PostProcessor.cc

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#include "PostProcessor.hh"
 
#include "AviRecorder.hh"
#include "CliComm.hh"
#include "CommandException.hh"
#include "Deflicker.hh"
#include "DeinterlacedFrame.hh"
#include "Display.hh"
#include "DoubledFrame.hh"
#include "Event.hh"
#include "EventDistributor.hh"
#include "FloatSetting.hh"
#include "GLContext.hh"
#include "GLScaler.hh"
#include "GLScalerFactory.hh"
#include "MSXMotherBoard.hh"
#include "OutputSurface.hh"
#include "PNG.hh"
#include "RawFrame.hh"
#include "Reactor.hh"
#include "RenderSettings.hh"
#include "SuperImposedFrame.hh"
#include "gl_transform.hh"
 
#include "MemBuffer.hh"
#include "aligned.hh"
#include "narrow.hh"
#include "random.hh"
#include "ranges.hh"
#include "stl.hh"
#include "vla.hh"
#include "xrange.hh"
 
#include <algorithm>
#include <cassert>
#include <cstdint>
#include <memory>
#include <numeric>
 
using namespace gl;
 
namespace openmsx {
 
PostProcessor::PostProcessor(
        MSXMotherBoard& motherBoard_, Display& display_,
        OutputSurface& screen_, const std::string& videoSource,
        unsigned maxWidth_, unsigned height_, bool canDoInterlace_)
        : VideoLayer(motherBoard_, videoSource)
        , Schedulable(motherBoard_.getScheduler())
        , display(display_)
        , renderSettings(display_.getRenderSettings())
        , eventDistributor(motherBoard_.getReactor().getEventDistributor())
        , screen(screen_)
        , maxWidth(maxWidth_)
        , height(height_)
        , canDoInterlace(canDoInterlace_)
        , lastRotate(motherBoard_.getCurrentTime())
{
        if (canDoInterlace) {
                deinterlacedFrame = std::make_unique<DeinterlacedFrame>();
                interlacedFrame   = std::make_unique<DoubledFrame>();
                deflicker = std::make_unique<Deflicker>(lastFrames);
                superImposedFrame = std::make_unique<SuperImposedFrame>();
        } else {
                // Laserdisc always produces non-interlaced frames, so we don't
                // need lastFrames[1..3], deinterlacedFrame and
                // interlacedFrame. Also it produces a complete frame at a
                // time, so we don't need lastFrames[0] (and have a separate
                // work buffer, for partially rendered frames).
        }
 
        preCalcNoise(renderSettings.getNoise());
        initBuffers();
 
        VertexShader   vertexShader  ("monitor3D.vert");
        FragmentShader fragmentShader("monitor3D.frag");
        monitor3DProg.attach(vertexShader);
        monitor3DProg.attach(fragmentShader);
        monitor3DProg.bindAttribLocation(0, "a_position");
        monitor3DProg.bindAttribLocation(1, "a_normal");
        monitor3DProg.bindAttribLocation(2, "a_texCoord");
        monitor3DProg.link();
        preCalcMonitor3D(renderSettings.getHorizontalStretch());
 
        renderSettings.getNoiseSetting().attach(*this);
        renderSettings.getHorizontalStretchSetting().attach(*this);
}
 
PostProcessor::~PostProcessor()
{
        renderSettings.getHorizontalStretchSetting().detach(*this);
        renderSettings.getNoiseSetting().detach(*this);
 
        if (recorder) {
                getCliComm().printWarning(
                        "Video recording stopped, because you "
                        "changed machine or changed a video setting "
                        "during recording.");
                recorder->stop();
        }
}
 
void PostProcessor::initBuffers()
{
        // combined positions and texture coordinates
        static constexpr std::array pos_tex = {
                vec2(-1, 1), vec2(-1,-1), vec2( 1,-1), vec2( 1, 1), // pos
                vec2( 0, 1), vec2( 0, 0), vec2( 1, 0), vec2( 1, 1), // tex
        };
        glBindBuffer(GL_ARRAY_BUFFER, vbo.get());
        glBufferData(GL_ARRAY_BUFFER, sizeof(pos_tex), pos_tex.data(), GL_STATIC_DRAW);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
}
 
