text: // Copyright (C) 2002-2012 Nikolaus Gebhardt / Thomas Alten
  // This file is part of the "Irrlicht Engine".
  // For conditions of distribution and use, see copyright notice in irrlicht.h
  
  #include "IrrCompileConfig.h"
  #include "IBurningShader.h"
  
  #ifdef _IRR_COMPILE_WITH_BURNINGSVIDEO_
  
  // compile flag for this file
  #undef USE_ZBUFFER
  #undef IPOL_Z
  #undef CMP_Z
  #undef WRITE_Z
  
  #undef IPOL_W
  #undef CMP_W
  #undef WRITE_W
  
  #undef SUBTEXEL
  #undef INVERSE_W
  
  #undef IPOL_C0
  #undef IPOL_T0
  #undef IPOL_T1
  
  // define render case
  #define SUBTEXEL
  #define INVERSE_W
  
  #define USE_ZBUFFER
  #define IPOL_W
  #define CMP_W
  #define WRITE_W
  
  #define IPOL_C0
  #define IPOL_T0
  //#define IPOL_T1
  
  // apply global override
  #ifndef SOFTWARE_DRIVER_2_PERSPECTIVE_CORRECT
      #undef INVERSE_W
  #endif
  
  #ifndef SOFTWARE_DRIVER_2_SUBTEXEL
      #undef SUBTEXEL
  #endif
  
  #ifndef SOFTWARE_DRIVER_2_USE_VERTEX_COLOR
      #undef IPOL_C0
  #endif
  
  #if !defined ( SOFTWARE_DRIVER_2_USE_WBUFFER ) && defined ( USE_ZBUFFER )
      #ifndef SOFTWARE_DRIVER_2_PERSPECTIVE_CORRECT
          #undef IPOL_W
      #endif
      #define IPOL_Z
  
      #ifdef CMP_W
          #undef CMP_W
          #define CMP_Z
      #endif
  
      #ifdef WRITE_W
          #undef WRITE_W
          #define WRITE_Z
      #endif
  
  #endif
  
  
  namespace irr
  {
  
  namespace video
  {
  
  class CTRTextureGouraud2 : public IBurningShader
  {
  public:
  
      //! constructor
      CTRTextureGouraud2(CBurningVideoDriver* driver);
  
      //! draws an indexed triangle list
      virtual void drawTriangle ( const s4DVertex *a,const s4DVertex *b,const s4DVertex *c );
  
  
  private:
      void scanline_bilinear ();
      sScanConvertData scan;
      sScanLineData line;
  
  };
  
  //! constructor
  CTRTextureGouraud2::CTRTextureGouraud2(CBurningVideoDriver* driver)
  : IBurningShader(driver)
  {
      #ifdef _DEBUG
      setDebugName("CTRTextureGouraud2");
      #endif
  }
  
  
  
  /*!
  */
  void CTRTextureGouraud2::scanline_bilinear ()
  {
      tVideoSample *dst;
  
  #ifdef USE_ZBUFFER
      fp24 *z;
  #endif
  
      s32 xStart;
      s32 xEnd;
      s32 dx;
  
  
  #ifdef SUBTEXEL
      f32 subPixel;
  #endif
  
  #ifdef IPOL_Z
      f32 slopeZ;
  #endif
  #ifdef IPOL_W
      fp24 slopeW;
  #endif
  #ifdef IPOL_C0
      sVec4 slopeC;
  #endif
  #ifdef IPOL_T0
      sVec2 slopeT[BURNING_MATERIAL_MAX_TEXTURES];
  #endif
  
      // apply top-left fill-convention, left
      xStart = core::ceil32( line.x[0] );
      xEnd = core::ceil32( line.x[1] ) - 1;
  
      dx = xEnd - xStart;
  
      if ( dx < 0 )
          return;
  
      // slopes
      const f32 invDeltaX = core::reciprocal_approxim ( line.x[1] - line.x[0] );
  
  #ifdef IPOL_Z
      slopeZ = (line.z[1] - line.z[0]) * invDeltaX;
  #endif
  #ifdef IPOL_W
      slopeW = (line.w[1] - line.w[0]) * invDeltaX;
  #endif
  #ifdef IPOL_C0
      slopeC = (line.c[0][1] - line.c[0][0]) * invDeltaX;
  #endif
  #ifdef IPOL_T0
      slopeT[0] = (line.t[0][1] - line.t[0][0]) * invDeltaX;
  #endif
  #ifdef IPOL_T1
      slopeT[1] = (line.t[1][1] - line.t[1][0]) * invDeltaX;
  #endif
  
