matc: initialize CustomVariable

The default values were not provided via default construction.
Caused matc to crash on Linux.

docs/Materials.md.html

@@ -1308,7 +1308,12 @@ Description
       declare a variable called `eyeDirection` you can access it in the fragment shader using
       `variable_eyeDirection`. In the vertex shader, the interpolant name is simply a member of
       the `MaterialVertexInputs` structure (`material.eyeDirection` in your example). Each
-      interpolant is of type `float4` (`vec4`) in the shaders.
+      interpolant is of type `float4` (`vec4`) in the shaders. By default the precision of the
+      interpolant is `highp` in *both* the vertex and fragment shaders.
+      An alternate syntax can be used to specify both the name and precision of the interpolant.
+      In this case the specified precision is used as-is in both fragment and vertex stages, in
+      particular if `default` is specified the default precision is used is the fragment shader
+      (`mediump`) and in the vertex shader (`highp`).
 
 ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ JSON
 material {
@@ -1320,7 +1325,11 @@ material {
         }
     ],
     variables : [
-         eyeDirection
+         eyeDirection,
+         {
+            name : eyeColor,
+            precision : medium
+         }
     ],
     vertexDomain : device,
     depthWrite : false,

filament/backend/src/opengl/OpenGLContext.cpp

@@ -541,9 +541,6 @@ void OpenGLContext::initBugs(Bugs* bugs, Extensions const& exts,
             bugs->delay_fbo_destruction = true;
             // PowerVR seems to have no problem with this (which is good for us)
             bugs->allow_read_only_ancillary_feedback_loop = true;
-            // PowerVR doesn't respect lengths passed to glShaderSource, so concatenate them into a
-            // single string.
-            bugs->concatenate_shader_strings = true;
         } else if (strstr(renderer, "Apple")) {
             // Apple GPU
         } else if (strstr(renderer, "Tegra") ||

filament/backend/src/opengl/OpenGLContext.h

@@ -316,12 +316,6 @@ public:
         // bugs or performance issues.
         bool force_feature_level0;
 
-        // Some drivers don't respect the length argument of glShaderSource() and (apparently)
-        // require each shader source string to be null-terminated. This works around the issue by
-        // concatenating the strings into a single null-terminated string before passing it to
-        // glShaderSource().
-        bool concatenate_shader_strings;
-
     } bugs = {};
 
     // state getters -- as needed.
@@ -568,9 +562,6 @@ private:
             {   bugs.force_feature_level0,
                     "force_feature_level0",
                     ""},
-            {   bugs.concatenate_shader_strings,
-                    "concatenate_shader_strings",
-                    ""},
     }};
 
     // this is chosen to minimize code size

filament/backend/src/opengl/ShaderCompilerService.cpp

@@ -597,40 +597,30 @@ void ShaderCompilerService::compileShaders(OpenGLContext& context,
                 version = "#version 310 es\n";
             }
 
-            const std::array<const char*, 5> sources = {
-                    version.data(),
-                    prolog.data(),
-                    specializationConstantString.c_str(),
-                    packingFunctions.data(),
-                    body.data()
+            std::array<std::string_view, 5> sources = {
+                version,
+                prolog,
+                specializationConstantString,
+                packingFunctions,
+                { body.data(), body.size() - 1 }  // null-terminated
             };
 
-            const std::array<GLint, 5> lengths = {
-                    (GLint)version.length(),
-                    (GLint)prolog.length(),
-                    (GLint)specializationConstantString.length(),
-                    (GLint)packingFunctions.length(),
-                    (GLint)body.length() - 1 // null terminated
-            };
+            // Some of the sources may be zero-length. Remove them as to avoid passing lengths of
+            // zero to glShaderSource(). glShaderSource should work with lengths of zero, but some
+            // drivers instead interpret zero as a sentinel for a null-terminated string.
+            auto partitionPoint = std::stable_partition(
+                    sources.begin(), sources.end(), [](std::string_view s) { return !s.empty(); });
+            size_t count = std::distance(sources.begin(), partitionPoint);
+
+            std::array<const char*, 5> shaderStrings;
+            std::array<GLint, 5> lengths;
+            for (size_t i = 0; i < count; i++) {
+                shaderStrings[i] = sources[i].data();
+                lengths[i] = sources[i].size();
+            }
 