CliComm& PostProcessor::getCliComm()
{
        return display.getCliComm();
}
 
unsigned PostProcessor::getLineWidth(
        FrameSource* frame, unsigned y, unsigned step)
{
        return max_value(xrange(step), [&](auto i) { return frame->getLineWidth(y + i); });
}
 
void PostProcessor::executeUntil(EmuTime::param /*time*/)
{
        // insert fake end of frame event
        eventDistributor.distributeEvent(FinishFrameEvent(
                getVideoSource(), getVideoSourceSetting(), false));
}
 
using WorkBuffer = std::vector<MemBuffer<FrameSource::Pixel, SSE_ALIGNMENT>>;
static void getScaledFrame(const FrameSource& paintFrame,
                           std::span<const FrameSource::Pixel*> lines,
                           WorkBuffer& workBuffer)
{
        auto height = narrow<unsigned>(lines.size());
        unsigned width = (height == 240) ? 320 : 640;
        const FrameSource::Pixel* linePtr = nullptr;
        FrameSource::Pixel* work = nullptr;
        for (auto i : xrange(height)) {
                if (linePtr == work) {
                        // If work buffer was used in previous iteration,
                        // then allocate a new one.
                        work = workBuffer.emplace_back(width).data();
                }
                if (height == 240) {
                        auto line = paintFrame.getLinePtr320_240(i, std::span<uint32_t, 320>{work, 320});
                        linePtr = line.data();
                } else {
                        assert (height == 480);
                        auto line = paintFrame.getLinePtr640_480(i, std::span<uint32_t, 640>{work, 640});
                        linePtr = line.data();
                }
                lines[i] = linePtr;
        }
}
 
void PostProcessor::takeRawScreenShot(unsigned height2, const std::string& filename)
{
        if (!paintFrame) {
                throw CommandException("TODO");
        }
 
        VLA(const FrameSource::Pixel*, lines, height2);
        WorkBuffer workBuffer;
        getScaledFrame(*paintFrame, lines, workBuffer);
        unsigned width = (height2 == 240) ? 320 : 640;
        PNG::saveRGBA(width, lines, filename);
}
 
void PostProcessor::createRegions()
{
        regions.clear();
 
        const unsigned srcHeight = paintFrame->getHeight();
        const unsigned dstHeight = screen.getLogicalHeight();
 
        unsigned g = std::gcd(srcHeight, dstHeight);
        unsigned srcStep = srcHeight / g;
        unsigned dstStep = dstHeight / g;
 
        // TODO: Store all MSX lines in RawFrame and only scale the ones that fit
        //       on the PC screen, as a preparation for resizable output window.
        unsigned srcStartY = 0;
        unsigned dstStartY = 0;
        while (dstStartY < dstHeight) {
                // Currently this is true because the source frame height
                // is always >= dstHeight/(dstStep/srcStep).
                assert(srcStartY < srcHeight);
 
                // get region with equal lineWidth
                unsigned lineWidth = getLineWidth(paintFrame, srcStartY, srcStep);
                unsigned srcEndY = srcStartY + srcStep;
                unsigned dstEndY = dstStartY + dstStep;
                while ((srcEndY < srcHeight) && (dstEndY < dstHeight) &&
                       (getLineWidth(paintFrame, srcEndY, srcStep) == lineWidth)) {
                        srcEndY += srcStep;
                        dstEndY += dstStep;
                }
 
                regions.emplace_back(srcStartY, srcEndY,
                                     dstStartY, dstEndY,
                                     lineWidth);
 