  #ifdef SUBTEXEL
      subPixel = ( (f32) xStart ) - line.x[0];
  #ifdef IPOL_Z
      line.z[0] += slopeZ * subPixel;
  #endif
  #ifdef IPOL_W
      line.w[0] += slopeW * subPixel;
  #endif
  #ifdef IPOL_C0
      line.c[0][0] += slopeC * subPixel;
  #endif
  #ifdef IPOL_T0
      line.t[0][0] += slopeT[0] * subPixel;
  #endif
  #ifdef IPOL_T1
      line.t[1][0] += slopeT[1] * subPixel;
  #endif
  #endif
  
      dst = (tVideoSample*)RenderTarget->lock() + ( line.y * RenderTarget->getDimension().Width ) + xStart;
  
  #ifdef USE_ZBUFFER
      z = (fp24*) DepthBuffer->lock() + ( line.y * RenderTarget->getDimension().Width ) + xStart;
  #endif
  
  
  #ifdef INVERSE_W
      f32 inversew;
  #endif
  
      tFixPoint tx0;
      tFixPoint ty0;
  
      tFixPoint r0, g0, b0;
  
  #ifdef IPOL_C0
      tFixPoint r1, g1, b1;
  #endif
  
  #ifdef BURNINGVIDEO_RENDERER_FAST
      u32 dIndex = ( line.y & 3 ) << 2;
  #endif
  
      for ( s32 i = 0; i <= dx; ++i )
      {
  #ifdef CMP_Z
          if ( line.z[0] < z[i] )
  #endif
  #ifdef CMP_W
          if ( line.w[0] >= z[i] )
  #endif
          {
  #ifdef WRITE_Z
              z[i] = line.z[0];
  #endif
  #ifdef WRITE_W
              z[i] = line.w[0];
  #endif
  
  
  #ifdef INVERSE_W
              inversew = fix_inverse32 ( line.w[0] );
              tx0 = tofix ( line.t[0][0].x, inversew);
              ty0 = tofix ( line.t[0][0].y, inversew);
  
  #ifdef IPOL_C0
              r1 = tofix ( line.c[0][0].y ,inversew );
              g1 = tofix ( line.c[0][0].z ,inversew );
              b1 = tofix ( line.c[0][0].w ,inversew );
  #endif
  
  #else
              tx0 = tofix ( line.t[0][0].x );
              ty0 = tofix ( line.t[0][0].y );
  #ifdef IPOL_C0
              getTexel_plain2 ( r1, g1, b1, line.c[0][0] );
  #endif
  #endif
  
  #ifdef IPOL_C0
              getSample_texture ( r0, g0, b0, &IT[0], tx0,ty0 );
  
              dst[i] = fix_to_color ( imulFix ( r0, r1 ),
                                      imulFix ( g0, g1 ),
                                      imulFix ( b0, b1 )
                                  );
  #else
  
  #ifdef BURNINGVIDEO_RENDERER_FAST
              const tFixPointu d = dithermask [ dIndex | ( i ) & 3 ];
              dst[i] = getTexel_plain ( &IT[0], d + tx0, d + ty0 );
  #else
              getSample_texture ( r0, g0, b0, &IT[0], tx0,ty0 );
              dst[i] = fix_to_color ( r0, g0, b0 );
  #endif
  
  #endif
  
          }
  
  #ifdef IPOL_Z
          line.z[0] += slopeZ;
  #endif
  #ifdef IPOL_W
          line.w[0] += slopeW;
  #endif
  #ifdef IPOL_C0
          line.c[0][0] += slopeC;
  #endif
  #ifdef IPOL_T0
          line.t[0][0] += slopeT[0];
  #endif
  #ifdef IPOL_T1
          line.t[1][0] += slopeT[1];
  #endif
      }
  
  }
  
  void CTRTextureGouraud2::drawTriangle ( const s4DVertex *a,const s4DVertex *b,const s4DVertex *c )
  {
      // sort on height, y
      if ( F32_A_GREATER_B ( a->Pos.y , b->Pos.y ) ) swapVertexPointer(&a, &b);
      if ( F32_A_GREATER_B ( b->Pos.y , c->Pos.y ) ) swapVertexPointer(&b, &c);
      if ( F32_A_GREATER_B ( a->Pos.y , b->Pos.y ) ) swapVertexPointer(&a, &b);
  
      const f32 ca = c->Pos.y - a->Pos.y;
      const f32 ba = b->Pos.y - a->Pos.y;
      const f32 cb = c->Pos.y - b->Pos.y;
      // calculate delta y of the edges
      scan.invDeltaY[0] = core::reciprocal( ca );
      scan.invDeltaY[1] = core::reciprocal( ba );
      scan.invDeltaY[2] = core::reciprocal( cb );
  
      if ( F32_LOWER_EQUAL_0 ( scan.invDeltaY[0] ) )
          return;
  
