
     float GetSlope(float x, float z) const ;

source/simulation2/components/CCmpTerrain.cpp

@@ -60 +60 @@
 
     virtual entity_pos_t GetGroundLevel(entity_pos_t x, entity_pos_t z)
     {
-        float height = m_Terrain->GetExactGroundLevel(x.ToFloat(), z.ToFloat());
-        // TODO: get rid of floats
-
-        return entity_pos_t::FromFloat(height);
+        return m_Terrain->GetExactGroundLevelFixed(x, z);
     }
 
     virtual float GetGroundLevel(float x, float z)