                // next region
                srcStartY = srcEndY;
                dstStartY = dstEndY;
        }
}
 
void PostProcessor::paint(OutputSurface& /*output*/)
{
        if (renderSettings.getInterleaveBlackFrame()) {
                interleaveCount ^= 1;
                if (interleaveCount) {
                        glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
                        glClear(GL_COLOR_BUFFER_BIT);
                        return;
                }
        }
 
        auto deform = renderSettings.getDisplayDeform();
        float horStretch = renderSettings.getHorizontalStretch();
        int glow = renderSettings.getGlow();
 
        if ((screen.getViewOffset() != ivec2()) || // any part of the screen not covered by the viewport?
            (deform == RenderSettings::DisplayDeform::_3D) || !paintFrame) {
                glClearColor(0.0f, 0.0f, 0.0f, 1.0f);
                glClear(GL_COLOR_BUFFER_BIT);
                if (!paintFrame) {
                        return;
                }
        }
 
        // New scaler algorithm selected?
        if (auto algo = renderSettings.getScaleAlgorithm();
            scaleAlgorithm != algo) {
                scaleAlgorithm = algo;
                currScaler = GLScalerFactory::createScaler(renderSettings);
 
                // Re-upload frame data, this is both
                //  - Chunks of RawFrame with a specific line width, possibly
                //    with some extra lines above and below each chunk that are
                //    also converted to this line width.
                //  - Extra data that is specific for the scaler (ATM only the
                //    hq and hqlite scalers require this).
                // Re-uploading the first is not strictly needed. But switching
                // scalers doesn't happen that often, so it also doesn't hurt
                // and it keeps the code simpler.
                uploadFrame();
        }
 
        auto size = screen.getLogicalSize();
        glViewport(0, 0, size.x, size.y);
        glBindTexture(GL_TEXTURE_2D, 0);
        auto& renderedFrame = renderedFrames[frameCounter & 1];
        if (renderedFrame.size != size) {
                renderedFrame.tex.bind();
                renderedFrame.tex.setInterpolation(true);
                glTexImage2D(GL_TEXTURE_2D,     // target
                             0,                 // level
                             GL_RGB,            // internal format
                             size.x,            // width
                             size.y,            // height
                             0,                 // border
                             GL_RGB,            // format
                             GL_UNSIGNED_BYTE,  // type
                             nullptr);          // data
                renderedFrame.fbo = FrameBufferObject(renderedFrame.tex);
        }
        renderedFrame.fbo.push();
 
        for (const auto& r : regions) {
                auto it = find_unguarded(textures, r.lineWidth, &TextureData::width);
                auto* superImpose = superImposeVideoFrame
                                  ? &superImposeTex : nullptr;
                currScaler->scaleImage(
                        it->tex, superImpose,
                        r.srcStartY, r.srcEndY, r.lineWidth, // src
                        r.dstStartY, r.dstEndY, size.x,   // dst
                        paintFrame->getHeight()); // dst
        }
 
        drawNoise();
        drawGlow(glow);
 
        renderedFrame.fbo.pop();
        renderedFrame.tex.bind();
        auto [x, y] = screen.getViewOffset();
        auto [w, h] = screen.getViewSize();
        glViewport(x, y, w, h);
 
        if (deform == RenderSettings::DisplayDeform::_3D) {
                drawMonitor3D();
        } else {
                float x1 = (320.0f - float(horStretch)) * (1.0f / (2.0f * 320.0f));
                float x2 = 1.0f - x1;
                std::array tex = {
                        vec2(x1, 1), vec2(x1, 0), vec2(x2, 0), vec2(x2, 1)
                };
 
                const auto& glContext = *gl::context;
                glContext.progTex.activate();
                glUniform4f(glContext.unifTexColor,
                                1.0f, 1.0f, 1.0f, 1.0f);
                mat4 I;
                glUniformMatrix4fv(glContext.unifTexMvp, 1, GL_FALSE, I.data());
 
