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◆ main openmsx / src / video / scalers / GLScaler.hh
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#ifndef GLSCALER_HH
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#define GLSCALER_HH
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#include "GLUtil.hh"
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#include <array>
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#include <string>
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namespace openmsx {
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class FrameSource;
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/** Abstract base class for OpenGL scalers.
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  * A scaler is an algorithm that converts low-res graphics to hi-res graphics.
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  */
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class GLScaler
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{
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public:
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	virtual ~GLScaler() = default;
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	/** Setup scaler.
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	  * Must be called once per frame before calling scaleImage() (possibly
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	  * multiple times).
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	  */
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	void setup(bool superImpose);
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	/** Scales the image in the given area, which must consist of lines which
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	  * are all equally wide.
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	  * Scaling factor depends on the concrete scaler.
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	  * @param src Source: texture containing the frame to be scaled.
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	  * @param superImpose Texture containing the to-be-superimposed image (can be nullptr).
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	  * @param srcStartY Y-coordinate of the top source line (inclusive).
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	  * @param srcEndY Y-coordinate of the bottom source line (exclusive).
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	  * @param srcWidth The number of pixels per line for the given area.
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	  * @param dstStartY Y-coordinate of the top destination line (inclusive).
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	  * @param dstEndY Y-coordinate of the bottom destination line (exclusive).
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	  * @param dstWidth The number of pixels per line on the output screen.
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	  * @param logSrcHeight The logical height of the complete src texture
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	  *        (actual texture height can be double as high in case of
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	  *        non-interlace). This is needed to translate src-Y-coordinates
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	  *        to superImpose-Y-coordinates.
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	  */
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	virtual void scaleImage(
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		gl::ColorTexture& src, gl::ColorTexture* superImpose,
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		unsigned srcStartY, unsigned srcEndY, unsigned srcWidth,
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		unsigned dstStartY, unsigned dstEndY, unsigned dstWidth,
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		unsigned logSrcHeight) = 0;
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	virtual void uploadBlock(
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		unsigned srcStartY, unsigned srcEndY,
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		unsigned lineWidth, FrameSource& paintFrame);
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protected:
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	explicit GLScaler(const std::string& progName);
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	/** Helper method to draw a rectangle with multiple texture coordinates.
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	  * This method is similar to Texture::drawRect() but it calculates a
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	  * seconds set of texture coordinates. The first tex-coords are used
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	  * for the MSX texture (texture unit 0), and are calculated from
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	  * src{Start,End}Y and src.getHeight(). The second set of tex-coord are
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	  * used for the superimpose texture (texture unit 1) and are calculated
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	  * from src{Start,End}Y and logSrcHeight.
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	  * @param src
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	  * @param superImpose
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	  * @param srcStartY
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	  * @param srcEndY
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	  * @param srcWidth
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	  * @param dstStartY
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	  * @param dstEndY
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	  * @param dstWidth
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	  * @param logSrcHeight
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	  * @param textureFromZero If true, the texture coordinates of subpixels
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	  *   will start from zero: for example in 4x zoom the source coordinates
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	  *   will be 0.0, 0.25, 0.5, 0.75. If false, the texture coordinates of
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	  *   subpixels will be centered: for example in 4x zoom the source
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	  *   coordinates will be 0.125, 0.375, 0.625, 0.875.
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	  */
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	void execute(const gl::ColorTexture& src, const gl::ColorTexture* superImpose,
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	             unsigned srcStartY, unsigned srcEndY, unsigned srcWidth,
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	             unsigned dstStartY, unsigned dstEndY, unsigned dstWidth,
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	             unsigned logSrcHeight,
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	             bool textureFromZero = false);
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protected:
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	std::array<gl::BufferObject, 2> vbo;
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	std::array<gl::ShaderProgram, 2> program;
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	std::array<GLint, 2> unifTexSize;
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	std::array<GLint, 2> unifMvpMatrix;
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};
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} // namespace openmsx
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#endif // GLSCALER_HH