Connor Worley:
> For future use in lavc/dxvenc.
>
> Signed-off-by: Connor Worley <connorbwor...@gmail.com>
> ---
> libavcodec/texturedsp.h | 1 +
> libavcodec/texturedspenc.c | 41 ++++++++++++++++++++++++++++++++++++++
> 2 files changed, 42 insertions(+)
>
> diff --git a/libavcodec/texturedsp.h b/libavcodec/texturedsp.h
> index 86c8eea02d..8881436187 100644
> --- a/libavcodec/texturedsp.h
> +++ b/libavcodec/texturedsp.h
> @@ -62,6 +62,7 @@ typedef struct TextureDSPContext {
>
> typedef struct TextureDSPEncContext {
> int (*dxt1_block) (uint8_t *dst, ptrdiff_t stride, const uint8_t
> *block);
> + int (*dxt4_block) (uint8_t *dst, ptrdiff_t stride, const uint8_t
> *block);
> int (*dxt5_block) (uint8_t *dst, ptrdiff_t stride, const uint8_t
> *block);
> int (*dxt5ys_block) (uint8_t *dst, ptrdiff_t stride, const uint8_t
> *block);
> } TextureDSPEncContext;
> diff --git a/libavcodec/texturedspenc.c b/libavcodec/texturedspenc.c
> index 5657a6ef61..c98a277f56 100644
> --- a/libavcodec/texturedspenc.c
> +++ b/libavcodec/texturedspenc.c
> @@ -589,6 +589,20 @@ static void rgba2ycocg(uint8_t *dst, const uint8_t
> *pixel)
> dst[3] = av_clip_uint8(g + t); /* Y */
> }
>
> +/** Convert a straight alpha pixel to a premultiplied alpha pixel. */
> +static av_always_inline void straight2premult(uint8_t *dst, const uint8_t
> *src)
> +{
> + const int r = src[0];
> + const int g = src[1];
> + const int b = src[2];
> + const int a = src[3]; /* unchanged */
> +
> + dst[0] = (uint8_t) r * a / 255;
> + dst[1] = (uint8_t) g * a / 255;
> + dst[2] = (uint8_t) b * a / 255;
> + dst[3] = a;
> +}
> +
> /**
> * Compress one block of RGBA pixels in a DXT1 texture and store the
> * resulting bytes in 'dst'. Alpha is not preserved.
> @@ -605,6 +619,32 @@ static int dxt1_block(uint8_t *dst, ptrdiff_t stride,
> const uint8_t *block)
> return 8;
> }
>
> +/**
> + * Compress one block of RGBA pixels in a DXT4 texture and store the
> + * resulting bytes in 'dst'. Alpha is preserved.
> + *
> + * @param dst output buffer.
> + * @param stride scanline in bytes.
> + * @param block block to compress.
> + * @return how much texture data has been written.
> + */
> +static int dxt4_block(uint8_t *dst, ptrdiff_t stride, const uint8_t *block)
> +{
> + int x, y;
> + uint8_t premult[64];
> +
> + for (y = 0; y < 4; y++) {
> + for (x = 0; x < 4; x++) {
> + straight2premult(premult + x * 4 + y * 16, block + x * 4 + y *
> stride);
> + }
> + }
> +
> + compress_alpha(dst, 16, premult);
> + compress_color(dst + 8, 16, premult);
> +
> + return 16;
> +}
> +
> /**
> * Compress one block of RGBA pixels in a DXT5 texture and store the
> * resulting bytes in 'dst'. Alpha is preserved.
> @@ -650,6 +690,7 @@ static int dxt5ys_block(uint8_t *dst, ptrdiff_t stride,
> const uint8_t *block)
> av_cold void ff_texturedspenc_init(TextureDSPEncContext *c)
> {
> c->dxt1_block = dxt1_block;
> + c->dxt4_block = dxt4_block;
> c->dxt5_block = dxt5_block;
> c->dxt5ys_block = dxt5ys_block;
> }
This should be added in a patchset that actually makes use of it to
avoid the fate of rgtc1_u_alpha.
- Andreas
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