263 lines
9.1 KiB
GLSL
263 lines
9.1 KiB
GLSL
/* OmniScale is derived from the pattern based design of HQnx, but with the following general differences:
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- The actual output calculating was completely redesigned as resolution independent graphic generator. This allows
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scaling to any factor.
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- HQnx approximations that were good enough for a 2x/3x/4x factor were refined, creating smoother gradients.
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- "Quarters" can be interpolated in more ways than in the HQnx filters
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- If a pattern does not provide enough information to determine the suitable scaling interpolation, up to 16 pixels
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per quarter are sampled (in contrast to the usual 9) in order to determine the best interpolation.
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*/
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/* We use the same colorspace as the HQ algorithms. */
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STATIC vec3 rgb_to_hq_colospace(vec4 rgb)
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{
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return vec3( 0.250 * rgb.r + 0.250 * rgb.g + 0.250 * rgb.b,
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0.250 * rgb.r - 0.000 * rgb.g - 0.250 * rgb.b,
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-0.125 * rgb.r + 0.250 * rgb.g - 0.125 * rgb.b);
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}
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STATIC bool is_different(vec4 a, vec4 b)
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{
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vec3 diff = abs(rgb_to_hq_colospace(a) - rgb_to_hq_colospace(b));
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return diff.x > 0.125 || diff.y > 0.027 || diff.z > 0.031;
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}
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#define P(m, r) ((pattern & (m)) == (r))
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STATIC vec4 scale(sampler2D image, vec2 position, vec2 input_resolution, vec2 output_resolution)
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{
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// o = offset, the width of a pixel
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vec2 o = 1.0 / input_resolution;
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/* We always calculate the top left quarter. If we need a different quarter, we flip our co-ordinates */
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// p = the position within a pixel [0...1]
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vec2 p = fract(position * input_resolution);
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if (p.x > 0.5) {
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o.x = -o.x;
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p.x = 1.0 - p.x;
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}
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if (p.y > 0.5) {
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o.y = -o.y;
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p.y = 1.0 - p.y;
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}
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vec4 w0 = texture(image, position + vec2( -o.x, -o.y));
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vec4 w1 = texture(image, position + vec2( 0, -o.y));
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vec4 w2 = texture(image, position + vec2( o.x, -o.y));
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vec4 w3 = texture(image, position + vec2( -o.x, 0));
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vec4 w4 = texture(image, position + vec2( 0, 0));
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vec4 w5 = texture(image, position + vec2( o.x, 0));
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vec4 w6 = texture(image, position + vec2( -o.x, o.y));
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vec4 w7 = texture(image, position + vec2( 0, o.y));
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vec4 w8 = texture(image, position + vec2( o.x, o.y));
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int pattern = 0;
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if (is_different(w0, w4)) pattern |= 1 << 0;
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if (is_different(w1, w4)) pattern |= 1 << 1;
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if (is_different(w2, w4)) pattern |= 1 << 2;
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if (is_different(w3, w4)) pattern |= 1 << 3;
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if (is_different(w5, w4)) pattern |= 1 << 4;
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if (is_different(w6, w4)) pattern |= 1 << 5;
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if (is_different(w7, w4)) pattern |= 1 << 6;
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if (is_different(w8, w4)) pattern |= 1 << 7;
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if ((P(0xbf,0x37) || P(0xdb,0x13)) && is_different(w1, w5)) {
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return mix(w4, w3, 0.5 - p.x);
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}
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if ((P(0xdb,0x49) || P(0xef,0x6d)) && is_different(w7, w3)) {
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return mix(w4, w1, 0.5 - p.y);
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}
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if ((P(0x0b,0x0b) || P(0xfe,0x4a) || P(0xfe,0x1a)) && is_different(w3, w1)) {
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return w4;
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}
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if ((P(0x6f,0x2a) || P(0x5b,0x0a) || P(0xbf,0x3a) || P(0xdf,0x5a) ||
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P(0x9f,0x8a) || P(0xcf,0x8a) || P(0xef,0x4e) || P(0x3f,0x0e) ||
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P(0xfb,0x5a) || P(0xbb,0x8a) || P(0x7f,0x5a) || P(0xaf,0x8a) ||
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P(0xeb,0x8a)) && is_different(w3, w1)) {