      // find if the major edge is left or right aligned
      f32 temp[4];
  
      temp[0] = a->Pos.x - c->Pos.x;
      temp[1] = -ca;
      temp[2] = b->Pos.x - a->Pos.x;
      temp[3] = ba;
  
      scan.left = ( temp[0] * temp[3] - temp[1] * temp[2] ) > 0.f ? 0 : 1;
      scan.right = 1 - scan.left;
  
      // calculate slopes for the major edge
      scan.slopeX[0] = (c->Pos.x - a->Pos.x) * scan.invDeltaY[0];
      scan.x[0] = a->Pos.x;
  
  #ifdef IPOL_Z
      scan.slopeZ[0] = (c->Pos.z - a->Pos.z) * scan.invDeltaY[0];
      scan.z[0] = a->Pos.z;
  #endif
  
  #ifdef IPOL_W
      scan.slopeW[0] = (c->Pos.w - a->Pos.w) * scan.invDeltaY[0];
      scan.w[0] = a->Pos.w;
  #endif
  
  #ifdef IPOL_C0
      scan.slopeC[0][0] = (c->Color[0] - a->Color[0]) * scan.invDeltaY[0];
      scan.c[0][0] = a->Color[0];
  #endif
  
  #ifdef IPOL_T0
      scan.slopeT[0][0] = (c->Tex[0] - a->Tex[0]) * scan.invDeltaY[0];
      scan.t[0][0] = a->Tex[0];
  #endif
  
  #ifdef IPOL_T1
      scan.slopeT[1][0] = (c->Tex[1] - a->Tex[1]) * scan.invDeltaY[0];
      scan.t[1][0] = a->Tex[1];
  #endif
  
      // top left fill convention y run
      s32 yStart;
      s32 yEnd;
  
  #ifdef SUBTEXEL
      f32 subPixel;
  #endif
  
      // rasterize upper sub-triangle
      if ( (f32) 0.0 != scan.invDeltaY[1]  )
      {
          // calculate slopes for top edge
          scan.slopeX[1] = (b->Pos.x - a->Pos.x) * scan.invDeltaY[1];
          scan.x[1] = a->Pos.x;
  
  #ifdef IPOL_Z
          scan.slopeZ[1] = (b->Pos.z - a->Pos.z) * scan.invDeltaY[1];
          scan.z[1] = a->Pos.z;
  #endif
  
  #ifdef IPOL_W
          scan.slopeW[1] = (b->Pos.w - a->Pos.w) * scan.invDeltaY[1];
          scan.w[1] = a->Pos.w;
  #endif
  
  #ifdef IPOL_C0
          scan.slopeC[0][1] = (b->Color[0] - a->Color[0]) * scan.invDeltaY[1];
          scan.c[0][1] = a->Color[0];
  #endif
  
  #ifdef IPOL_T0
          scan.slopeT[0][1] = (b->Tex[0] - a->Tex[0]) * scan.invDeltaY[1];
          scan.t[0][1] = a->Tex[0];
  #endif
  
  #ifdef IPOL_T1
          scan.slopeT[1][1] = (b->Tex[1] - a->Tex[1]) * scan.invDeltaY[1];
          scan.t[1][1] = a->Tex[1];
  #endif
  
          // apply top-left fill convention, top part
          yStart = core::ceil32( a->Pos.y );
          yEnd = core::ceil32( b->Pos.y ) - 1;
  
  #ifdef SUBTEXEL
          subPixel = ( (f32) yStart ) - a->Pos.y;
  
          // correct to pixel center
          scan.x[0] += scan.slopeX[0] * subPixel;
          scan.x[1] += scan.slopeX[1] * subPixel;        
  
  #ifdef IPOL_Z
          scan.z[0] += scan.slopeZ[0] * subPixel;
          scan.z[1] += scan.slopeZ[1] * subPixel;        
  #endif
  
  #ifdef IPOL_W
          scan.w[0] += scan.slopeW[0] * subPixel;
          scan.w[1] += scan.slopeW[1] * subPixel;        
  #endif
  
  #ifdef IPOL_C0
          scan.c[0][0] += scan.slopeC[0][0] * subPixel;
          scan.c[0][1] += scan.slopeC[0][1] * subPixel;        
  #endif
  
