dolphin/Source/Core/VideoBackends/Software/TextureSampler.cpp

// Copyright 2009 Dolphin Emulator Project
// Licensed under GPLv2+
// Refer to the license.txt file included.

#include <algorithm>
#include <cmath>

#include "Common/Common.h"
#include "Core/HW/Memmap.h"
#include "VideoBackends/Software/TextureSampler.h"

#include "VideoCommon/BPMemory.h"
#include "VideoCommon/SamplerCommon.h"
#include "VideoCommon/TextureDecoder.h"

#define ALLOW_MIPMAP 1

namespace TextureSampler
{
static inline void WrapCoord(int* coordp, int wrapMode, int imageSize)
{
  int coord = *coordp;
  switch (wrapMode)
  {
  case 0:  // clamp
    coord = (coord > imageSize) ? imageSize : (coord < 0) ? 0 : coord;
    break;
  case 1:  // wrap
    coord = coord % (imageSize + 1);
    coord = (coord < 0) ? imageSize + coord : coord;
    break;
  case 2:  // mirror
  {
    int sizePlus1 = imageSize + 1;
    int div = coord / sizePlus1;
    coord = coord - (div * sizePlus1);
    coord = (coord < 0) ? -coord : coord;
    coord = (div & 1) ? imageSize - coord : coord;
  }
  break;
  }
  *coordp = coord;
}

static inline void SetTexel(u8* inTexel, u32* outTexel, u32 fract)
{
  outTexel[0] = inTexel[0] * fract;
  outTexel[1] = inTexel[1] * fract;
  outTexel[2] = inTexel[2] * fract;
  outTexel[3] = inTexel[3] * fract;
}

static inline void AddTexel(u8* inTexel, u32* outTexel, u32 fract)
{
  outTexel[0] += inTexel[0] * fract;
  outTexel[1] += inTexel[1] * fract;
  outTexel[2] += inTexel[2] * fract;
  outTexel[3] += inTexel[3] * fract;
}

void Sample(s32 s, s32 t, s32 lod, bool linear, u8 texmap, u8* sample)
{
  int baseMip = 0;
  bool mipLinear = false;

#if (ALLOW_MIPMAP)
  FourTexUnits& texUnit = bpmem.tex[(texmap >> 2) & 1];
  TexMode0& tm0 = texUnit.texMode0[texmap & 3];

  s32 lodFract = lod & 0xf;

  if (lod > 0 && SamplerCommon::AreBpTexMode0MipmapsEnabled(tm0))
  {
    // use mipmap
    baseMip = lod >> 4;
    mipLinear = (lodFract && tm0.min_filter & TexMode0::TEXF_LINEAR);

    // if using nearest mip filter and lodFract >= 0.5 round up to next mip
    baseMip += (lodFract >> 3) & (tm0.min_filter & TexMode0::TEXF_POINT);
  }

  if (mipLinear)
  {
    u8 sampledTex[4];
    u32 texel[4];

    SampleMip(s, t, baseMip, linear, texmap, sampledTex);
    SetTexel(sampledTex, texel, (16 - lodFract));

    SampleMip(s, t, baseMip + 1, linear, texmap, sampledTex);
    AddTexel(sampledTex, texel, lodFract);

    sample[0] = (u8)(texel[0] >> 4);
    sample[1] = (u8)(texel[1] >> 4);
    sample[2] = (u8)(texel[2] >> 4);
    sample[3] = (u8)(texel[3] >> 4);
  }
  else
#endif
  {
    SampleMip(s, t, baseMip, linear, texmap, sample);
  }
}

void SampleMip(s32 s, s32 t, s32 mip, bool linear, u8 texmap, u8* sample)
{
  FourTexUnits& texUnit = bpmem.tex[(texmap >> 2) & 1];
  u8 subTexmap = texmap & 3;

  TexMode0& tm0 = texUnit.texMode0[subTexmap];
  TexImage0& ti0 = texUnit.texImage0[subTexmap];
  TexTLUT& texTlut = texUnit.texTlut[subTexmap];
  TlutFormat tlutfmt = (TlutFormat)texTlut.tlut_format;

  u8 *imageSrc, *imageSrcOdd = nullptr;
  if (texUnit.texImage1[subTexmap].image_type)
  {
    imageSrc = &texMem[texUnit.texImage1[subTexmap].tmem_even * TMEM_LINE_SIZE];
    if (ti0.format == GX_TF_RGBA8)
      imageSrcOdd = &texMem[texUnit.texImage2[subTexmap].tmem_odd * TMEM_LINE_SIZE];
  }
  else
  {
    u32 imageBase = texUnit.texImage3[subTexmap].image_base << 5;
    imageSrc = Memory::GetPointer(imageBase);
  }

  int imageWidth = ti0.width;
  int imageHeight = ti0.height;

  int tlutAddress = texTlut.tmem_offset << 9;
  const u8* tlut = &texMem[tlutAddress];

