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https://github.com/libretro/dolphin
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76 lines
2.4 KiB
C++
76 lines
2.4 KiB
C++
// Copyright 2009 Dolphin Emulator Project
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// Licensed under GPLv2+
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// Refer to the license.txt file included.
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#include "VideoCommon/BPMemory.h"
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#include "Common/BitUtils.h"
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// BP state
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// STATE_TO_SAVE
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BPMemory bpmem;
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bool BlendMode::UseLogicOp() const
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{
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// Logicop bit has lowest priority.
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if (subtract || blendenable || !logicopenable)
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return false;
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// Fast path for Kirby's Return to Dreamland, they use it with dstAlpha.
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if (logicmode == BlendMode::NOOP)
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return false;
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return true;
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}
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bool FogParams::IsNaNCase() const
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{
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// Check for the case where both a and c are infinity or NaN.
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// On hardware, this results in the following colors:
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//
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// -------------------------------------------------------
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// | A | C | Result | A | C | Result |
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// -------------------------------------------------------
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// | inf | inf | Fogged | inf | nan | Fogged |
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// | inf | -inf | Unfogged | inf | -nan | Unfogged |
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// | -inf | inf | Unfogged | -inf | nan | Unfogged |
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// | -inf | -inf | Unfogged | -inf | -nan | Unfogged |
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// -------------------------------------------------------
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// | nan | inf | Fogged | nan | nan | Fogged |
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// | nan | -inf | Unfogged | nan | -nan | Unfogged |
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// | -nan | inf | Unfogged | -nan | nan | Unfogged |
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// | -nan | -inf | Unfogged | -nan | -nan | Unfogged |
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// -------------------------------------------------------
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//
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// We replicate this by returning A=0, and C=inf for the inf/inf case, otherwise -inf.
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// This ensures we do not pass a NaN to the GPU, and -inf/inf clamp to 0/1 respectively.
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return a.exp == 255 && c_proj_fsel.c_exp == 255;
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}
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float FogParams::GetA() const
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{
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if (IsNaNCase())
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return 0.0f;
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// scale mantissa from 11 to 23 bits
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const u32 integral = (static_cast<u32>(a.sign) << 31) | (static_cast<u32>(a.exp) << 23) |
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(static_cast<u32>(a.mant) << 12);
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return Common::BitCast<float>(integral);
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}
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float FogParams::GetC() const
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{
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if (IsNaNCase())
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{
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constexpr float inf = std::numeric_limits<float>::infinity();
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return !a.sign && !c_proj_fsel.c_sign ? -inf : inf;
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}
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// scale mantissa from 11 to 23 bits
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const u32 integral = (c_proj_fsel.c_sign.Value() << 31) | (c_proj_fsel.c_exp.Value() << 23) |
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(c_proj_fsel.c_mant.Value() << 12);
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return Common::BitCast<float>(integral);
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}
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