74 lines
2.8 KiB
C
74 lines
2.8 KiB
C
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struct unigi_ext_type_texture {
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unigi_type_resolution_2d_coord width;
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unigi_type_resolution_2d_coord height;
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unigi_type_color lq_color;
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unigi_type_color * pixels;
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};
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typedef struct unigi_ext_type_texture unigi_ext_type_texture;
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struct unigi_ext_type_rect {
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unigi_ext_type_2d_coord x1;
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unigi_ext_type_2d_coord y1;
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unigi_ext_type_2d_coord x2;
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unigi_ext_type_2d_coord y2;
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};
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typedef struct unigi_ext_type_rect unigi_ext_type_rect;
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void unigi_ext_rect_dimensions(
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unigi_ext_type_rect bounds,
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unigi_ext_type_2d_coord * width,
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unigi_ext_type_2d_coord * height
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) {
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*width = abs(bounds.x2 - bounds.x1);
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*height = abs(bounds.y2 - bounds.y1);
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}
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#define unigi_ext_texture_fixedpointdepth 8
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void unigi_ext_texture_draw(
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unigi_ext_type_texture tex,
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unigi_ext_type_texture buffer,
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unigi_ext_type_rect texbounds,
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unigi_ext_type_rect bufbounds
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) {
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unigi_ext_type_2d_coord texwidth;
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unigi_ext_type_2d_coord texheight;
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unigi_ext_type_2d_coord outwidth;
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unigi_ext_type_2d_coord outheight;
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unigi_ext_type_2d_coord x;
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unigi_ext_type_2d_coord y;
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unigi_type_resolution_1d_coord texi;
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unigi_type_resolution_1d_coord bufi;
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unigi_ext_type_2d_coord stepx;
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unigi_ext_type_2d_coord stepy;
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unigi_ext_type_2d_coord texx;
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unigi_ext_type_2d_coord texy;
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unigi_ext_rect_dimensions(texbounds, &texwidth, &texheight);
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unigi_ext_rect_dimensions(bufbounds, &outwidth, &outheight);
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// We precalculate the step through the texture to avoid division and
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// multiplication per pixel. We also expand the range so we can use
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// integers. By using 256, we are essentially adding 8 bits of "decimal
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// point". If you need more bits (or less), just change this to some other
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// power of 2.
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stepx = (1 << unigi_ext_texture_fixedpointdepth) * (float)texwidth / outwidth;
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stepy = (1 << unigi_ext_texture_fixedpointdepth) * (float)texheight / outheight;
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texx = (1 << unigi_ext_texture_fixedpointdepth) * texbounds.x1;
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texy = (1 << unigi_ext_texture_fixedpointdepth) * texbounds.y1;
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//log("%f,%f step %f,%f", texx, texy, stepx, stepy);
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// Buffer is R G B for each pixel, then across then down. If you want X, Y,
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// it's: 3 * (x + y * width)
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for(y = bufbounds.y1; y < bufbounds.y2; y++) {
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texx = texbounds.x1;
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for(x = bufbounds.x1; x < bufbounds.x2; x++) {
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// And then with the shift, it is log2(256), or whatever you shifted
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// by up there. So 512 would be 9, because 2^9 = 512
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texi = (texx >> unigi_ext_texture_fixedpointdepth) + tex.width * (texy >> unigi_ext_texture_fixedpointdepth); // 'texy >> FIXEDPOINTDEPTH' could be calculated per y-iteration
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bufi = x + y * buffer.width; // 'y * buffer.width' could be calculated per y-iteration
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buffer.pixels[bufi] = tex.pixels[texi];
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texx += stepx;
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bufi += 1;
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}
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texy += stepy;
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}
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}
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