/*
This function takes the RGB components of the image
and converts them into YCoCg. 3 components will be
re-ordered to CoYCg (for optimum DXT1 compression),
while 4 components will be ordered CoCgAY (for DXT5
compression).
*/
int
convert_RGB_to_YCoCg
(
unsigned char* orig,
int width, int height, int channels
)
{
int i;
/* error check */
if( (width < 1) || (height < 1) ||
(channels < 3) || (channels > 4) ||
(orig == NULL) )
{
/* nothing to do */
return -1;
}
/* do the conversion */
if( channels == 3 )
{
for( i = 0; i < width*height*3; i += 3 )
{
int r = orig[i+0];
int g = (orig[i+1] + 1) >> 1;
int b = orig[i+2];
int tmp = (2 + r + b) >> 2;
/* Co */
orig[i+0] = clamp_byte( 128 + ((r - b + 1) >> 1) );
/* Y */
orig[i+1] = clamp_byte( g + tmp );
/* Cg */
orig[i+2] = clamp_byte( 128 + g - tmp );
}
} else
{
for( i = 0; i < width*height*4; i += 4 )
void texture_draw(rs_texture_t *dest, rs_texture_t *src, int x, int y, int mode) {
int i; // y
int j; // x
int k; // color component
int istart = (y < 0) ? -y : 0;
int iend = src->h - (( (y + src->h) > dest->h) ? (y + src->h - dest->h) : 0);
int jstart = (x < 0) ? -x : 0;
int jend = src->w - (( (x + src->w) > dest->w) ? (x + src->w - dest->w) : 0);
int ishift = 0;
int jshift = 0;
float a; // alpha value
if (mode & DRAW_TILED_FLAG) {
jshift = x;
ishift = y;
x = y = istart = jstart = 0;
iend = dest->h;
jend = dest->w;
};
mode = mode & DRAW_MODE_MASK;
int modvalue = (src->w*src->h*4);
if (mode == DRAW_MODE_REPLACE) {
for (i = istart; i < iend; i++) {
for (j = jstart; j < jend; j++) {
for (k = 0; k < 4; k++) {
dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] = src->data[ (4*((i+ishift)*src->w + j + jshift) + k) % modvalue];
};
};
};
}
else if (mode == DRAW_MODE_ADDITIVE) {
for (i = istart; i < iend; i++) {
for (j = jstart; j < jend; j++) {
for (k = 0; k < 3; k++) { // Alpha channel is not added
dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] =
clamp_byte( dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] + src->data[ (4*((i+ishift)*src->w + j + jshift) + k) % modvalue] );
};
};
};
}
else if (mode == DRAW_MODE_MULT) {
for (i = istart; i < iend; i++) {
for (j = jstart; j < jend; j++) {
for (k = 0; k < 3; k++) { // Alpha channel is not added
dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] =
clamp_byte( dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] * src->data[ (4*((i+ishift)*src->w + j + jshift) + k) % modvalue] / 255 );
};
};
};
}
else if (mode == DRAW_MODE_ALPHA) {
for (i = istart; i < iend; i++) {
for (j = jstart; j < jend; j++) {
for (k = 0; k < 3; k++) {
a = (1.0 * src->data[ (4*(i*src->w + j) + 3) % modvalue ] / 255.0);
dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ] =
(unsigned char) ( (1.0-a) * dest->data[ 4 * ( (y+i)*dest->w + (x+j) ) + k ]
+ a*src->data[ (4*((i+ishift)*src->w + j + jshift) + k) % modvalue] );
};
};
};
};
};
