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BCTools.cpp
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151 lines (133 loc) · 4.97 KB
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/*
* Copyright 2019-2025 Diligent Graphics LLC
*
* Licensed under the Apache License, Version 2.0 (the "License");
* you may not use this file except in compliance with the License.
* You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*
* In no event and under no legal theory, whether in tort (including negligence),
* contract, or otherwise, unless required by applicable law (such as deliberate
* and grossly negligent acts) or agreed to in writing, shall any Contributor be
* liable for any damages, including any direct, indirect, special, incidental,
* or consequential damages of any character arising as a result of this License or
* out of the use or inability to use the software (including but not limited to damages
* for loss of goodwill, work stoppage, computer failure or malfunction, or any and
* all other commercial damages or losses), even if such Contributor has been advised
* of the possibility of such damages.
*/
#include "BCTools.h"
#include "DebugUtilities.hpp"
namespace Diligent
{
inline void DecompressColorBlock(const Uint8* Bits,
Uint8* DstBuffer,
Uint32 DstChannels)
{
VERIFY_EXPR(DstChannels >= 3);
const Uint32 RGB[2] =
{
Uint32{Bits[0]} | ((Uint32{Bits[1]}) << 8),
Uint32{Bits[2]} | ((Uint32{Bits[3]}) << 8) //
};
static constexpr Uint32 ROffset = 11;
static constexpr Uint32 GOffset = 5;
static constexpr Uint32 BOffset = 0;
static constexpr Uint32 RMask = (1 << 5) - 1;
static constexpr Uint32 GMask = (1 << 6) - 1;
static constexpr Uint32 BMask = (1 << 5) - 1;
Uint32 R[4] = {(RGB[0] >> ROffset) & RMask, (RGB[1] >> ROffset) & RMask, 0, 0};
Uint32 G[4] = {(RGB[0] >> GOffset) & GMask, (RGB[1] >> GOffset) & GMask, 0, 0};
Uint32 B[4] = {(RGB[0] >> BOffset) & BMask, (RGB[1] >> BOffset) & BMask, 0, 0};
if (RGB[0] > RGB[1])
{
R[2] = (2 * R[0] + 1 * R[1]) / 3;
G[2] = (2 * G[0] + 1 * G[1]) / 3;
B[2] = (2 * B[0] + 1 * B[1]) / 3;
R[3] = (1 * R[0] + 2 * R[1]) / 3;
G[3] = (1 * G[0] + 2 * G[1]) / 3;
B[3] = (1 * B[0] + 2 * B[1]) / 3;
}
else
{
R[2] = (2 * R[0] + 1 * R[1]) / 2;
G[2] = (2 * G[0] + 1 * G[1]) / 2;
B[2] = (2 * B[0] + 1 * B[1]) / 2;
}
const Uint8* Palette = Bits + 4;
for (Uint32 i = 0; i < 16; ++i)
{
const Uint32 Idx = (Palette[i / 4u] >> ((i % 4u) * 2u)) & 0x03u;
DstBuffer[i * DstChannels + 0] = (R[Idx] << 3u) & 0xFFu;
DstBuffer[i * DstChannels + 1] = (G[Idx] << 2u) & 0xFFu;
DstBuffer[i * DstChannels + 2] = (B[Idx] << 3u) & 0xFFu;
}
}
inline void DecompressAlphaBlock(const Uint8* Bits,
Uint8* DstBuffer,
Uint32 DstChannels)
{
Uint32 Alpha[8] = {Bits[0], Bits[1]};
if (Alpha[0] > Alpha[1])
{
for (Uint32 i = 2; i < 8; ++i)
{
Alpha[i] = ((8 - i) * Alpha[0] + (i - 1) * Alpha[1]) / 7;
}
}
else
{
for (Uint32 i = 2; i < 6; ++i)
{
Alpha[i] = ((6 - i) * Alpha[0] + (i - 1) * Alpha[1]) / 5;
}
Alpha[6] = 0;
Alpha[7] = 255;
}
for (size_t p = 0; p < 2; ++p)
{
const Uint8* PaletteBits = Bits + 2 + p * 3;
const Uint32 Palette0 = Uint32{PaletteBits[0]} | (Uint32{PaletteBits[1]} << 8) | (Uint32{PaletteBits[2]} << 16);
for (Uint32 i = 0; i < 8; ++i)
{
Uint32 Idx = (Palette0 >> (i * 3)) & 0x07;
DstBuffer[(p * 8 + i) * DstChannels] = Alpha[Idx] & 0xFFu;
}
}
}
void DecompressBC1Block(const Uint8* Bits,
Uint8* DstBuffer,
Uint32 DstChannels)
{
VERIFY_EXPR(DstChannels >= 3);
DecompressColorBlock(Bits, DstBuffer, DstChannels);
}
void DecompressBC3Block(const Uint8* Bits,
Uint8* DstBuffer)
{
DecompressColorBlock(Bits + 8, DstBuffer, 4);
DecompressAlphaBlock(Bits, DstBuffer + 3, 4);
}
void DecompressBC4Block(const Uint8* Bits,
Uint8* DstBuffer,
Uint32 DstChannels)
{
VERIFY_EXPR(DstChannels >= 1);
DecompressAlphaBlock(Bits, DstBuffer, DstChannels);
}
void DecompressBC5lock(const Uint8* Bits,
Uint8* DstBuffer,
Uint32 DstChannels)
{
VERIFY_EXPR(DstChannels >= 2);
DecompressAlphaBlock(Bits, DstBuffer, DstChannels);
DecompressAlphaBlock(Bits + 8, DstBuffer + 1, DstChannels);
}
} // namespace Diligent