  // reduce sample location and texture size to mip level
  // move texture pointer to mip location
  if (mip)
  {
    int mipWidth = imageWidth + 1;
    int mipHeight = imageHeight + 1;

    int fmtWidth = TexDecoder_GetBlockWidthInTexels(ti0.format);
    int fmtHeight = TexDecoder_GetBlockHeightInTexels(ti0.format);
    int fmtDepth = TexDecoder_GetTexelSizeInNibbles(ti0.format);

    imageWidth >>= mip;
    imageHeight >>= mip;
    s >>= mip;
    t >>= mip;

    while (mip)
    {
      mipWidth = std::max(mipWidth, fmtWidth);
      mipHeight = std::max(mipHeight, fmtHeight);
      u32 size = (mipWidth * mipHeight * fmtDepth) >> 1;

      imageSrc += size;
      mipWidth >>= 1;
      mipHeight >>= 1;
      mip--;
    }
  }

  if (linear)
  {
    // offset linear sampling
    s -= 64;
    t -= 64;

    // integer part of sample location
    int imageS = s >> 7;
    int imageT = t >> 7;

    // linear sampling
    int imageSPlus1 = imageS + 1;
    int fractS = s & 0x7f;

    int imageTPlus1 = imageT + 1;
    int fractT = t & 0x7f;

    u8 sampledTex[4];
    u32 texel[4];

    WrapCoord(&imageS, tm0.wrap_s, imageWidth);
    WrapCoord(&imageT, tm0.wrap_t, imageHeight);
    WrapCoord(&imageSPlus1, tm0.wrap_s, imageWidth);
    WrapCoord(&imageTPlus1, tm0.wrap_t, imageHeight);

    if (!(ti0.format == GX_TF_RGBA8 && texUnit.texImage1[subTexmap].image_type))
    {
      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageT, imageWidth, ti0.format, tlut,
                             tlutfmt);
      SetTexel(sampledTex, texel, (128 - fractS) * (128 - fractT));

      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageT, imageWidth, ti0.format,
                             tlut, tlutfmt);
      AddTexel(sampledTex, texel, (fractS) * (128 - fractT));

      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageS, imageTPlus1, imageWidth, ti0.format,
                             tlut, tlutfmt);
      AddTexel(sampledTex, texel, (128 - fractS) * (fractT));

      TexDecoder_DecodeTexel(sampledTex, imageSrc, imageSPlus1, imageTPlus1, imageWidth, ti0.format,
                             tlut, tlutfmt);
      AddTexel(sampledTex, texel, (fractS) * (fractT));
    }
    else
    {
      TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageS, imageT,
                                          imageWidth);
      SetTexel(sampledTex, texel, (128 - fractS) * (128 - fractT));

      TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageSPlus1, imageT,
                                          imageWidth);
      AddTexel(sampledTex, texel, (fractS) * (128 - fractT));

      TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageS, imageTPlus1,
                                          imageWidth);
      AddTexel(sampledTex, texel, (128 - fractS) * (fractT));

      TexDecoder_DecodeTexelRGBA8FromTmem(sampledTex, imageSrc, imageSrcOdd, imageSPlus1,
                                          imageTPlus1, imageWidth);
      AddTexel(sampledTex, texel, (fractS) * (fractT));
    }

    sample[0] = (u8)(texel[0] >> 14);
    sample[1] = (u8)(texel[1] >> 14);
    sample[2] = (u8)(texel[2] >> 14);
    sample[3] = (u8)(texel[3] >> 14);
  }
  else
  {
    // integer part of sample location
    int imageS = s >> 7;
    int imageT = t >> 7;

    // nearest neighbor sampling
    WrapCoord(&imageS, tm0.wrap_s, imageWidth);
    WrapCoord(&imageT, tm0.wrap_t, imageHeight);

    if (!(ti0.format == GX_TF_RGBA8 && texUnit.texImage1[subTexmap].image_type))
      TexDecoder_DecodeTexel(sample, imageSrc, imageS, imageT, imageWidth, ti0.format, tlut,
                             tlutfmt);
    else
      TexDecoder_DecodeTexelRGBA8FromTmem(sample, imageSrc, imageSrcOdd, imageS, imageT,
                                          imageWidth);
  }
}
}