             GLuint const shaderId = glCreateShader(glShaderType);
-
-            if (UTILS_UNLIKELY(context.bugs.concatenate_shader_strings)) {
-                size_t totalSize = 0;
-                for (size_t i = 0; i < sources.size(); i++) {
-                    totalSize += lengths[i];
-                }
-                std::string concatenatedShaderSource;
-                concatenatedShaderSource.reserve(totalSize);
-                for (size_t i = 0; i < sources.size(); i++) {
-                    concatenatedShaderSource.append(sources[i], lengths[i]);
-                }
-                const GLchar* ptr = concatenatedShaderSource.c_str();
-                GLint length = concatenatedShaderSource.length();
-                glShaderSource(shaderId, 1, &ptr, &length);
-            } else {
-                glShaderSource(shaderId, sources.size(), sources.data(), lengths.data());
-            }
+            glShaderSource(shaderId, count, shaderStrings.data(), lengths.data());
 
             glCompileShader(shaderId);
 

filament/src/FrameSkipper.cpp

@@ -16,16 +16,22 @@
 
 #include "FrameSkipper.h"
 
-#include <utils/Log.h>
+#include <backend/DriverEnums.h>
+
+#include <utils/compiler.h>
 #include <utils/debug.h>
 
+#include <algorithm>
+
+#include <stddef.h>
+
 namespace filament {
 
 using namespace utils;
 using namespace backend;
 
 FrameSkipper::FrameSkipper(size_t latency) noexcept
-        : mLast(latency - 1) {
+        : mLast(std::max(latency, MAX_FRAME_LATENCY) - 1) {
     assert_invariant(latency <= MAX_FRAME_LATENCY);
 }
 
@@ -41,31 +47,32 @@ void FrameSkipper::terminate(DriverApi& driver) noexcept {
 
 bool FrameSkipper::beginFrame(DriverApi& driver) noexcept {
     auto& fences = mDelayedFences;
-    auto fence = fences.front();
-    if (fence) {
-        auto status = driver.getFenceStatus(fence);
-        if (status == FenceStatus::TIMEOUT_EXPIRED) {
-            // Sync not ready, skip frame
+    if (fences.front()) {
+        // Do we have a latency old fence?
+        auto status = driver.getFenceStatus(fences.front());
+        if (UTILS_UNLIKELY(status == FenceStatus::TIMEOUT_EXPIRED)) {
+            // The fence hasn't signaled yet, skip this frame
             return false;
         }
         assert_invariant(status == FenceStatus::CONDITION_SATISFIED);
-        driver.destroyFence(fence);
     }
-    // shift all fences down by 1
-    std::move(fences.begin() + 1, fences.end(), fences.begin());
-    fences.back() = {};
     return true;
 }
 
 void FrameSkipper::endFrame(DriverApi& driver) noexcept {
-    // If the user produced a new frame despite the fact that the previous one wasn't finished
-    // (i.e. FrameSkipper::beginFrame() returned false), we need to make sure to replace
-    // a fence that might be here already)
-    auto& fence = mDelayedFences[mLast];
-    if (fence) {
-        driver.destroyFence(fence);
+    auto& fences = mDelayedFences;
+    size_t const last = mLast;
+
+    // pop the oldest fence and advance the other ones
+    if (fences.front()) {
+        driver.destroyFence(fences.front());
     }
-    fence = driver.createFence();
+    std::move(fences.begin() + 1, fences.end(), fences.begin());
+
+    // add a new fence to the end
+    assert_invariant(!fences[last]);
+
+    fences[last] = driver.createFence();
 }
 
 } // namespace filament

filament/src/FrameSkipper.h

@@ -22,6 +22,9 @@
 
 #include <array>
 
+#include <stddef.h>
+#include <stdint.h>
+
 namespace filament {
 
 /*
@@ -60,7 +63,7 @@ public:
 private:
     using Container = std::array<backend::Handle<backend::HwFence>, MAX_FRAME_LATENCY>;
     mutable Container mDelayedFences{};
-    size_t mLast;
+    uint8_t const mLast;
 };
 
 } // namespace filament

filament/src/RenderPass.cpp

@@ -616,7 +616,7 @@ RenderPass::Command* RenderPass::generateCommandsImpl(RenderPass::CommandTypeFla
         //   Here, objects close to the camera (but behind) will be drawn first.
         // An alternative that keeps the mathematical ordering is given here:
         //   distanceBits ^= ((int32_t(distanceBits) >> 31) | 0x80000000u);
-        float const distance = -dot(soaWorldAABBCenter[i], cameraForward) - cameraPositionDotCameraForward;
+        float const distance = -(dot(soaWorldAABBCenter[i], cameraForward) - cameraPositionDotCameraForward);
         uint32_t const distanceBits = reinterpret_cast<uint32_t const&>(distance);
 
