93 lines
2.7 KiB
C++
93 lines
2.7 KiB
C++
//
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// Created by Wouter Groeneveld on 14/12/18.
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//
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#include <libgba-sprite-engine/gbavector.h>
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GBAVector GBAVector::rotateAsCenter(GBAVector point, FIXED angle) {
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auto center = this->v;
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s32 centerx = center.x, centery = center.y;
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s32 defaultx = point.x(), defaulty = point.y();
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s32 cos = lu_cos(angle) >> 4;
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s32 sin = lu_sin(angle) >> 4;
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// affine matriches are 8.8 fixed point numbers, so shift all input 8 spaces up and forth
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// possibilities: instead of between [-1.0, 1.0] it's between [-256, +256]
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// 90° rotation in inversed y-axis needs to flip sin sign
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/*
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return GBAVector({
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( cos * (defaultx - centerx) + sin * (defaulty - centery) + (centerx << 8)) >> 8,
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(-sin * (defaultx - centerx) + cos * (defaulty - centery) + (centery << 8)) >> 8});
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*/
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return GBAVector({
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(fxmul(cos, (defaultx - centerx)) + fxmul(sin, (defaulty - centery)) + (centerx << 8)) >> 8,
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(fxmul(-sin, (defaultx - centerx)) + fxmul(cos, (defaulty - centery) + (centery << 8))) >> 8});
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}
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std::deque<VECTOR> GBAVector::bresenhamLineTo(VECTOR dest) {
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// https://www.coranac.com/tonc/text/bitmaps.htm - Bresenham's line algorithm with fixed points
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VECTOR src = this->v;
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VECTOR step, delta;
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std::deque<VECTOR> coords;
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if(src.x > dest.x) {
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step.x = -1;
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delta.x = (src.x - dest.x);
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} else {
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step.x = +1;
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delta.x = (dest.x - src.x);
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}
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if(src.y > dest.y) {
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step.y = -1;
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delta.y = (src.y - dest.y);
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} else {
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step.y = +1;
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delta.y = (dest.y - src.y);
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}
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int dd, x = src.x, y = src.y, ii;
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if(delta.y == 0) {
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// horizontal
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for(ii = 0; ii <= delta.x; ii++) {
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coords.push_back({x, y});
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x += step.x;
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}
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} else if(delta.x == 0) {
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// vertical
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for(ii = 0; ii <= delta.y; ii++) {
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coords.push_back({x, y});
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y += step.y;
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}
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} else if(delta.x >= delta.y) {
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// Diagonal, slope <= 1
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dd = 2 * delta.y - delta.x;
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for(ii = 0; ii <= delta.x; ii++) {
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coords.push_back({x, y});
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if(dd >= 0) {
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dd -= 2 * delta.x;
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y += step.y;
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}
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dd += 2 * delta.y;
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x += step.x;
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}
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} else {
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// Diagonal, slope > 1
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dd = 2 * delta.x - delta.y;
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for(ii = 0; ii <= delta.y; ii++) {
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coords.push_back({x, y});
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if(dd >= 0) {
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dd -= 2 * delta.y;
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x += step.x;
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}
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dd += 2 * delta.x;
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y += step.y;
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}
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}
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return coords;
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} |