                glBindBuffer(GL_ARRAY_BUFFER, vbo.get());
                glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
                glEnableVertexAttribArray(0);
 
                glBindBuffer(GL_ARRAY_BUFFER, stretchVBO.get());
                glBufferData(GL_ARRAY_BUFFER, sizeof(tex), tex.data(), GL_STREAM_DRAW);
                glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, nullptr);
                glEnableVertexAttribArray(1);
 
                glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 
                glDisableVertexAttribArray(1);
                glDisableVertexAttribArray(0);
                glBindBuffer(GL_ARRAY_BUFFER, 0);
        }
        storedFrame = true;
        //gl::checkGLError("PostProcessor::paint");
}
 
std::unique_ptr<RawFrame> PostProcessor::rotateFrames(
        std::unique_ptr<RawFrame> finishedFrame, EmuTime::param time)
{
        if (renderSettings.getInterleaveBlackFrame()) {
                auto delta = time - lastRotate; // time between last two calls
                auto middle = time + delta / 2; // estimate for middle between now
                                                // and next call
                setSyncPoint(middle);
        }
        lastRotate = time;
 
        // Figure out how many past frames we want to use.
        int numRequired = 1;
        bool doDeinterlace = false;
        bool doInterlace   = false;
        bool doDeflicker   = false;
        auto currType = finishedFrame->getField();
        if (canDoInterlace) {
                if (currType != FrameSource::FieldType::NONINTERLACED) {
                        if (renderSettings.getDeinterlace()) {
                                doDeinterlace = true;
                                numRequired = 2;
                        } else {
                                doInterlace = true;
                        }
                } else if (renderSettings.getDeflicker()) {
                        doDeflicker = true;
                        numRequired = 4;
                }
        }
 
        // Which frame can be returned (recycled) to caller. Prefer to return
        // the youngest frame to improve cache locality.
        int recycleIdx = (lastFramesCount < numRequired)
                ? lastFramesCount++  // store one more
                : (numRequired - 1); // youngest that's no longer needed
        assert(recycleIdx < 4);
        auto recycleFrame = std::move(lastFrames[recycleIdx]); // might be nullptr
 
        // Insert new frame in front of lastFrames[], shift older frames
        std::move_backward(&lastFrames[0], &lastFrames[recycleIdx],
                           &lastFrames[recycleIdx + 1]);
        lastFrames[0] = std::move(finishedFrame);
 
        // Are enough frames available?
        if (lastFramesCount >= numRequired) {
                // Only the last 'numRequired' are kept up to date.
                lastFramesCount = numRequired;
        } else {
                // Not enough past frames, fall back to 'regular' rendering.
                // This situation can only occur when:
                // - The very first frame we render needs to be deinterlaced.
                //   In other case we have at least one valid frame from the
                //   past plus one new frame passed via the 'finishedFrame'
                //   parameter.
                // - Or when (re)enabling the deflicker setting. Typically only
                //   1 frame in lastFrames[] is kept up-to-date (and we're
                //   given 1 new frame), so it can take up-to 2 frame after
                //   enabling deflicker before it actually takes effect.
                doDeinterlace = false;
                doInterlace   = false;
                doDeflicker   = false;
        }
 
        // Setup the to-be-painted frame
        if (doDeinterlace) {
                if (currType == FrameSource::FieldType::ODD) {
                        deinterlacedFrame->init(lastFrames[1].get(), lastFrames[0].get());
                } else {
                        deinterlacedFrame->init(lastFrames[0].get(), lastFrames[1].get());
                }
                paintFrame = deinterlacedFrame.get();
        } else if (doInterlace) {
                interlacedFrame->init(
                        lastFrames[0].get(),
                        (currType == FrameSource::FieldType::ODD) ? 1 : 0);
                paintFrame = interlacedFrame.get();
        } else if (doDeflicker) {
                deflicker->init();
                paintFrame = deflicker.get();
        } else {
                paintFrame = lastFrames[0].get();
        }
        if (superImposeVdpFrame) {
                superImposedFrame->init(paintFrame, superImposeVdpFrame);
                paintFrame = superImposedFrame.get();
        }
 