         // calculate the per-primitive face winding order inversion

filament/src/RendererUtils.cpp

@@ -75,7 +75,6 @@ FrameGraphId<FrameGraphTexture> RendererUtils::colorPass(
                 TargetBufferFlags const clearColorFlags = config.clearFlags & TargetBufferFlags::COLOR;
                 TargetBufferFlags clearDepthFlags = config.clearFlags & TargetBufferFlags::DEPTH;
                 TargetBufferFlags clearStencilFlags = config.clearFlags & TargetBufferFlags::STENCIL;
-                uint8_t layerCount = 1;
 
                 data.shadows = blackboard.get<FrameGraphTexture>("shadows");
                 data.ssao = blackboard.get<FrameGraphTexture>("ssao");
@@ -172,9 +171,6 @@ FrameGraphId<FrameGraphTexture> RendererUtils::colorPass(
 
                 data.color = builder.write(data.color, FrameGraphTexture::Usage::COLOR_ATTACHMENT);
                 data.depth = builder.write(data.depth, FrameGraphTexture::Usage::DEPTH_ATTACHMENT);
-                if (view.hasStereo() && engine.getConfig().stereoscopicType == StereoscopicType::MULTIVIEW) {
-                    layerCount = engine.getConfig().stereoscopicEyeCount;
-                }
 
                 /*
                  * There is a bit of magic happening here regarding the viewport used.
@@ -196,7 +192,7 @@ FrameGraphId<FrameGraphTexture> RendererUtils::colorPass(
                         .stencil = data.stencil },
                         .clearColor = config.clearColor,
                         .samples = config.msaa,
-                        .layerCount = layerCount,
+                        .layerCount = static_cast<uint8_t>(colorBufferDesc.depth),
                         .clearFlags = clearColorFlags | clearDepthFlags | clearStencilFlags});
                 blackboard["depth"] = data.depth;
             },

filament/src/ShadowMapManager.cpp

@@ -371,7 +371,13 @@ FrameGraphId<FrameGraphTexture> ShadowMapManager::render(FEngine& engine, FrameG
                     if (view.isFrontFaceWindingInverted()) {
                         renderPassFlags |= RenderPass::HAS_INVERSE_FRONT_FACES;
                     }
-                    if (mIsDepthClampSupported && engine.debug.shadowmap.depth_clamp) {
+
+                    bool const canUseDepthClamp =
+                            !view.hasVSM() &&
+                            mIsDepthClampSupported &&
+                            engine.debug.shadowmap.depth_clamp;
+
+                    if (canUseDepthClamp) {
                         renderPassFlags |= RenderPass::HAS_DEPTH_CLAMP;
                     }
 
@@ -650,9 +656,14 @@ ShadowMapManager::ShadowTechnique ShadowMapManager::updateCascadeShadowMaps(FEng
             cameraInfo.zf = -nearFarPlanes[i + 1];
             updateNearFarPlanes(&cameraInfo.cullingProjection, cameraInfo.zn, cameraInfo.zf);
 
+            bool const canUseDepthClamp =
+                    !view.hasVSM() &&
+                    mIsDepthClampSupported &&
+                    engine.debug.shadowmap.depth_clamp;
+
             auto shaderParameters = shadowMap.updateDirectional(engine,
                     lightData, 0, cameraInfo, shadowMapInfo, sceneInfo,
-                    mIsDepthClampSupported && engine.debug.shadowmap.depth_clamp);
+                    canUseDepthClamp);
 
             if (shadowMap.hasVisibleShadows()) {
                 const size_t shadowIndex = shadowMap.getShadowIndex();

filament/src/fg/PassNode.cpp

@@ -190,10 +190,10 @@ void RenderPassNode::resolve() noexcept {
                 minHeight = std::min(minHeight, h);
                 maxHeight = std::max(maxHeight, h);
             }
-            // additionally, clear implies discardStart
-            rt.backend.params.flags.discardStart |= (
-                    rt.descriptor.clearFlags & rt.targetBufferFlags);
         }
+        // additionally, clear implies discardStart
+        rt.backend.params.flags.discardStart |= (
+                rt.descriptor.clearFlags & rt.targetBufferFlags);
 
         assert_invariant(minWidth == maxWidth);
         assert_invariant(minHeight == maxHeight);

libs/filamat/include/filamat/MaterialBuilder.h

@@ -323,6 +323,9 @@ public:
     //! Custom variables (all float4).
     MaterialBuilder& variable(Variable v, const char* name) noexcept;
 