  #ifdef IPOL_T0
          scan.t[0][0] += scan.slopeT[0][0] * subPixel;
          scan.t[0][1] += scan.slopeT[0][1] * subPixel;        
  #endif
  
  #ifdef IPOL_T1
          scan.t[1][0] += scan.slopeT[1][0] * subPixel;
          scan.t[1][1] += scan.slopeT[1][1] * subPixel;        
  #endif
  
  #endif
  
          // rasterize the edge scanlines
          for( line.y = yStart; line.y <= yEnd; ++line.y)
          {
              line.x[scan.left] = scan.x[0];
              line.x[scan.right] = scan.x[1];
  
  #ifdef IPOL_Z
              line.z[scan.left] = scan.z[0];
              line.z[scan.right] = scan.z[1];
  #endif
  
  #ifdef IPOL_W
              line.w[scan.left] = scan.w[0];
              line.w[scan.right] = scan.w[1];
  #endif
  
  #ifdef IPOL_C0
              line.c[0][scan.left] = scan.c[0][0];
              line.c[0][scan.right] = scan.c[0][1];
  #endif
  
  #ifdef IPOL_T0
              line.t[0][scan.left] = scan.t[0][0];
              line.t[0][scan.right] = scan.t[0][1];
  #endif
  
  #ifdef IPOL_T1
              line.t[1][scan.left] = scan.t[1][0];
              line.t[1][scan.right] = scan.t[1][1];
  #endif
  
              // render a scanline
              scanline_bilinear ();
  
              scan.x[0] += scan.slopeX[0];
              scan.x[1] += scan.slopeX[1];
  
  #ifdef IPOL_Z
              scan.z[0] += scan.slopeZ[0];
              scan.z[1] += scan.slopeZ[1];
  #endif
  
  #ifdef IPOL_W
              scan.w[0] += scan.slopeW[0];
              scan.w[1] += scan.slopeW[1];
  #endif
  
  #ifdef IPOL_C0
              scan.c[0][0] += scan.slopeC[0][0];
              scan.c[0][1] += scan.slopeC[0][1];
  #endif
  
  #ifdef IPOL_T0
              scan.t[0][0] += scan.slopeT[0][0];
              scan.t[0][1] += scan.slopeT[0][1];
  #endif
  
  #ifdef IPOL_T1
              scan.t[1][0] += scan.slopeT[1][0];
              scan.t[1][1] += scan.slopeT[1][1];
  #endif
  
          }
      }
  
      // rasterize lower sub-triangle
      if ( (f32) 0.0 != scan.invDeltaY[2] )
      {
          // advance to middle point
          if( (f32) 0.0 != scan.invDeltaY[1] )
          {
              temp[0] = b->Pos.y - a->Pos.y;    // dy
  
              scan.x[0] = a->Pos.x + scan.slopeX[0] * temp[0];
  #ifdef IPOL_Z
              scan.z[0] = a->Pos.z + scan.slopeZ[0] * temp[0];
  #endif
  #ifdef IPOL_W
              scan.w[0] = a->Pos.w + scan.slopeW[0] * temp[0];
  #endif
  #ifdef IPOL_C0
              scan.c[0][0] = a->Color[0] + scan.slopeC[0][0] * temp[0];
  #endif
  #ifdef IPOL_T0
              scan.t[0][0] = a->Tex[0] + scan.slopeT[0][0] * temp[0];
  #endif
  #ifdef IPOL_T1
              scan.t[1][0] = a->Tex[1] + scan.slopeT[1][0] * temp[0];
  #endif
  
          }
  
          // calculate slopes for bottom edge
          scan.slopeX[1] = (c->Pos.x - b->Pos.x) * scan.invDeltaY[2];
          scan.x[1] = b->Pos.x;
  
  #ifdef IPOL_Z
          scan.slopeZ[1] = (c->Pos.z - b->Pos.z) * scan.invDeltaY[2];
          scan.z[1] = b->Pos.z;
  #endif
  
  #ifdef IPOL_W
          scan.slopeW[1] = (c->Pos.w - b->Pos.w) * scan.invDeltaY[2];
          scan.w[1] = b->Pos.w;
  #endif
  
  #ifdef IPOL_C0
          scan.slopeC[0][1] = (c->Color[0] - b->Color[0]) * scan.invDeltaY[2];
          scan.c[0][1] = b->Color[0];
  #endif
  
