39 lines
1.9 KiB
C++
39 lines
1.9 KiB
C++
#include "StarWorldCamera.hpp"
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namespace Star {
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void WorldCamera::setCenterWorldPosition(Vec2F const& position) {
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// Only actually move the world center if a half pixel distance has been
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// moved in any direction. This is sort of arbitrary, but helps prevent
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// judder if the camera is at a boundary and floating point inaccuracy is
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// causing the focus to jitter back and forth across the boundary.
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if (fabs(position[0] - m_worldCenter[0]) < 1.0f / (TilePixels * m_pixelRatio * 2) && fabs(position[1] - m_worldCenter[1]) < 1.0f / (TilePixels * m_pixelRatio * 2))
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return;
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// First, make sure the camera center position is inside the main x
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// coordinate bounds, and that the top and bototm of the screen are not
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// outside of the y coordinate bounds.
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m_worldCenter = m_worldGeometry.xwrap(position);
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m_worldCenter[1] = clamp(m_worldCenter[1],
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(float)m_screenSize[1] / (TilePixels * m_pixelRatio * 2),
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m_worldGeometry.height() - (float)m_screenSize[1] / (TilePixels * m_pixelRatio * 2));
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// Then, position the camera center position so that the tile grid is as
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// close as possible aligned to whole pixel boundaries. This is incredibly
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// important, because this means that even without any complicated rounding,
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// elements drawn in world space that are aligned with TilePixels will
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// eventually also be aligned to real screen pixels.
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if (m_screenSize[0] % 2 == 0)
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m_worldCenter[0] = round(m_worldCenter[0] * (TilePixels * m_pixelRatio)) / (TilePixels * m_pixelRatio);
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else
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m_worldCenter[0] = (round(m_worldCenter[0] * (TilePixels * m_pixelRatio) + 0.5f) - 0.5f) / (TilePixels * m_pixelRatio);
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if (m_screenSize[1] % 2 == 0)
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m_worldCenter[1] = round(m_worldCenter[1] * (TilePixels * m_pixelRatio)) / (TilePixels * m_pixelRatio);
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else
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m_worldCenter[1] = (round(m_worldCenter[1] * (TilePixels * m_pixelRatio) + 0.5f) - 0.5f) / (TilePixels * m_pixelRatio);
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}
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}
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