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124 lines
3.5 KiB
C++
124 lines
3.5 KiB
C++
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#include "graphics/tinygl/zgl.h"
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namespace TinyGL {
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// linear interpolation with xf, yf normalized to 2^16
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#define INTERP_NORM_BITS 16
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#define INTERP_NORM (1 << INTERP_NORM_BITS)
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static inline int interpolate(int v00, int v01, int v10, int xf, int yf) {
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return v00 + (((v01 - v00) * xf + (v10 - v00) * yf) >> INTERP_NORM_BITS);
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}
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// TODO: more accurate resampling
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void gl_resizeImage(unsigned char *dest, int xsize_dest, int ysize_dest,
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unsigned char *src, int xsize_src, int ysize_src) {
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unsigned char *pix, *pix_src;
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int point1_offset = 0, point2_offset = 0, point3_offset = 0;
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float x1, y1, x1inc, y1inc;
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int xi, yi, xf, yf;
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pix = dest;
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pix_src = src;
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x1inc = (float)(xsize_src - 1) / (float)(xsize_dest - 1);
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y1inc = (float)(ysize_src - 1) / (float)(ysize_dest - 1);
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y1 = 0;
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for (int y = 0; y < ysize_dest; y++) {
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x1 = 0;
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for (int x = 0; x < xsize_dest; x++) {
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xi = (int)x1;
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yi = (int)y1;
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xf = (int)((x1 - floor(x1)) * INTERP_NORM);
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yf = (int)((y1 - floor(y1)) * INTERP_NORM);
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if ((xf + yf) <= INTERP_NORM) {
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for (int j = 0; j < 3; j++) {
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point1_offset = (yi * xsize_src + xi) * 4 + j;
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if ((xi + 1) < xsize_src)
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point2_offset = (yi * xsize_src + xi + 1) * 4 + j;
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else
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point2_offset = point1_offset;
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if ((yi + 1) < ysize_src)
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point3_offset = ((yi + 1) * xsize_src + xi) * 4 + j;
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else
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point3_offset = point1_offset;
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pix[j] = interpolate(pix_src[point1_offset], pix_src[point2_offset], pix_src[point3_offset], xf, yf);
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}
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pix[3] = pix_src[(yi * xsize_src + xi) * 4 + 3];
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} else {
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xf = INTERP_NORM - xf;
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yf = INTERP_NORM - yf;
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for (int j = 0; j < 3; j++) {
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pix[j] = interpolate(pix_src[point1_offset], pix_src[point2_offset], pix_src[point3_offset], xf, yf);
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if ((xi + 1) < xsize_src) {
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if ((yi + 1) < ysize_src)
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point1_offset = ((yi + 1) * xsize_src + xi + 1) * 4 + j;
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else
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point1_offset = (yi * xsize_src + xi + 1) * 4 + j;
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} else {
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if ((yi + 1) < ysize_src)
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point1_offset = ((yi + 1) * xsize_src + xi) * 4 + j;
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else
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point1_offset = (yi * xsize_src + xi) * 4 + j;
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}
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if ((yi + 1) < ysize_src)
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point2_offset = ((yi + 1) * xsize_src + xi) * 4 + j;
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else
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point2_offset = (yi * xsize_src + xi) * 4 + j;
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if ((xi + 1) < xsize_src)
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point3_offset = (yi * xsize_src + xi + 1) * 4 + j;
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else
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point3_offset = (yi * xsize_src + xi) * 4 + j;
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pix[j] = interpolate(pix_src[point1_offset], pix_src[point2_offset], pix_src[point3_offset], xf, yf);
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}
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pix[3] = pix_src[(yi * xsize_src + xi) * 4 + 3];
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}
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pix += 4;
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x1 += x1inc;
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}
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y1 += y1inc;
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}
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}
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#define FRAC_BITS 16
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// resizing with no interlating nor nearest pixel
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void gl_resizeImageNoInterpolate(unsigned char *dest, int xsize_dest, int ysize_dest,
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unsigned char *src, int xsize_src, int ysize_src) {
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unsigned char *pix, *pix_src, *pix1;
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int x1, y1, x1inc, y1inc;
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int xi, yi;
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pix = dest;
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pix_src = src;
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x1inc = (int)((float)((xsize_src) << FRAC_BITS) / (float)(xsize_dest));
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y1inc = (int)((float)((ysize_src) << FRAC_BITS) / (float)(ysize_dest));
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y1 = 0;
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for (int y = 0; y < ysize_dest; y++) {
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x1 = 0;
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for (int x = 0; x < xsize_dest; x++) {
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xi = x1 >> FRAC_BITS;
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yi = y1 >> FRAC_BITS;
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pix1 = pix_src + (yi * xsize_src + xi) * 4;
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pix[0] = pix1[0];
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pix[1] = pix1[1];
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pix[2] = pix1[2];
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pix[3] = pix1[3];
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pix += 4;
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x1 += x1inc;
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}
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y1 += y1inc;
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}
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}
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} // end of namespace TinyGL
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