+    MaterialBuilder& variable(Variable v, const char* name,
+            ParameterPrecision precision) noexcept;
+
     /**
      * Require a specified attribute.
      *
@@ -708,11 +711,17 @@ public:
         ShaderStage stage;
     };
 
+    struct CustomVariable {
+        utils::CString name;
+        Precision precision = Precision::DEFAULT;
+        bool hasPrecision = false;
+    };
+
     static constexpr size_t MATERIAL_PROPERTIES_COUNT = filament::MATERIAL_PROPERTIES_COUNT;
     using Property = filament::Property;
 
     using PropertyList = bool[MATERIAL_PROPERTIES_COUNT];
-    using VariableList = utils::CString[MATERIAL_VARIABLES_COUNT];
+    using VariableList = CustomVariable[MATERIAL_VARIABLES_COUNT];
     using OutputList = std::vector<Output>;
 
     static constexpr size_t MAX_COLOR_OUTPUT = filament::backend::MRT::MAX_SUPPORTED_RENDER_TARGET_COUNT;

libs/filamat/src/GLSLPostProcessor.cpp

@@ -671,13 +671,15 @@ void GLSLPostProcessor::fixupClipDistance(
 // - triggers a crash on some Adreno drivers (b/291140208, b/289401984, b/289393290)
 // However Metal requires this pass in order to correctly generate half-precision MSL
 //
-// CreateSimplificationPass() creates a lot of problems:
+// Note: CreateSimplificationPass() used to creates a lot of problems:
 // - Adreno GPU show artifacts after running simplification passes (Vulkan)
 // - spirv-cross fails generating working glsl
 //      (https://github.com/KhronosGroup/SPIRV-Cross/issues/2162)
-// - generally it makes the code more complicated, e.g.: replacing for loops with
-//   while-if-break, unclear if it helps for anything.
-// However, the simplification passes below are necessary when targeting Metal, otherwise the
+//
+// However this problem was addressed in spirv-cross here:
+//      https://github.com/KhronosGroup/SPIRV-Cross/pull/2163
+//
+// The simplification passes below are necessary when targeting Metal, otherwise the
 // result is mismatched half / float assignments in MSL.
 
 
@@ -710,11 +712,11 @@ void GLSLPostProcessor::registerPerformancePasses(Optimizer& optimizer, Config c
     RegisterPass(CreateAggressiveDCEPass());
     RegisterPass(CreateRedundancyEliminationPass());
     RegisterPass(CreateCombineAccessChainsPass());
-    RegisterPass(CreateSimplificationPass(), MaterialBuilder::TargetApi::METAL);
+    RegisterPass(CreateSimplificationPass());
     RegisterPass(CreateVectorDCEPass());
     RegisterPass(CreateDeadInsertElimPass());
     RegisterPass(CreateDeadBranchElimPass());
-    RegisterPass(CreateSimplificationPass(), MaterialBuilder::TargetApi::METAL);
+    RegisterPass(CreateSimplificationPass());
     RegisterPass(CreateIfConversionPass());
     RegisterPass(CreateCopyPropagateArraysPass());
     RegisterPass(CreateReduceLoadSizePass());
@@ -723,7 +725,7 @@ void GLSLPostProcessor::registerPerformancePasses(Optimizer& optimizer, Config c
     RegisterPass(CreateRedundancyEliminationPass());
     RegisterPass(CreateDeadBranchElimPass());
     RegisterPass(CreateBlockMergePass());
-    RegisterPass(CreateSimplificationPass(), MaterialBuilder::TargetApi::METAL);
+    RegisterPass(CreateSimplificationPass());
 }
 
 void GLSLPostProcessor::registerSizePasses(Optimizer& optimizer, Config const& config) {

libs/filamat/src/MaterialBuilder.cpp

@@ -234,7 +234,21 @@ MaterialBuilder& MaterialBuilder::variable(Variable v, const char* name) noexcep
         case Variable::CUSTOM2:
         case Variable::CUSTOM3:
             assert(size_t(v) < MATERIAL_VARIABLES_COUNT);
-            mVariables[size_t(v)] = CString(name);
+            mVariables[size_t(v)] = { CString(name), Precision::DEFAULT, false };
+            break;
+    }
+    return *this;
+}
+
+MaterialBuilder& MaterialBuilder::variable(Variable v,
+        const char* name, ParameterPrecision precision) noexcept {
+    switch (v) {
+        case Variable::CUSTOM0:
+        case Variable::CUSTOM1:
+        case Variable::CUSTOM2:
+        case Variable::CUSTOM3:
+            assert(size_t(v) < MATERIAL_VARIABLES_COUNT);
+            mVariables[size_t(v)] = { CString(name), precision, true };
             break;
     }
     return *this;
@@ -1383,7 +1397,7 @@ bool MaterialBuilder::checkMaterialLevelFeatures(MaterialInfo const& info) const
 