        // Possibly record this frame
        if (recorder && needRecord()) {
                try {
                        recorder->addImage(paintFrame, time);
                } catch (MSXException& e) {
                        getCliComm().printWarning(
                                "Recording stopped with error: ",
                                e.getMessage());
                        recorder->stop();
                        assert(!recorder);
                }
        }
 
        // Return recycled frame to the caller
        std::unique_ptr<RawFrame> reuseFrame = [&] {
                if (canDoInterlace) {
                        if (!recycleFrame) [[unlikely]] {
                                recycleFrame = std::make_unique<RawFrame>(maxWidth, height);
                        }
                        return std::move(recycleFrame);
                } else {
                        return std::move(lastFrames[0]);
                }
        }();
 
        uploadFrame();
        ++frameCounter;
        noiseX = random_float(0.0f, 1.0f);
        noiseY = random_float(0.0f, 1.0f);
        return reuseFrame;
}
 
void PostProcessor::update(const Setting& setting) noexcept
{
        VideoLayer::update(setting);
        const auto& noiseSetting = renderSettings.getNoiseSetting();
        const auto& horizontalStretch = renderSettings.getHorizontalStretchSetting();
        if (&setting == &noiseSetting) {
                preCalcNoise(noiseSetting.getFloat());
        } else if (&setting == &horizontalStretch) {
                preCalcMonitor3D(horizontalStretch.getFloat());
        }
}
 
void PostProcessor::uploadFrame()
{
        createRegions();
 
        const unsigned srcHeight = paintFrame->getHeight();
        for (const auto& r : regions) {
                // upload data
                // TODO get before/after data from scaler
                int before = 1;
                unsigned after  = 1;
                uploadBlock(narrow<unsigned>(std::max(0, narrow<int>(r.srcStartY) - before)),
                            std::min(srcHeight, r.srcEndY + after),
                            r.lineWidth);
        }
 
        if (superImposeVideoFrame) {
                int w = narrow<GLsizei>(superImposeVideoFrame->getWidth());
                int h = narrow<GLsizei>(superImposeVideoFrame->getHeight());
                if (superImposeTex.getWidth()  != w ||
                    superImposeTex.getHeight() != h) {
                        superImposeTex.resize(w, h);
                        superImposeTex.setInterpolation(true);
                }
                superImposeTex.bind();
                glTexSubImage2D(
                        GL_TEXTURE_2D,     // target
                        0,                 // level
                        0,                 // offset x
                        0,                 // offset y
                        w,                 // width
                        h,                 // height
                        GL_RGBA,           // format
                        GL_UNSIGNED_BYTE,  // type
                        const_cast<RawFrame*>(superImposeVideoFrame)->getLineDirect(0).data()); // data
        }
}
 
void PostProcessor::uploadBlock(
        unsigned srcStartY, unsigned srcEndY, unsigned lineWidth)
{
        // create texture/pbo if needed
        auto it = ranges::find(textures, lineWidth, &TextureData::width);
        if (it == end(textures)) {
                TextureData textureData;
 
                textureData.tex.resize(narrow<GLsizei>(lineWidth),
                                       narrow<GLsizei>(height * 2)); // *2 for interlace
                textureData.pbo.setImage(lineWidth, height * 2);
                textures.push_back(std::move(textureData));
                it = end(textures) - 1;
        }
        auto& tex = it->tex;
        auto& pbo = it->pbo;
 
        // bind texture
        tex.bind();
 
