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◆ main openmsx / src / video / scalers / GLScaler.cc
3.7 KiB · C++ · last changed chore(): initial commit 1 month ago source blame history raw
e8555c89 Andy McCall 1 
#include "GLScaler.hh"
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#include "GLContext.hh"
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#include "gl_vec.hh"
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#include "narrow.hh"
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#include "strCat.hh"
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#include "xrange.hh"
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using namespace gl;
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namespace openmsx {
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GLScaler::GLScaler(const std::string& progName)
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{
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	for (auto i : xrange(2)) {
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		auto header = tmpStrCat("#define SUPERIMPOSE ", char('0' + i), '\n');
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		VertexShader   vShader(header, progName + ".vert");
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		FragmentShader fShader(header, progName + ".frag");
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		program[i].attach(vShader);
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		program[i].attach(fShader);
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		program[i].bindAttribLocation(0, "a_position");
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		program[i].bindAttribLocation(1, "a_texCoord");
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		program[i].link();
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		program[i].activate();
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		glUniform1i(program[i].getUniformLocation("tex"), 0);
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		if (i == 1) {
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			glUniform1i(program[i].getUniformLocation("videoTex"), 1);
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		}
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		unifTexSize[i] = program[i].getUniformLocation("texSize");
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		unifMvpMatrix[i] = program[i].getUniformLocation("u_mvpMatrix");
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	}
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}
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void GLScaler::uploadBlock(
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	unsigned /*srcStartY*/, unsigned /*srcEndY*/,
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	unsigned /*lineWidth*/, FrameSource& /*paintFrame*/)
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{
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}
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void GLScaler::setup(bool superImpose)
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{
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	int i = superImpose ? 1 : 0;
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	program[i].activate();
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	glUniformMatrix4fv(unifMvpMatrix[i], 1, GL_FALSE, gl::context->pixelMvp.data());
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}
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void GLScaler::execute(
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	const ColorTexture& src, const 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, bool textureFromZero)
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{
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	auto srcStartYF = narrow<float>(srcStartY);
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	auto srcEndYF = narrow<float>(srcEndY);
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	auto dstStartYF = narrow<float>(dstStartY);
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	auto dstEndYF = narrow<float>(dstEndY);
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	auto dstWidthF = narrow<float>(dstWidth);
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	auto srcWidthF = narrow<float>(srcWidth);
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	auto srcHeightF = narrow<float>(src.getHeight());
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	auto logSrcHeightF = narrow<float>(logSrcHeight);
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	if (superImpose) {
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		glActiveTexture(GL_TEXTURE1);
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		superImpose->bind();
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		glActiveTexture(GL_TEXTURE0);
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	}
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	int i = superImpose ? 1 : 0;
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	glUniform3f(unifTexSize[i], srcWidthF, srcHeightF, logSrcHeightF);
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	src.bind();
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	// Note: hShift is pre-divided by srcWidth, while vShift will be divided
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	//       by srcHeight later on.
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	// Note: The coordinate is put just past zero, to avoid fract() in the
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	//       fragment shader to wrap around on rounding errors.
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	static constexpr float BIAS = 0.001f;
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	float samplePos = (textureFromZero ? 0.5f : 0.0f) + BIAS;
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	float hShift = samplePos / dstWidthF;
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	float yRatio = (srcEndYF - srcStartYF) / (dstEndYF - dstStartYF);
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	float vShift = samplePos * yRatio;
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	// vertex positions
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	std::array pos = {
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		vec2(     0.0f, dstStartYF),
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		vec2(dstWidthF, dstStartYF),
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		vec2(dstWidthF, dstEndYF  ),
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		vec2(     0.0f, dstEndYF  ),
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	};
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	// texture coordinates, X-coord shared, Y-coord separate for tex0 and tex1
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	float tex0StartY = (srcStartYF + vShift) / srcHeightF;
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	float tex0EndY   = (srcEndYF   + vShift) / srcHeightF;
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	float tex1StartY = (srcStartYF + vShift) / logSrcHeightF;
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	float tex1EndY   = (srcEndYF   + vShift) / logSrcHeightF;
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	std::array tex = {
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		vec3(0.0f + hShift, tex0StartY, tex1StartY),
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		vec3(1.0f + hShift, tex0StartY, tex1StartY),
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		vec3(1.0f + hShift, tex0EndY  , tex1EndY  ),
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		vec3(0.0f + hShift, tex0EndY  , tex1EndY  ),
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	};
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	glBindBuffer(GL_ARRAY_BUFFER, vbo[0].get());
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	glBufferData(GL_ARRAY_BUFFER, sizeof(pos), pos.data(), GL_STREAM_DRAW);
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	glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
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	glBindBuffer(GL_ARRAY_BUFFER, vbo[1].get());
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	glBufferData(GL_ARRAY_BUFFER, sizeof(tex), tex.data(), GL_STREAM_DRAW);
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	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, 0, nullptr);
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	glEnableVertexAttribArray(0);
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	glEnableVertexAttribArray(1);
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	glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
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	glDisableVertexAttribArray(1);
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	glDisableVertexAttribArray(0);
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	glBindBuffer(GL_ARRAY_BUFFER, 0);
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}
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} // namespace openmsx