 bool MaterialBuilder::hasCustomVaryings() const noexcept {
     for (const auto& variable : mVariables) {
-        if (!variable.empty()) {
+        if (!variable.name.empty()) {
             return true;
         }
     }

libs/filamat/src/shaders/CodeGenerator.cpp

@@ -451,15 +451,20 @@ io::sstream& CodeGenerator::generatePostProcessMain(io::sstream& out, ShaderStag
 }
 
 io::sstream& CodeGenerator::generateVariable(io::sstream& out, ShaderStage stage,
-        const CString& name, size_t index) {
-
+        const MaterialBuilder::CustomVariable& variable, size_t index) {
+    auto const& name = variable.name;
+    const char* precisionString = getPrecisionQualifier(variable.precision);
     if (!name.empty()) {
         if (stage == ShaderStage::VERTEX) {
             out << "\n#define VARIABLE_CUSTOM" << index << " " << name.c_str() << "\n";
             out << "\n#define VARIABLE_CUSTOM_AT" << index << " variable_" << name.c_str() << "\n";
-            out << "LAYOUT_LOCATION(" << index << ") VARYING vec4 variable_" << name.c_str() << ";\n";
+            out << "LAYOUT_LOCATION(" << index << ") VARYING " << precisionString << " vec4 variable_" << name.c_str() << ";\n";
         } else if (stage == ShaderStage::FRAGMENT) {
-            out << "\nLAYOUT_LOCATION(" << index << ") VARYING highp vec4 variable_" << name.c_str() << ";\n";
+            if (!variable.hasPrecision && variable.precision == Precision::DEFAULT) {
+                // for backward compatibility
+                precisionString = "highp";
+            }
+            out << "\nLAYOUT_LOCATION(" << index << ") VARYING " << precisionString << " vec4 variable_" << name.c_str() << ";\n";
         }
     }
     return out;

libs/filamat/src/shaders/CodeGenerator.h

@@ -103,7 +103,7 @@ public:
 
     // generate declarations for custom interpolants
     static utils::io::sstream& generateVariable(utils::io::sstream& out, ShaderStage stage,
-            const utils::CString& name, size_t index);
+            const MaterialBuilder::CustomVariable& variable, size_t index);
 
     // generate declarations for non-custom "in" variables
     utils::io::sstream& generateShaderInputs(utils::io::sstream& out, ShaderStage type,

libs/viewer/include/viewer/AutomationEngine.h

@@ -224,6 +224,9 @@ public:
      */
     static void exportSettings(const Settings& settings, const char* filename);
 
+    static void exportScreenshot(View* view, Renderer* renderer, std::string filename,
+            bool autoclose, AutomationEngine* automationEngine);
+
     Options getOptions() const { return mOptions; }
     bool isRunning() const { return mIsRunning; }
     size_t currentTest() const { return mCurrentTest; }

libs/viewer/src/AutomationEngine.cpp

@@ -56,7 +56,7 @@ static void convertRGBAtoRGB(void* buffer, uint32_t width, uint32_t height) {
     }
 }
 
-static void exportScreenshot(View* view, Renderer* renderer, std::string filename,
+void AutomationEngine::exportScreenshot(View* view, Renderer* renderer, std::string filename,
         bool autoclose, AutomationEngine* automationEngine) {
     const Viewport& vp = view->getViewport();
     const size_t byteCount = vp.width * vp.height * 4;
@@ -244,7 +244,8 @@ void AutomationEngine::tick(Engine* engine, const ViewerContent& content, float
     }
 
     if (mOptions.exportScreenshots) {
-        exportScreenshot(content.view, content.renderer, prefix + ".ppm", isLastTest, this);
+        AutomationEngine::exportScreenshot(
+                content.view, content.renderer, prefix + ".ppm", isLastTest, this);
     }
 
     if (isLastTest) {

samples/gltf_viewer.cpp

@@ -61,8 +61,10 @@
 #include <algorithm>
 #include <array>
 #include <fstream>
+#include <iomanip>
 #include <iostream>
 #include <set>
+#include <sstream>
 #include <string>
 