        // upload data
        pbo.bind();
        uint32_t* mapped = pbo.mapWrite();
        for (auto y : xrange(srcStartY, srcEndY)) {
                auto* dest = mapped + y * size_t(lineWidth);
                auto line = paintFrame->getLine(narrow<int>(y), std::span{dest, lineWidth});
                if (line.data() != dest) {
                        ranges::copy(line, dest);
                }
        }
        pbo.unmap();
#if defined(__APPLE__)
        // The nVidia GL driver for the GeForce 8000/9000 series seems to hang
        // on texture data replacements that are 1 pixel wide and start on a
        // line number that is a non-zero multiple of 16.
        if (lineWidth == 1 && srcStartY != 0 && srcStartY % 16 == 0) {
                srcStartY--;
        }
#endif
        glTexSubImage2D(
                GL_TEXTURE_2D,                      // target
                0,                                  // level
                0,                                  // offset x
                narrow<GLint>(srcStartY),           // offset y
                narrow<GLint>(lineWidth),           // width
                narrow<GLint>(srcEndY - srcStartY), // height
                GL_RGBA,                            // format
                GL_UNSIGNED_BYTE,                   // type
                pbo.getOffset(0, srcStartY));       // data
        pbo.unbind();
 
        // possibly upload scaler specific data
        if (currScaler) {
                currScaler->uploadBlock(srcStartY, srcEndY, lineWidth, *paintFrame);
        }
}
 
void PostProcessor::drawGlow(int glow)
{
        if ((glow == 0) || !storedFrame) return;
 
        const auto& glContext = *gl::context;
        glContext.progTex.activate();
        glEnable(GL_BLEND);
        glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
        renderedFrames[(frameCounter & 1) ^ 1].tex.bind();
        glUniform4f(glContext.unifTexColor,
                    1.0f, 1.0f, 1.0f, narrow<float>(glow) * (31.0f / 3200.0f));
        mat4 I;
        glUniformMatrix4fv(glContext.unifTexMvp, 1, GL_FALSE, I.data());
 
        glBindBuffer(GL_ARRAY_BUFFER, vbo.get());
 
        const vec2* offset = nullptr;
        glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, offset); // pos
        offset += 4; // see initBuffers()
        glEnableVertexAttribArray(0);
 
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, offset); // tex
        glEnableVertexAttribArray(1);
 
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 
        glDisableVertexAttribArray(1);
        glDisableVertexAttribArray(0);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glDisable(GL_BLEND);
}
 
void PostProcessor::preCalcNoise(float factor)
{
        std::array<uint8_t, 256 * 256> buf1;
        std::array<uint8_t, 256 * 256> buf2;
        auto& generator = global_urng(); // fast (non-cryptographic) random numbers
        std::normal_distribution<float> distribution(0.0f, 1.0f);
        for (auto i : xrange(256 * 256)) {
                float r = distribution(generator);
                int s = std::clamp(int(roundf(r * factor)), -255, 255);
                buf1[i] = narrow<uint8_t>((s > 0) ?  s : 0);
                buf2[i] = narrow<uint8_t>((s < 0) ? -s : 0);
        }
 
        // GL_LUMINANCE is no longer supported in newer openGL versions
        auto format = (OPENGL_VERSION >= OPENGL_3_3) ? GL_RED : GL_LUMINANCE;
        noiseTextureA.bind();
        glTexImage2D(
                GL_TEXTURE_2D,    // target
                0,                // level
                format,           // internal format
                256,              // width
                256,              // height
                0,                // border
                format,           // format
                GL_UNSIGNED_BYTE, // type
                buf1.data());     // data
#if OPENGL_VERSION >= OPENGL_3_3
        GLint swizzleMask1[] = {GL_RED, GL_RED, GL_RED, GL_ONE};
        glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_RGBA, swizzleMask1);
#endif
 
        noiseTextureB.bind();
        glTexImage2D(
                GL_TEXTURE_2D,    // target
                0,                // level
                format,           // internal format
                256,              // width
                256,              // height
                0,                // border
                format,           // format
                GL_UNSIGNED_BYTE, // type
                buf2.data());     // data
#if OPENGL_VERSION >= OPENGL_3_3
        GLint swizzleMask2[] = {GL_RED, GL_RED, GL_RED, GL_ONE};
        glTexParameteriv(GL_TEXTURE_2D, GL_TEXTURE_SWIZZLE_RGBA, swizzleMask2);
#endif
}
 
void PostProcessor::drawNoise() const
{
        if (renderSettings.getNoise() == 0.0f) return;
 
