src/libANGLE/renderer/gl/RendererGL.cpp

//
// Copyright 2015 The ANGLE Project Authors. All rights reserved.
// Use of this source code is governed by a BSD-style license that can be
// found in the LICENSE file.
//

// RendererGL.cpp: Implements the class methods for RendererGL.

#include "libANGLE/renderer/gl/RendererGL.h"

#include <EGL/eglext.h>

#include "common/debug.h"
#include "libANGLE/AttributeMap.h"
#include "libANGLE/Context.h"
#include "libANGLE/ContextState.h"
#include "libANGLE/Path.h"
#include "libANGLE/Surface.h"
#include "libANGLE/renderer/gl/BlitGL.h"
#include "libANGLE/renderer/gl/BufferGL.h"
#include "libANGLE/renderer/gl/ClearMultiviewGL.h"
#include "libANGLE/renderer/gl/CompilerGL.h"
#include "libANGLE/renderer/gl/ContextGL.h"
#include "libANGLE/renderer/gl/FenceNVGL.h"
#include "libANGLE/renderer/gl/FramebufferGL.h"
#include "libANGLE/renderer/gl/FunctionsGL.h"
#include "libANGLE/renderer/gl/PathGL.h"
#include "libANGLE/renderer/gl/ProgramGL.h"
#include "libANGLE/renderer/gl/QueryGL.h"
#include "libANGLE/renderer/gl/RenderbufferGL.h"
#include "libANGLE/renderer/gl/SamplerGL.h"
#include "libANGLE/renderer/gl/ShaderGL.h"
#include "libANGLE/renderer/gl/StateManagerGL.h"
#include "libANGLE/renderer/gl/SurfaceGL.h"
#include "libANGLE/renderer/gl/SyncGL.h"
#include "libANGLE/renderer/gl/TextureGL.h"
#include "libANGLE/renderer/gl/TransformFeedbackGL.h"
#include "libANGLE/renderer/gl/VertexArrayGL.h"
#include "libANGLE/renderer/gl/renderergl_utils.h"
#include "libANGLE/renderer/renderer_utils.h"

namespace
{

std::vector<GLuint> GatherPaths(const std::vector<gl::Path *> &paths)
{
    std::vector<GLuint> ret;
    ret.reserve(paths.size());

    for (const auto *p : paths)
    {
        const auto *pathObj = rx::GetImplAs<rx::PathGL>(p);
        ret.push_back(pathObj->getPathID());
    }
    return ret;
}

}  // namespace

static void INTERNAL_GL_APIENTRY LogGLDebugMessage(GLenum source,
                                                   GLenum type,
                                                   GLuint id,
                                                   GLenum severity,
                                                   GLsizei length,
                                                   const GLchar *message,
                                                   const void *userParam)
{
    std::string sourceText;
    switch (source)
    {
        case GL_DEBUG_SOURCE_API:
            sourceText = "OpenGL";
            break;
        case GL_DEBUG_SOURCE_WINDOW_SYSTEM:
            sourceText = "Windows";
            break;
        case GL_DEBUG_SOURCE_SHADER_COMPILER:
            sourceText = "Shader Compiler";
            break;
        case GL_DEBUG_SOURCE_THIRD_PARTY:
            sourceText = "Third Party";
            break;
        case GL_DEBUG_SOURCE_APPLICATION:
            sourceText = "Application";
            break;
        case GL_DEBUG_SOURCE_OTHER:
            sourceText = "Other";
            break;
        default:
            sourceText = "UNKNOWN";
            break;
    }

