103 lines
2.6 KiB
C++
103 lines
2.6 KiB
C++
inline s32 RoundFloatToInt(float value)
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{
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return static_cast<s32>(value + 0.5);
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}
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struct V4: public ImVec4
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{
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using ImVec4::ImVec4;
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float &a = ImVec4::w;
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float &r = ImVec4::x;
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float &g = ImVec4::y;
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float &b = ImVec4::z;
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};
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inline u32 V4ToARGB(V4 c)
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{
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u32 result = ((RoundFloatToInt(c.a * 255.0) & 0xff) << 24
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| (RoundFloatToInt(c.r * 255.0) & 0xff) << 16
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| (RoundFloatToInt(c.g * 255.0) & 0xff) << 8
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| (RoundFloatToInt(c.b * 255.0) & 0xff) << 0);
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return result;
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}
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struct OffscreenBuffer
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{
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s32 width;
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s32 height;
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u8 *pixels;
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s32 pitch;
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const int BytesPerPixel;
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};
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inline void PutPixelUnchecked(OffscreenBuffer *buffer, s32 x, s32 y, V4 color)
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{
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u32 *pixel = reinterpret_cast<u32 *>(buffer->pixels
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+ y * buffer->pitch
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+ x * buffer->BytesPerPixel);
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*pixel = V4ToARGB(color);
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}
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inline void PutPixel(OffscreenBuffer *buffer, s32 x, s32 y, V4 color)
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{
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if (x >= 0 && x < buffer->width && y >= 0 && y < buffer->height)
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{
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PutPixelUnchecked(buffer, x, y, color);
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}
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}
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void DrawRectangle(OffscreenBuffer *buffer,
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float realMinX, float realMinY,
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float realMaxX, float realMaxY,
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V4 color)
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{
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s32 minX = RoundFloatToInt(realMinX);
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s32 minY = RoundFloatToInt(realMinY);
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s32 maxX = RoundFloatToInt(realMaxX);
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s32 maxY = RoundFloatToInt(realMaxY);
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if (minX < 0)
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minX = 0;
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if (minY < 0)
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minY = 0;
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if (maxX > buffer->width)
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maxX = buffer->width;
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if (maxY > buffer->height)
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maxY = buffer->height;
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u8 *row = buffer->pixels + minY * buffer->pitch;
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for (s32 y = minY; y < maxY; ++y)
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{
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u32 *dstPixel = reinterpret_cast<u32 *>(row + minX * buffer->BytesPerPixel);
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for (s32 x = minX; x < maxX; ++x)
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{
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float a = color.a;
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float srcR = color.r * 255.0;
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float srcG = color.g * 255.0;
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float srcB = color.b * 255.0;
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float dstR = ((*dstPixel >> 16) & 0xff);
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float dstG = ((*dstPixel >> 8) & 0xff);
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float dstB = ((*dstPixel >> 0) & 0xff);
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dstR = (1 - a) * dstR + a * srcR;
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dstG = (1 - a) * dstG + a * srcG;
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dstB = (1 - a) * dstB + a * srcB;
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*dstPixel = (RoundFloatToInt(dstR) << 16 |
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RoundFloatToInt(dstG) << 8 |
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RoundFloatToInt(dstB) << 0);
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++dstPixel;
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}
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row += buffer->pitch;
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}
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}
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