        // Rotate and mirror noise texture in consecutive frames to avoid
        // seeing 'patterns' in the noise.
        static constexpr std::array pos = {
                std::array{vec2{-1, -1}, vec2{ 1, -1}, vec2{ 1,  1}, vec2{-1,  1}},
                std::array{vec2{-1,  1}, vec2{ 1,  1}, vec2{ 1, -1}, vec2{-1, -1}},
                std::array{vec2{-1,  1}, vec2{-1, -1}, vec2{ 1, -1}, vec2{ 1,  1}},
                std::array{vec2{ 1,  1}, vec2{ 1, -1}, vec2{-1, -1}, vec2{-1,  1}},
                std::array{vec2{ 1,  1}, vec2{-1,  1}, vec2{-1, -1}, vec2{ 1, -1}},
                std::array{vec2{ 1, -1}, vec2{-1, -1}, vec2{-1,  1}, vec2{ 1,  1}},
                std::array{vec2{ 1, -1}, vec2{ 1,  1}, vec2{-1,  1}, vec2{-1, -1}},
                std::array{vec2{-1, -1}, vec2{-1,  1}, vec2{ 1,  1}, vec2{ 1, -1}},
        };
        vec2 noise(noiseX, noiseY);
        const std::array tex = {
                noise + vec2(0.0f, 1.875f),
                noise + vec2(2.0f, 1.875f),
                noise + vec2(2.0f, 0.0f  ),
                noise + vec2(0.0f, 0.0f  ),
        };
 
        const auto& glContext = *gl::context;
        glContext.progTex.activate();
 
        glEnable(GL_BLEND);
        glBlendFunc(GL_ONE, GL_ONE);
        glUniform4f(glContext.unifTexColor, 1.0f, 1.0f, 1.0f, 1.0f);
        mat4 I;
        glUniformMatrix4fv(glContext.unifTexMvp, 1, GL_FALSE, I.data());
 
        unsigned seq = frameCounter & 7;
        glVertexAttribPointer(0, 2, GL_FLOAT, GL_FALSE, 0, pos[seq].data());
        glVertexAttribPointer(1, 2, GL_FLOAT, GL_FALSE, 0, tex.data());
        glEnableVertexAttribArray(0);
        glEnableVertexAttribArray(1);
 
        noiseTextureA.bind();
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
        glBlendEquation(GL_FUNC_REVERSE_SUBTRACT);
        noiseTextureB.bind();
        glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
 
        glDisableVertexAttribArray(1);
        glDisableVertexAttribArray(0);
        glBlendEquation(GL_FUNC_ADD); // restore default
        glDisable(GL_BLEND);
}
 
static constexpr int GRID_SIZE = 16;
static constexpr int GRID_SIZE1 = GRID_SIZE + 1;
static constexpr int NUM_INDICES = (GRID_SIZE1 * 2 + 2) * GRID_SIZE - 2;
struct Vertex {
        vec3 position;
        vec3 normal;
        vec2 tex;
};
 
void PostProcessor::preCalcMonitor3D(float width)
{
        // precalculate vertex-positions, -normals and -texture-coordinates
        std::array<std::array<Vertex, GRID_SIZE1>, GRID_SIZE1> vertices;
 
        constexpr float GRID_SIZE2 = float(GRID_SIZE) * 0.5f;
        float s = width * (1.0f / 320.0f);
        float b = (320.0f - width) * (1.0f / (2.0f * 320.0f));
 
        for (auto sx : xrange(GRID_SIZE1)) {
                for (auto sy : xrange(GRID_SIZE1)) {
                        Vertex& v = vertices[sx][sy];
                        float x = (narrow<float>(sx) - GRID_SIZE2) / GRID_SIZE2;
                        float y = (narrow<float>(sy) - GRID_SIZE2) / GRID_SIZE2;
 
