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Avoid divides in encode_scanline if not doing unpremultiply. 

Rename stb__encode_scanline to stb__encode_pixel
pull/32/head
Sean Barrett 2014-08-11 02:13:26 -07:00
parent a0537bfd04
commit 25fae8c67c
1 changed files with 20 additions and 23 deletions
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43
stb_resample.h
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@ -257,8 +257,8 @@ extern "C" {
#ifndef STBR_MALLOC #ifndef STBR_MALLOC
#include <stdlib.h> #include <stdlib.h>
#define STBR_MALLOC malloc #define STBR_MALLOC(x) malloc(x)
#define STBR_FREE free #define STBR_FREE(x) free(x)
#endif #endif
@ -1033,77 +1033,74 @@ static float* stbr__get_ring_buffer_scanline(int get_scanline, float* ring_buffe
} }
static stbr_inline void stbr__encode_scanline(void* output_buffer, int output_texel_index, float* encode_buffer, int encode_texel_index, int channels, int premul_alpha_channel, int decode) static stbr_inline void stbr__encode_pixel(void* output_buffer, int output_texel_index, float* encode_buffer, int encode_texel_index, int channels, int premul_alpha_channel, int decode)
{ {
int n; int n;
float divide_alpha = 1; float divide_alpha = 1;
if (premul_alpha_channel) if (premul_alpha_channel) {
divide_alpha = encode_buffer[encode_texel_index + premul_alpha_channel]; float alpha = encode_buffer[encode_texel_index + premul_alpha_channel];
float reciprocal_alpha = alpha ? 1.0 / alpha : 0;
for (n = 0; n < channels; n++)
if (n != premul_alpha_channel)
encode_buffer[encode_texel_index + n] *= reciprocal_alpha;
}
switch (decode) switch (decode)
{ {
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_LINEAR): case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_LINEAR):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned char*)output_buffer)[output_texel_index + n] = (unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 255);
((unsigned char*)output_buffer)[output_texel_index + n] = (unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel) * 255);
} }
break; break;
case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_SRGB): case STBR__DECODE(STBR_TYPE_UINT8, STBR_COLORSPACE_SRGB):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned char*)output_buffer)[output_texel_index + n] = stbr__linear_uchar_to_srgb_uchar[(unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 255)];
((unsigned char*)output_buffer)[output_texel_index + n] = stbr__linear_uchar_to_srgb_uchar[(unsigned char)(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel) * 255)];
} }
break; break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_LINEAR): case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_LINEAR):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)(stbr__saturate(encode_buffer[encode_texel_index + n]) * 65535);
((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel) * 65535);
} }
break; break;
case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_SRGB): case STBR__DECODE(STBR_TYPE_UINT16, STBR_COLORSPACE_SRGB):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)(stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n])) * 65535);
((unsigned short*)output_buffer)[output_texel_index + n] = (unsigned short)(stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel)) * 65535);
} }
break; break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_LINEAR): case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_LINEAR):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)(((double)stbr__saturate(encode_buffer[encode_texel_index + n])) * 4294967295);
((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)(((double)stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel)) * 4294967295);
} }
break; break;
case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_SRGB): case STBR__DECODE(STBR_TYPE_UINT32, STBR_COLORSPACE_SRGB):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)(((double)stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n]))) * 4294967295);
((unsigned int*)output_buffer)[output_texel_index + n] = (unsigned int)(((double)stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel))) * 4294967295);
} }
break; break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_LINEAR): case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_LINEAR):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((float*)output_buffer)[output_texel_index + n] = stbr__saturate(encode_buffer[encode_texel_index + n]);
((float*)output_buffer)[output_texel_index + n] = stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel);
} }
break; break;
case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_SRGB): case STBR__DECODE(STBR_TYPE_FLOAT, STBR_COLORSPACE_SRGB):
for (n = 0; n < channels; n++) for (n = 0; n < channels; n++)
{ {
float divide_alpha_channel = (n == premul_alpha_channel) ? 1 : divide_alpha; ((float*)output_buffer)[output_texel_index + n] = stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n]));
((float*)output_buffer)[output_texel_index + n] = stbr__linear_to_srgb(stbr__saturate(encode_buffer[encode_texel_index + n] / divide_alpha_channel));
} }
break; break;
@ -1168,7 +1165,7 @@ static void stbr__resample_vertical_upsample(stbr__info* stbr_info, int n, int i
encode_buffer[c] += ring_buffer_entry[in_texel_index + c] * coefficient; encode_buffer[c] += ring_buffer_entry[in_texel_index + c] * coefficient;
} }
stbr__encode_scanline(output_data, out_texel_index, encode_buffer, 0, channels, premul_alpha_channel, decode); stbr__encode_pixel(output_data, out_texel_index, encode_buffer, 0, channels, premul_alpha_channel, decode);
} }
} }
@ -1303,7 +1300,7 @@ static void stbr__empty_ring_buffer(stbr__info* stbr_info, int first_necessary_s
int ring_texel_index = texel_index; int ring_texel_index = texel_index;
int output_texel_index = output_row + texel_index; int output_texel_index = output_row + texel_index;
stbr__encode_scanline(output_data, output_texel_index, ring_buffer_entry, ring_texel_index, channels, premul_alpha_channel, decode); stbr__encode_pixel(output_data, output_texel_index, ring_buffer_entry, ring_texel_index, channels, premul_alpha_channel, decode);
} }
} }