Bresenham's circle algorithm.
| 900 | |
| 901 | // Bresenham's circle algorithm. |
| 902 | static void drawCircle(const RenderTarget& rt, const Ui::Point& centre, int32_t radius, int32_t lineWidth, const PaletteIndex_t colour) |
| 903 | { |
| 904 | if (radius <= 0 || lineWidth <= 0) |
| 905 | { |
| 906 | return; |
| 907 | } |
| 908 | |
| 909 | // Check if circle is completely outside the render target |
| 910 | const auto rtRect = rt.getUiRect(); |
| 911 | const auto outerRadius = radius + lineWidth - 1; |
| 912 | if (centre.x + outerRadius < rtRect.left() |
| 913 | || centre.x - outerRadius >= rtRect.right() |
| 914 | || centre.y + outerRadius < rtRect.top() |
| 915 | || centre.y - outerRadius >= rtRect.bottom()) |
| 916 | { |
| 917 | return; |
| 918 | } |
| 919 | |
| 920 | const auto innerRadius = std::max(0, radius - lineWidth + 1); |
| 921 | for (auto currentRadius = innerRadius; currentRadius <= radius; ++currentRadius) |
| 922 | { |
| 923 | int16_t x = 0; |
| 924 | int16_t y = currentRadius; |
| 925 | int16_t decision = 1 - currentRadius; |
| 926 | |
| 927 | const auto drawCirclePoints = [&](int16_t offsetX, int16_t offsetY) { |
| 928 | drawHorizontalLine(rt, colour, { centre.x + offsetX, centre.y + offsetY }, 1); |
| 929 | drawHorizontalLine(rt, colour, { centre.x - offsetX, centre.y + offsetY }, 1); |
| 930 | drawHorizontalLine(rt, colour, { centre.x + offsetX, centre.y - offsetY }, 1); |
| 931 | drawHorizontalLine(rt, colour, { centre.x - offsetX, centre.y - offsetY }, 1); |
| 932 | drawHorizontalLine(rt, colour, { centre.x + offsetY, centre.y + offsetX }, 1); |
| 933 | drawHorizontalLine(rt, colour, { centre.x - offsetY, centre.y + offsetX }, 1); |
| 934 | drawHorizontalLine(rt, colour, { centre.x + offsetY, centre.y - offsetX }, 1); |
| 935 | drawHorizontalLine(rt, colour, { centre.x - offsetY, centre.y - offsetX }, 1); |
| 936 | }; |
| 937 | |
| 938 | while (x <= y) |
| 939 | { |
| 940 | drawCirclePoints(x, y); |
| 941 | |
| 942 | if (decision < 0) |
| 943 | { |
| 944 | decision += 2 * x + 3; |
| 945 | } |
| 946 | else |
| 947 | { |
| 948 | decision += 2 * (x - y) + 5; |
| 949 | y--; |
| 950 | } |
| 951 | x++; |
| 952 | } |
| 953 | } |
| 954 | } |
| 955 | |
| 956 | // 0x00452DA4 |
| 957 | static void drawLine(const RenderTarget& rt, Ui::Point a, Ui::Point b, const PaletteIndex_t colour) |
no test coverage detected