    std::string typeText;
    switch (type)
    {
        case GL_DEBUG_TYPE_ERROR:
            typeText = "Error";
            break;
        case GL_DEBUG_TYPE_DEPRECATED_BEHAVIOR:
            typeText = "Deprecated behavior";
            break;
        case GL_DEBUG_TYPE_UNDEFINED_BEHAVIOR:
            typeText = "Undefined behavior";
            break;
        case GL_DEBUG_TYPE_PORTABILITY:
            typeText = "Portability";
            break;
        case GL_DEBUG_TYPE_PERFORMANCE:
            typeText = "Performance";
            break;
        case GL_DEBUG_TYPE_OTHER:
            typeText = "Other";
            break;
        case GL_DEBUG_TYPE_MARKER:
            typeText = "Marker";
            break;
        default:
            typeText = "UNKNOWN";
            break;
    }

    std::string severityText;
    switch (severity)
    {
        case GL_DEBUG_SEVERITY_HIGH:
            severityText = "High";
            break;
        case GL_DEBUG_SEVERITY_MEDIUM:
            severityText = "Medium";
            break;
        case GL_DEBUG_SEVERITY_LOW:
            severityText = "Low";
            break;
        case GL_DEBUG_SEVERITY_NOTIFICATION:
            severityText = "Notification";
            break;
        default:
            severityText = "UNKNOWN";
            break;
    }

    if (type == GL_DEBUG_TYPE_ERROR)
    {
        ERR() << std::endl
              << "\tSource: " << sourceText << std::endl
              << "\tType: " << typeText << std::endl
              << "\tID: " << gl::Error(id) << std::endl
              << "\tSeverity: " << severityText << std::endl
              << "\tMessage: " << message;
    }
    else if (type != GL_DEBUG_TYPE_PERFORMANCE)
    {
        // Don't print performance warnings. They tend to be very spammy in the dEQP test suite and
        // there is very little we can do about them.

        // TODO(ynovikov): filter into WARN and INFO if INFO is ever implemented
        WARN() << std::endl
               << "\tSource: " << sourceText << std::endl
               << "\tType: " << typeText << std::endl
               << "\tID: " << gl::Error(id) << std::endl
               << "\tSeverity: " << severityText << std::endl
               << "\tMessage: " << message;
    }
}

namespace rx
{

RendererGL::RendererGL(std::unique_ptr<FunctionsGL> functions, const egl::AttributeMap &attribMap)
    : mMaxSupportedESVersion(0, 0),
      mFunctions(std::move(functions)),
      mStateManager(nullptr),
      mBlitter(nullptr),
      mMultiviewClearer(nullptr),
      mUseDebugOutput(false),
      mCapsInitialized(false),
      mMultiviewImplementationType(MultiviewImplementationTypeGL::UNSPECIFIED)
{
    ASSERT(mFunctions);
    nativegl_gl::GenerateWorkarounds(mFunctions.get(), &mWorkarounds);
    mStateManager = new StateManagerGL(mFunctions.get(), getNativeCaps(), getNativeExtensions());
    mBlitter      = new BlitGL(mFunctions.get(), mWorkarounds, mStateManager);
    mMultiviewClearer = new ClearMultiviewGL(mFunctions.get(), mStateManager);

    bool hasDebugOutput = mFunctions->isAtLeastGL(gl::Version(4, 3)) ||
                          mFunctions->hasGLExtension("GL_KHR_debug") ||
                          mFunctions->isAtLeastGLES(gl::Version(3, 2)) ||
                          mFunctions->hasGLESExtension("GL_KHR_debug");

    mUseDebugOutput = hasDebugOutput && ShouldUseDebugLayers(attribMap);

    if (mUseDebugOutput)
    {
        mFunctions->enable(GL_DEBUG_OUTPUT);
        mFunctions->enable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
        mFunctions->debugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_HIGH, 0,
                                        nullptr, GL_TRUE);
        mFunctions->debugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_MEDIUM, 0,
                                        nullptr, GL_TRUE);
        mFunctions->debugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_LOW, 0,
                                        nullptr, GL_FALSE);
        mFunctions->debugMessageControl(GL_DONT_CARE, GL_DONT_CARE, GL_DEBUG_SEVERITY_NOTIFICATION,
                                        0, nullptr, GL_FALSE);
        mFunctions->debugMessageCallback(&LogGLDebugMessage, nullptr);
    }

    if (mWorkarounds.initializeCurrentVertexAttributes)
    {
        GLint maxVertexAttribs = 0;
        mFunctions->getIntegerv(GL_MAX_VERTEX_ATTRIBS, &maxVertexAttribs);

        for (GLint i = 0; i < maxVertexAttribs; ++i)
        {
            mFunctions->vertexAttrib4f(i, 0.0f, 0.0f, 0.0f, 1.0f);
        }
    }
}