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return mix(w4, mix(w4, w0, 0.5 - p.x), 0.5 - p.y);
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}
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if (P(0x0b,0x08)) {
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return mix(mix(w0 * 0.375 + w1 * 0.25 + w4 * 0.375, w4 * 0.5 + w1 * 0.5, p.x * 2.0), w4, p.y * 2.0);
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}
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if (P(0x0b,0x02)) {
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return mix(mix(w0 * 0.375 + w3 * 0.25 + w4 * 0.375, w4 * 0.5 + w3 * 0.5, p.y * 2.0), w4, p.x * 2.0);
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}
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if (P(0x2f,0x2f)) {
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float dist = length(p - vec2(0.5));
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float pixel_size = length(1.0 / (output_resolution / input_resolution));
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if (dist < 0.5 - pixel_size / 2) {
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return w4;
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}
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vec4 r;
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if (is_different(w0, w1) || is_different(w0, w3)) {
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r = mix(w1, w3, p.y - p.x + 0.5);
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}
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else {
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r = mix(mix(w1 * 0.375 + w0 * 0.25 + w3 * 0.375, w3, p.y * 2.0), w1, p.x * 2.0);
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}
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if (dist > 0.5 + pixel_size / 2) {
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return r;
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}
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return mix(w4, r, (dist - 0.5 + pixel_size / 2) / pixel_size);
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}
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if (P(0xbf,0x37) || P(0xdb,0x13)) {
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float dist = p.x - 2.0 * p.y;
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float pixel_size = length(1.0 / (output_resolution / input_resolution)) * sqrt(5.0);
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if (dist > pixel_size / 2) {
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return w1;
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}
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vec4 r = mix(w3, w4, p.x + 0.5);
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if (dist < -pixel_size / 2) {
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return r;
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}
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return mix(r, w1, (dist + pixel_size / 2) / pixel_size);
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}
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if (P(0xdb,0x49) || P(0xef,0x6d)) {
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float dist = p.y - 2.0 * p.x;
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float pixel_size = length(1.0 / (output_resolution / input_resolution)) * sqrt(5.0);
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if (p.y - 2.0 * p.x > pixel_size / 2) {
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return w3;
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}
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vec4 r = mix(w1, w4, p.x + 0.5);
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if (dist < -pixel_size / 2) {
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return r;
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}
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return mix(r, w3, (dist + pixel_size / 2) / pixel_size);
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}
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if (P(0xbf,0x8f) || P(0x7e,0x0e)) {
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float dist = p.x + 2.0 * p.y;
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float pixel_size = length(1.0 / (output_resolution / input_resolution)) * sqrt(5.0);
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if (dist > 1.0 + pixel_size / 2) {
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return w4;
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}
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vec4 r;
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if (is_different(w0, w1) || is_different(w0, w3)) {
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r = mix(w1, w3, p.y - p.x + 0.5);
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}
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else {
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r = mix(mix(w1 * 0.375 + w0 * 0.25 + w3 * 0.375, w3, p.y * 2.0), w1, p.x * 2.0);
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}
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if (dist < 1.0 - pixel_size / 2) {
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return r;
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}
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return mix(r, w4, (dist + pixel_size / 2 - 1.0) / pixel_size);
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}
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if (P(0x7e,0x2a) || P(0xef,0xab)) {
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float dist = p.y + 2.0 * p.x;
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float pixel_size = length(1.0 / (output_resolution / input_resolution)) * sqrt(5.0);
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if (p.y + 2.0 * p.x > 1.0 + pixel_size / 2) {
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return w4;
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}
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vec4 r;
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if (is_different(w0, w1) || is_different(w0, w3)) {
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r = mix(w1, w3, p.y - p.x + 0.5);
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}
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else {
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r = mix(mix(w1 * 0.375 + w0 * 0.25 + w3 * 0.375, w3, p.y * 2.0), w1, p.x * 2.0);