 #include "generated/resources/gltf_demo.h"
@@ -137,6 +139,8 @@ struct App {
 
     AutomationSpec* automationSpec = nullptr;
     AutomationEngine* automationEngine = nullptr;
+    bool screenshot = false;
+    uint8_t screenshotSeq = 0;
 };
 
 static const char* DEFAULT_IBL = "assets/ibl/lightroom_14b";
@@ -877,10 +881,15 @@ int main(int argc, char** argv) {
 
             if (ImGui::CollapsingHeader("Debug")) {
                 auto& debug = engine->getDebugRegistry();
-                if (ImGui::Button("Capture frame")) {
-                    bool* captureFrame =
-                            debug.getPropertyAddress<bool>("d.renderer.doFrameCapture");
-                    *captureFrame = true;
+                if (engine->getBackend() == Engine::Backend::METAL) {
+                    if (ImGui::Button("Capture frame")) {
+                        bool* captureFrame =
+                                debug.getPropertyAddress<bool>("d.renderer.doFrameCapture");
+                        *captureFrame = true;
+                    }
+                }
+                if (ImGui::Button("Screenshot")) {
+                    app.screenshot = true;
                 }
                 ImGui::Checkbox("Disable buffer padding",
                         debug.getPropertyAddress<bool>("d.renderer.disable_buffer_padding"));
@@ -1138,6 +1147,14 @@ int main(int argc, char** argv) {
     };
 
     auto postRender = [&app](Engine* engine, View* view, Scene*, Renderer* renderer) {
+        if (app.screenshot) {
+            std::ostringstream stringStream;
+            stringStream << "screenshot" << std::setfill('0') << std::setw(2) << +app.screenshotSeq;
+            AutomationEngine::exportScreenshot(
+                    view, renderer, stringStream.str() + ".ppm", false, app.automationEngine);
+            ++app.screenshotSeq;
+            app.screenshot = false;
+        }
         if (app.automationEngine->shouldClose()) {
             FilamentApp::get().close();
             return;

tools/matc/src/matc/ParametersProcessor.cpp

@@ -615,14 +615,51 @@ static bool processVariables(MaterialBuilder& builder, const JsonishValue& value
     }
 
     for (size_t i = 0; i < elements.size(); i++) {
-        auto elementValue = elements[i];
+        ParameterPrecision precision = ParameterPrecision::DEFAULT;
         MaterialBuilder::Variable v = intToVariable(i);
-        if (elementValue->getType() != JsonishValue::Type::STRING) {
+        std::string nameString;
+
+        auto elementValue = elements[i];
+        if (elementValue->getType() == JsonishValue::Type::OBJECT) {
+
+            JsonishObject const& jsonObject = *elementValue->toJsonObject();
+
+            const JsonishValue* nameValue = jsonObject.getValue("name");
+            if (!nameValue) {
+                std::cerr << "variables: entry without 'name' key." << std::endl;
+                return false;
+            }
+            if (nameValue->getType() != JsonishValue::STRING) {
+                std::cerr << "variables: name value must be STRING." << std::endl;
+                return false;
+            }
+
+            const JsonishValue* precisionValue = jsonObject.getValue("precision");
+            if (precisionValue) {
+                if (precisionValue->getType() != JsonishValue::STRING) {
+                    std::cerr << "variables: precision must be a STRING." << std::endl;
+                    return false;
+                }
+                auto precisionString = precisionValue->toJsonString();
+                if (!Enums::isValid<ParameterPrecision>(precisionString->getString())){
+                    return logEnumIssue("variables", *precisionString, Enums::map<ParameterPrecision>());
+                }
+            }
+
+            nameString = nameValue->toJsonString()->getString();
+            if (precisionValue) {
+                precision = Enums::toEnum<ParameterPrecision>(
+                        precisionValue->toJsonString()->getString());
+            }
+            builder.variable(v, nameString.c_str(), precision);
+        } else if (elementValue->getType() == JsonishValue::Type::STRING) {
+            nameString = elementValue->toJsonString()->getString();
+            builder.variable(v, nameString.c_str());
+        } else {
             std::cerr << "variables: array index " << i << " is not a STRING. found:" <<
                     JsonishValue::typeToString(elementValue->getType()) << std::endl;
             return false;
         }
-        builder.variable(v, elementValue->toJsonString()->getString().c_str());
     }
 
     return true;