RendererGL::~RendererGL()
{
    SafeDelete(mBlitter);
    SafeDelete(mMultiviewClearer);
    SafeDelete(mStateManager);
}

angle::Result RendererGL::flush()
{
    mFunctions->flush();
    return angle::Result::Continue();
}

angle::Result RendererGL::finish()
{
    if (mWorkarounds.finishDoesNotCauseQueriesToBeAvailable && mUseDebugOutput)
    {
        mFunctions->enable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
    }

    mFunctions->finish();

    if (mWorkarounds.finishDoesNotCauseQueriesToBeAvailable && mUseDebugOutput)
    {
        mFunctions->disable(GL_DEBUG_OUTPUT_SYNCHRONOUS);
    }

    return angle::Result::Continue();
}

angle::Result RendererGL::drawArrays(const gl::Context *context,
                                     gl::PrimitiveMode mode,
                                     GLint first,
                                     GLsizei count)
{
    const gl::Program *program  = context->getGLState().getProgram();
    const bool usesMultiview    = program->usesMultiview();
    const GLsizei instanceCount = usesMultiview ? program->getNumViews() : 0;

    ANGLE_TRY(mStateManager->setDrawArraysState(context, first, count, instanceCount));
    if (!usesMultiview)
    {
        mFunctions->drawArrays(ToGLenum(mode), first, count);
    }
    else
    {
        mFunctions->drawArraysInstanced(ToGLenum(mode), first, count, instanceCount);
    }
    return angle::Result::Continue();
}

angle::Result RendererGL::drawArraysInstanced(const gl::Context *context,
                                              gl::PrimitiveMode mode,
                                              GLint first,
                                              GLsizei count,
                                              GLsizei instanceCount)
{
    GLsizei adjustedInstanceCount = instanceCount;
    const gl::Program *program    = context->getGLState().getProgram();
    if (program->usesMultiview())
    {
        adjustedInstanceCount *= program->getNumViews();
    }

    ANGLE_TRY(mStateManager->setDrawArraysState(context, first, count, adjustedInstanceCount));
    mFunctions->drawArraysInstanced(ToGLenum(mode), first, count, adjustedInstanceCount);
    return angle::Result::Continue();
}

angle::Result RendererGL::drawElements(const gl::Context *context,
                                       gl::PrimitiveMode mode,
                                       GLsizei count,
                                       GLenum type,
                                       const void *indices)
{
    const gl::Program *program  = context->getGLState().getProgram();
    const bool usesMultiview    = program->usesMultiview();
    const GLsizei instanceCount = usesMultiview ? program->getNumViews() : 0;
    const void *drawIndexPtr    = nullptr;

    ANGLE_TRY(mStateManager->setDrawElementsState(context, count, type, indices, instanceCount,
                                                  &drawIndexPtr));
    if (!usesMultiview)
    {
        mFunctions->drawElements(ToGLenum(mode), count, type, drawIndexPtr);
    }
    else
    {
        mFunctions->drawElementsInstanced(ToGLenum(mode), count, type, drawIndexPtr, instanceCount);
    }
    return angle::Result::Continue();
}

angle::Result RendererGL::drawElementsInstanced(const gl::Context *context,
                                                gl::PrimitiveMode mode,
                                                GLsizei count,
                                                GLenum type,
                                                const void *indices,
                                                GLsizei instances)
{
    GLsizei adjustedInstanceCount = instances;
    const gl::Program *program    = context->getGLState().getProgram();
    if (program->usesMultiview())
    {
        adjustedInstanceCount *= program->getNumViews();
    }
    const void *drawIndexPointer = nullptr;

