#include "GLSimpleScaler.hh"

#include "RenderSettings.hh"

#include "narrow.hh"

#include "xrange.hh"

namespace openmsx {

GLSimpleScaler::GLSimpleScaler(

		RenderSettings& renderSettings_, GLScaler& fallback_)

	: GLScaler("simple")

	, renderSettings(renderSettings_)

	, fallback(fallback_)

{

	for (auto i : xrange(2)) {

		program[i].activate();

		unifTexStepX[i] = program[i].getUniformLocation("texStepX");

		unifCnst[i]     = program[i].getUniformLocation("cnst");

	}

}

void GLSimpleScaler::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 ((blur != 0.0f) && (srcWidth != 1)) { // srcWidth check: workaround for ATI cards

			src.setInterpolation(true);

		}

		auto yScaleF = narrow<GLfloat>(yScale);

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

		GLfloat scan_b = 2.0f - 2.0f * scanline;

		GLfloat scan_c = scanline;

		if (!superImpose) {

			// small optimization in simple.frag:

			// divide by 2 here instead of on every pixel

			scan_b *= 0.5f;

			scan_c *= 0.5f;

		}

		auto recipSrcWidth = 1.0f / narrow<float>(srcWidth);

		glUniform3f(unifTexStepX[i], recipSrcWidth, recipSrcWidth, 0.0f);

		glUniform4f(unifCnst[i], scan_a, scan_b, scan_c, blur);

		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