  #ifdef IPOL_T0
          scan.slopeT[0][1] = (c->Tex[0] - b->Tex[0]) * scan.invDeltaY[2];
          scan.t[0][1] = b->Tex[0];
  #endif
  
  #ifdef IPOL_T1
          scan.slopeT[1][1] = (c->Tex[1] - b->Tex[1]) * scan.invDeltaY[2];
          scan.t[1][1] = b->Tex[1];
  #endif
  
          // apply top-left fill convention, top part
          yStart = core::ceil32( b->Pos.y );
          yEnd = core::ceil32( c->Pos.y ) - 1;
  
  #ifdef SUBTEXEL
  
          subPixel = ( (f32) yStart ) - b->Pos.y;
  
          // correct to pixel center
          scan.x[0] += scan.slopeX[0] * subPixel;
          scan.x[1] += scan.slopeX[1] * subPixel;        
  
  #ifdef IPOL_Z
          scan.z[0] += scan.slopeZ[0] * subPixel;
          scan.z[1] += scan.slopeZ[1] * subPixel;        
  #endif
  
  #ifdef IPOL_W
          scan.w[0] += scan.slopeW[0] * subPixel;
          scan.w[1] += scan.slopeW[1] * subPixel;        
  #endif
  
  #ifdef IPOL_C0
          scan.c[0][0] += scan.slopeC[0][0] * subPixel;
          scan.c[0][1] += scan.slopeC[0][1] * subPixel;        
  #endif
  
  #ifdef IPOL_T0
          scan.t[0][0] += scan.slopeT[0][0] * subPixel;
          scan.t[0][1] += scan.slopeT[0][1] * subPixel;        
  #endif
  
  #ifdef IPOL_T1
          scan.t[1][0] += scan.slopeT[1][0] * subPixel;
          scan.t[1][1] += scan.slopeT[1][1] * subPixel;        
  #endif
  
  #endif
  
          // rasterize the edge scanlines
          for( line.y = yStart; line.y <= yEnd; ++line.y)
          {
              line.x[scan.left] = scan.x[0];
              line.x[scan.right] = scan.x[1];
  
  #ifdef IPOL_Z
              line.z[scan.left] = scan.z[0];
              line.z[scan.right] = scan.z[1];
  #endif
  
  #ifdef IPOL_W
              line.w[scan.left] = scan.w[0];
              line.w[scan.right] = scan.w[1];
  #endif
  
  #ifdef IPOL_C0
              line.c[0][scan.left] = scan.c[0][0];
              line.c[0][scan.right] = scan.c[0][1];
  #endif
  
  #ifdef IPOL_T0
              line.t[0][scan.left] = scan.t[0][0];
              line.t[0][scan.right] = scan.t[0][1];
  #endif
  
  #ifdef IPOL_T1
              line.t[1][scan.left] = scan.t[1][0];
              line.t[1][scan.right] = scan.t[1][1];
  #endif
  
              // render a scanline
              scanline_bilinear ( );
  
              scan.x[0] += scan.slopeX[0];
              scan.x[1] += scan.slopeX[1];
  
  #ifdef IPOL_Z
              scan.z[0] += scan.slopeZ[0];
              scan.z[1] += scan.slopeZ[1];
  #endif
  
  #ifdef IPOL_W
              scan.w[0] += scan.slopeW[0];
              scan.w[1] += scan.slopeW[1];
  #endif
  
  #ifdef IPOL_C0
              scan.c[0][0] += scan.slopeC[0][0];
              scan.c[0][1] += scan.slopeC[0][1];
  #endif
  
  #ifdef IPOL_T0
              scan.t[0][0] += scan.slopeT[0][0];
              scan.t[0][1] += scan.slopeT[0][1];
  #endif
  
  #ifdef IPOL_T1
              scan.t[1][0] += scan.slopeT[1][0];
              scan.t[1][1] += scan.slopeT[1][1];
  #endif
  
          }
      }
  
  }
  
  } // end namespace video
  } // end namespace irr
  
  #endif // _IRR_COMPILE_WITH_BURNINGSVIDEO_
  
  namespace irr
  {
  namespace video
  {
  
  //! creates a flat triangle renderer
  IBurningShader* createTriangleRendererTextureGouraud2(CBurningVideoDriver* driver)
  {
      #ifdef _IRR_COMPILE_WITH_BURNINGSVIDEO_
      return new CTRTextureGouraud2(driver);
      #else
      return 0;
      #endif // _IRR_COMPILE_WITH_BURNINGSVIDEO_
  }
  
  
  } // end namespace video
  } // end namespace irr
  
  
  
  