    ANGLE_TRY(mStateManager->setDrawElementsState(context, count, type, indices,
                                                  adjustedInstanceCount, &drawIndexPointer));
    mFunctions->drawElementsInstanced(ToGLenum(mode), count, type, drawIndexPointer,
                                      adjustedInstanceCount);
    return angle::Result::Continue();
}

angle::Result RendererGL::drawRangeElements(const gl::Context *context,
                                            gl::PrimitiveMode mode,
                                            GLuint start,
                                            GLuint end,
                                            GLsizei count,
                                            GLenum type,
                                            const void *indices)
{
    const gl::Program *program   = context->getGLState().getProgram();
    const bool usesMultiview     = program->usesMultiview();
    const GLsizei instanceCount  = usesMultiview ? program->getNumViews() : 0;
    const void *drawIndexPointer = nullptr;

    ANGLE_TRY(mStateManager->setDrawElementsState(context, count, type, indices, instanceCount,
                                                  &drawIndexPointer));
    if (!usesMultiview)
    {
        mFunctions->drawRangeElements(ToGLenum(mode), start, end, count, type, drawIndexPointer);
    }
    else
    {
        mFunctions->drawElementsInstanced(ToGLenum(mode), count, type, drawIndexPointer,
                                          instanceCount);
    }
    return angle::Result::Continue();
}

angle::Result RendererGL::drawArraysIndirect(const gl::Context *context,
                                             gl::PrimitiveMode mode,
                                             const void *indirect)
{
    ANGLE_TRY(mStateManager->setDrawIndirectState(context));
    mFunctions->drawArraysIndirect(ToGLenum(mode), indirect);
    return angle::Result::Continue();
}

angle::Result RendererGL::drawElementsIndirect(const gl::Context *context,
                                               gl::PrimitiveMode mode,
                                               GLenum type,
                                               const void *indirect)
{
    ANGLE_TRY(mStateManager->setDrawIndirectState(context));
    mFunctions->drawElementsIndirect(ToGLenum(mode), type, indirect);
    return angle::Result::Continue();
}

void RendererGL::stencilFillPath(const gl::ContextState &state,
                                 const gl::Path *path,
                                 GLenum fillMode,
                                 GLuint mask)
{
    const auto *pathObj = GetImplAs<PathGL>(path);

    mFunctions->stencilFillPathNV(pathObj->getPathID(), fillMode, mask);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::stencilStrokePath(const gl::ContextState &state,
                                   const gl::Path *path,
                                   GLint reference,
                                   GLuint mask)
{
    const auto *pathObj = GetImplAs<PathGL>(path);

    mFunctions->stencilStrokePathNV(pathObj->getPathID(), reference, mask);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::coverFillPath(const gl::ContextState &state,
                               const gl::Path *path,
                               GLenum coverMode)
{

    const auto *pathObj = GetImplAs<PathGL>(path);
    mFunctions->coverFillPathNV(pathObj->getPathID(), coverMode);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::coverStrokePath(const gl::ContextState &state,
                                 const gl::Path *path,
                                 GLenum coverMode)
{
    const auto *pathObj = GetImplAs<PathGL>(path);
    mFunctions->coverStrokePathNV(pathObj->getPathID(), coverMode);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::stencilThenCoverFillPath(const gl::ContextState &state,
                                          const gl::Path *path,
                                          GLenum fillMode,
                                          GLuint mask,
                                          GLenum coverMode)
{

    const auto *pathObj = GetImplAs<PathGL>(path);
    mFunctions->stencilThenCoverFillPathNV(pathObj->getPathID(), fillMode, mask, coverMode);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::stencilThenCoverStrokePath(const gl::ContextState &state,
                                            const gl::Path *path,
                                            GLint reference,
                                            GLuint mask,
                                            GLenum coverMode)
{