                        v.position = vec3(x, y, (x * x + y * y) * (1.0f / -12.0f));
                        v.normal = normalize(vec3(x * (1.0f / 6.0f), y * (1.0f / 6.0f), 1.0f)) * 1.2f;
                        v.tex = vec2((float(sx) / GRID_SIZE) * s + b,
                                      float(sy) / GRID_SIZE);
                }
        }
 
        // calculate indices
        std::array<uint16_t, NUM_INDICES> indices;
 
        uint16_t* ind = indices.data();
        for (auto y : xrange(GRID_SIZE)) {
                for (auto x : xrange(GRID_SIZE1)) {
                        *ind++ = narrow<uint16_t>((y + 0) * GRID_SIZE1 + x);
                        *ind++ = narrow<uint16_t>((y + 1) * GRID_SIZE1 + x);
                }
                // skip 2, filled in later
                ind += 2;
        }
        assert((ind - indices.data()) == NUM_INDICES + 2);
        ind = indices.data();
        repeat(GRID_SIZE - 1, [&] {
                ind += 2 * GRID_SIZE1;
                // repeat prev and next index to restart strip
                ind[0] = ind[-1];
                ind[1] = ind[ 2];
                ind += 2;
        });
 
        // upload calculated values to buffers
        glBindBuffer(GL_ARRAY_BUFFER, arrayBuffer.get());
        glBufferData(GL_ARRAY_BUFFER, sizeof(vertices), vertices.data(),
                     GL_STATIC_DRAW);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementBuffer.get());
        glBufferData(GL_ELEMENT_ARRAY_BUFFER, sizeof(indices), indices.data(),
                     GL_STATIC_DRAW);
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
 
        // calculate transformation matrices
        mat4 proj = frustum(-1, 1, -1, 1, 1, 10);
        mat4 tran = translate(vec3(0.0f, 0.4f, -2.0f));
        mat4 rotX = rotateX(radians(-10.0f));
        mat4 scal = scale(vec3(2.2f, 2.2f, 2.2f));
 
        mat3 normal(rotX);
        mat4 mvp = proj * tran * rotX * scal;
 
        // set uniforms
        monitor3DProg.activate();
        glUniform1i(monitor3DProg.getUniformLocation("u_tex"), 0);
        glUniformMatrix4fv(monitor3DProg.getUniformLocation("u_mvpMatrix"),
                1, GL_FALSE, mvp.data());
        glUniformMatrix3fv(monitor3DProg.getUniformLocation("u_normalMatrix"),
                1, GL_FALSE, normal.data());
}
 
void PostProcessor::drawMonitor3D() const
{
        monitor3DProg.activate();
 
        char* base = nullptr;
        glBindBuffer(GL_ARRAY_BUFFER, arrayBuffer.get());
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, elementBuffer.get());
        glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
                              base);
        glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex),
                              base + sizeof(vec3));
        glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex),
                              base + sizeof(vec3) + sizeof(vec3));
        glEnableVertexAttribArray(0);
        glEnableVertexAttribArray(1);
        glEnableVertexAttribArray(2);
 
        glDrawElements(GL_TRIANGLE_STRIP, NUM_INDICES, GL_UNSIGNED_SHORT, nullptr);
        glDisableVertexAttribArray(2);
        glDisableVertexAttribArray(1);
        glDisableVertexAttribArray(0);
 
        glBindBuffer(GL_ARRAY_BUFFER, 0);
        glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
}
 
} // namespace openmsx