#include "GLRGBScaler.hh"

#include "RenderSettings.hh"

#include "narrow.hh"

namespace openmsx {

GLRGBScaler::GLRGBScaler(

		RenderSettings& renderSettings_, GLScaler& fallback_)

	: GLScaler("rgb")

	, renderSettings(renderSettings_)

	, fallback(fallback_)

{

	for (auto i : xrange(2)) {

		program[i].activate();

		unifCnsts[i] = program[i].getUniformLocation("cnsts");

	}

}

void GLRGBScaler::scaleImage(

	gl::ColorTexture& src, gl::ColorTexture* superImpose,

	unsigned srcStartY, unsigned srcEndY, unsigned srcWidth,

	unsigned dstStartY, unsigned dstEndY, unsigned dstWidth,

	unsigned logSrcHeight)

{

	int i = superImpose ? 1 : 0;

	GLfloat blur = narrow<float>(renderSettings.getBlurFactor()) * (1.0f / 256.0f);

	GLfloat scanline = narrow<float>(renderSettings.getScanlineFactor()) * (1.0f / 255.0f);

	unsigned yScale = (dstEndY - dstStartY) / (srcEndY - srcStartY);

	if (yScale == 0) {

		// less lines in destination than in source

		// (factor=1 / interlace) --> disable scanlines

		scanline = 1.0f;

		yScale = 1;

	}

	if ((blur != 0.0f) || (scanline != 1.0f) || superImpose) {

		setup(superImpose != nullptr);

		if (srcWidth != 1) {

			// workaround for ATI cards

			src.setInterpolation(true);

		} else {

			// treat border as 256-pixel wide display area

			srcWidth = 320;

		}

		auto yScaleF = narrow<float>(yScale);

		GLfloat a = (yScale & 1) ? 0.5f : ((yScaleF + 1.0f) / (2.0f * yScaleF));

		GLfloat c1 = blur;

		GLfloat c2 = 3.0f - 2.0f * c1;

		glUniform4f(unifCnsts[i],

		            a,                             // scan_a

		            (1.0f - scanline) * 2.0f * c2, // scan_b_c2

		            scanline * c2,                 // scan_c_c2

		            (c1 - c2) / c2);               // scan_c1_2_2

		execute(src, superImpose,

		        srcStartY, srcEndY, srcWidth,

		        dstStartY, dstEndY, dstWidth,

		        logSrcHeight);

		src.setInterpolation(false);

	} else {

		fallback.scaleImage(src, superImpose,

		                    srcStartY, srcEndY, srcWidth,

		                    dstStartY, dstEndY, dstWidth,

		                    logSrcHeight);

	}

}

} // namespace openmsx