    const auto *pathObj = GetImplAs<PathGL>(path);
    mFunctions->stencilThenCoverStrokePathNV(pathObj->getPathID(), reference, mask, coverMode);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::coverFillPathInstanced(const gl::ContextState &state,
                                        const std::vector<gl::Path *> &paths,
                                        GLenum coverMode,
                                        GLenum transformType,
                                        const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->coverFillPathInstancedNV(static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT,
                                         &pathObjs[0], 0, coverMode, transformType,
                                         transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}
void RendererGL::coverStrokePathInstanced(const gl::ContextState &state,
                                          const std::vector<gl::Path *> &paths,
                                          GLenum coverMode,
                                          GLenum transformType,
                                          const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->coverStrokePathInstancedNV(static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT,
                                           &pathObjs[0], 0, coverMode, transformType,
                                           transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}
void RendererGL::stencilFillPathInstanced(const gl::ContextState &state,
                                          const std::vector<gl::Path *> &paths,
                                          GLenum fillMode,
                                          GLuint mask,
                                          GLenum transformType,
                                          const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->stencilFillPathInstancedNV(static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT,
                                           &pathObjs[0], 0, fillMode, mask, transformType,
                                           transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}
void RendererGL::stencilStrokePathInstanced(const gl::ContextState &state,
                                            const std::vector<gl::Path *> &paths,
                                            GLint reference,
                                            GLuint mask,
                                            GLenum transformType,
                                            const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->stencilStrokePathInstancedNV(static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT,
                                             &pathObjs[0], 0, reference, mask, transformType,
                                             transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

void RendererGL::stencilThenCoverFillPathInstanced(const gl::ContextState &state,
                                                   const std::vector<gl::Path *> &paths,
                                                   GLenum coverMode,
                                                   GLenum fillMode,
                                                   GLuint mask,
                                                   GLenum transformType,
                                                   const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->stencilThenCoverFillPathInstancedNV(
        static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT, &pathObjs[0], 0, fillMode, mask,
        coverMode, transformType, transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}
void RendererGL::stencilThenCoverStrokePathInstanced(const gl::ContextState &state,
                                                     const std::vector<gl::Path *> &paths,
                                                     GLenum coverMode,
                                                     GLint reference,
                                                     GLuint mask,
                                                     GLenum transformType,
                                                     const GLfloat *transformValues)
{
    const auto &pathObjs = GatherPaths(paths);

    mFunctions->stencilThenCoverStrokePathInstancedNV(
        static_cast<GLsizei>(pathObjs.size()), GL_UNSIGNED_INT, &pathObjs[0], 0, reference, mask,
        coverMode, transformType, transformValues);

    ASSERT(mFunctions->getError() == GL_NO_ERROR);
}

GLenum RendererGL::getResetStatus()
{
    return mFunctions->getGraphicsResetStatus();
}

void RendererGL::insertEventMarker(GLsizei length, const char *marker)
{
}

void RendererGL::pushGroupMarker(GLsizei length, const char *marker)
{
}

void RendererGL::popGroupMarker()
{
}

void RendererGL::pushDebugGroup(GLenum source, GLuint id, GLsizei length, const char *message)
{
}

void RendererGL::popDebugGroup()
{
}

std::string RendererGL::getVendorString() const
{
    return std::string(reinterpret_cast<const char *>(mFunctions->getString(GL_VENDOR)));
}

std::string RendererGL::getRendererDescription() const
{
    std::string nativeVendorString(
        reinterpret_cast<const char *>(mFunctions->getString(GL_VENDOR)));
    std::string nativeRendererString(
        reinterpret_cast<const char *>(mFunctions->getString(GL_RENDERER)));