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}
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if (dist < 1.0 - pixel_size / 2) {
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return r;
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}
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return mix(r, w4, (dist + pixel_size / 2 - 1.0) / pixel_size);
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}
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if (P(0x1b,0x03) || P(0x4f,0x43) || P(0x8b,0x83) || P(0x6b,0x43)) {
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return mix(w4, w3, 0.5 - p.x);
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}
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if (P(0x4b,0x09) || P(0x8b,0x89) || P(0x1f,0x19) || P(0x3b,0x19)) {
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return mix(w4, w1, 0.5 - p.y);
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}
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if (P(0xfb,0x6a) || P(0x6f,0x6e) || P(0x3f,0x3e) || P(0xfb,0xfa) ||
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P(0xdf,0xde) || P(0xdf,0x1e)) {
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return mix(w4, w0, (1.0 - p.x - p.y) / 2.0);
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}
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if (P(0x4f,0x4b) || P(0x9f,0x1b) || P(0x2f,0x0b) ||
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P(0xbe,0x0a) || P(0xee,0x0a) || P(0x7e,0x0a) || P(0xeb,0x4b) ||
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P(0x3b,0x1b)) {
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float dist = p.x + p.y;
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float pixel_size = length(1.0 / (output_resolution / input_resolution));
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if (dist > 0.5 + pixel_size / 2) {
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return w4;
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}
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vec4 r;
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if (is_different(w0, w1) || is_different(w0, w3)) {
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r = mix(w1, w3, p.y - p.x + 0.5);
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}
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else {
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r = mix(mix(w1 * 0.375 + w0 * 0.25 + w3 * 0.375, w3, p.y * 2.0), w1, p.x * 2.0);
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}
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if (dist < 0.5 - pixel_size / 2) {
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return r;
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}
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return mix(r, w4, (dist + pixel_size / 2 - 0.5) / pixel_size);
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}
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if (P(0x0b,0x01)) {
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return mix(mix(w4, w3, 0.5 - p.x), mix(w1, (w1 + w3) / 2.0, 0.5 - p.x), 0.5 - p.y);
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}
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if (P(0x0b,0x00)) {
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return mix(mix(w4, w3, 0.5 - p.x), mix(w1, w0, 0.5 - p.x), 0.5 - p.y);
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}
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float dist = p.x + p.y;
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float pixel_size = length(1.0 / (output_resolution / input_resolution));
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if (dist > 0.5 + pixel_size / 2) {
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return w4;
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}
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/* We need more samples to "solve" this diagonal */
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vec4 x0 = texture(image, position + vec2( -o.x * 2.0, -o.y * 2.0));
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vec4 x1 = texture(image, position + vec2( -o.x , -o.y * 2.0));
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vec4 x2 = texture(image, position + vec2( 0.0 , -o.y * 2.0));
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vec4 x3 = texture(image, position + vec2( o.x , -o.y * 2.0));
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vec4 x4 = texture(image, position + vec2( -o.x * 2.0, -o.y ));
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vec4 x5 = texture(image, position + vec2( -o.x * 2.0, 0.0 ));
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vec4 x6 = texture(image, position + vec2( -o.x * 2.0, o.y ));
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if (is_different(x0, w4)) pattern |= 1 << 8;
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if (is_different(x1, w4)) pattern |= 1 << 9;
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if (is_different(x2, w4)) pattern |= 1 << 10;
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if (is_different(x3, w4)) pattern |= 1 << 11;
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if (is_different(x4, w4)) pattern |= 1 << 12;
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if (is_different(x5, w4)) pattern |= 1 << 13;
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if (is_different(x6, w4)) pattern |= 1 << 14;
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int diagonal_bias = -7;
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while (pattern != 0) {
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diagonal_bias += pattern & 1;
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pattern >>= 1;
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}
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if (diagonal_bias <= 0) {
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vec4 r = mix(w1, w3, p.y - p.x + 0.5);
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if (dist < 0.5 - pixel_size / 2) {
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return r;
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}
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return mix(r, w4, (dist + pixel_size / 2 - 0.5) / pixel_size);
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}
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return w4;
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}
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