    std::ostringstream rendererString;
    rendererString << nativeVendorString << " " << nativeRendererString << " OpenGL";
    if (mFunctions->standard == STANDARD_GL_ES)
    {
        rendererString << " ES";
    }
    rendererString << " " << mFunctions->version.major << "." << mFunctions->version.minor;
    if (mFunctions->standard == STANDARD_GL_DESKTOP)
    {
        // Some drivers (NVIDIA) use a profile mask of 0 when in compatibility profile.
        if ((mFunctions->profile & GL_CONTEXT_COMPATIBILITY_PROFILE_BIT) != 0 ||
            (mFunctions->isAtLeastGL(gl::Version(3, 2)) && mFunctions->profile == 0))
        {
            rendererString << " compatibility";
        }
        else if ((mFunctions->profile & GL_CONTEXT_CORE_PROFILE_BIT) != 0)
        {
            rendererString << " core";
        }
    }

    return rendererString.str();
}

const gl::Version &RendererGL::getMaxSupportedESVersion() const
{
    // Force generation of caps
    getNativeCaps();

    return mMaxSupportedESVersion;
}

void RendererGL::generateCaps(gl::Caps *outCaps,
                              gl::TextureCapsMap *outTextureCaps,
                              gl::Extensions *outExtensions,
                              gl::Limitations * /* outLimitations */) const
{
    nativegl_gl::GenerateCaps(mFunctions.get(), mWorkarounds, outCaps, outTextureCaps,
                              outExtensions, &mMaxSupportedESVersion,
                              &mMultiviewImplementationType);
}

GLint RendererGL::getGPUDisjoint()
{
    // TODO(ewell): On GLES backends we should find a way to reliably query disjoint events
    return 0;
}

GLint64 RendererGL::getTimestamp()
{
    GLint64 result = 0;
    mFunctions->getInteger64v(GL_TIMESTAMP, &result);
    return result;
}

void RendererGL::ensureCapsInitialized() const
{
    if (!mCapsInitialized)
    {
        generateCaps(&mNativeCaps, &mNativeTextureCaps, &mNativeExtensions, &mNativeLimitations);
        mCapsInitialized = true;
    }
}

const gl::Caps &RendererGL::getNativeCaps() const
{
    ensureCapsInitialized();
    return mNativeCaps;
}

const gl::TextureCapsMap &RendererGL::getNativeTextureCaps() const
{
    ensureCapsInitialized();
    return mNativeTextureCaps;
}

const gl::Extensions &RendererGL::getNativeExtensions() const
{
    ensureCapsInitialized();
    return mNativeExtensions;
}

const gl::Limitations &RendererGL::getNativeLimitations() const
{
    ensureCapsInitialized();
    return mNativeLimitations;
}

MultiviewImplementationTypeGL RendererGL::getMultiviewImplementationType() const
{
    ensureCapsInitialized();
    return mMultiviewImplementationType;
}

void RendererGL::applyNativeWorkarounds(gl::Workarounds *workarounds) const
{
    ensureCapsInitialized();
    nativegl_gl::ApplyWorkarounds(mFunctions.get(), workarounds);
}

angle::Result RendererGL::dispatchCompute(const gl::Context *context,
                                          GLuint numGroupsX,
                                          GLuint numGroupsY,
                                          GLuint numGroupsZ)
{
    mFunctions->dispatchCompute(numGroupsX, numGroupsY, numGroupsZ);
    return angle::Result::Continue();
}

angle::Result RendererGL::dispatchComputeIndirect(const gl::Context *context, GLintptr indirect)
{
    mFunctions->dispatchComputeIndirect(indirect);
    return angle::Result::Continue();
}

angle::Result RendererGL::memoryBarrier(GLbitfield barriers)
{
    mFunctions->memoryBarrier(barriers);
    return angle::Result::Continue();
}
angle::Result RendererGL::memoryBarrierByRegion(GLbitfield barriers)
{
    mFunctions->memoryBarrierByRegion(barriers);
    return angle::Result::Continue();
}

}  // namespace rx