XCEngine/editor/src/Viewport/SceneViewportOverlayRenderer.cpp

#include "SceneViewportOverlayRenderer.h"
#include "SceneViewportMath.h"

namespace XCEngine {
namespace Editor {

namespace {

Math::Matrix4x4 BuildOverlayViewMatrix(const SceneViewportOverlayData& overlay) {
    return BuildSceneViewportViewMatrix(overlay);
}

ImU32 ToImGuiColor(const Math::Color& color) {
    const auto toChannel = [](float value) -> int {
        return static_cast<int>(std::clamp(value, 0.0f, 1.0f) * 255.0f + 0.5f);
    };

    return IM_COL32(
        toChannel(color.r),
        toChannel(color.g),
        toChannel(color.b),
        toChannel(color.a));
}

void DrawAxisLabel(ImDrawList* drawList, const ImVec2& position, const char* label, ImU32 color) {
    if (drawList == nullptr || label == nullptr) {
        return;
    }

    const ImVec2 labelSize = ImGui::CalcTextSize(label);
    drawList->AddText(
        ImVec2(position.x - labelSize.x * 0.5f, position.y - labelSize.y * 0.5f),
        color,
        label);
}

void DrawSceneAxisWidget(
    ImDrawList* drawList,
    const SceneViewportOverlayData& overlay,
    const ImVec2& viewportMin,
    const ImVec2& viewportMax) {
    if (drawList == nullptr || !overlay.valid) {
        return;
    }

    const Math::Matrix4x4 view = BuildOverlayViewMatrix(overlay);
    const ImVec2 center(viewportMax.x - 52.0f, viewportMin.y + 52.0f);
    const float radius = 25.0f;

    drawList->AddCircleFilled(center, radius + 12.0f, IM_COL32(17, 19, 22, 178), 24);
    drawList->AddCircle(center, radius + 12.0f, IM_COL32(255, 255, 255, 30), 24, 1.0f);

    struct AxisLine {
        Math::Vector3 axis;
        const char* label;
        ImU32 color;
    };

    const AxisLine axes[] = {
        { Math::Vector3::Right(), "x", IM_COL32(239, 83, 80, 255) },
        { Math::Vector3::Up(), "y", IM_COL32(102, 187, 106, 255) },
        { Math::Vector3::Forward(), "z", IM_COL32(66, 165, 245, 255) }
    };

    for (const AxisLine& axis : axes) {
        const Math::Vector3 viewAxis = view.MultiplyVector(axis.axis);
        const ImVec2 end(
            center.x + viewAxis.x * radius,
            center.y - viewAxis.y * radius);
        drawList->AddLine(center, end, axis.color, 2.0f);
        drawList->AddCircleFilled(end, 6.0f, axis.color, 16);
        DrawAxisLabel(drawList, end, axis.label, IM_COL32(245, 245, 245, 255));
    }
}

void DrawSceneMoveGizmo(
    ImDrawList* drawList,
    const SceneViewportMoveGizmoDrawData& moveGizmo) {
    if (drawList == nullptr || !moveGizmo.visible) {
        return;
    }

    const ImVec2 pivot(moveGizmo.pivot.x, moveGizmo.pivot.y);
    drawList->AddCircleFilled(pivot, moveGizmo.pivotRadius + 1.0f, IM_COL32(20, 22, 24, 220), 20);
    drawList->AddCircle(pivot, moveGizmo.pivotRadius + 1.0f, IM_COL32(255, 255, 255, 48), 20, 1.0f);

    for (const SceneViewportMoveGizmoHandleDrawData& handle : moveGizmo.handles) {
        if (!handle.visible) {
            continue;
        }

        const ImU32 color = ToImGuiColor(handle.color);
        const float thickness = handle.active ? 4.0f : (handle.hovered ? 3.0f : 2.0f);
        const ImVec2 start(handle.start.x, handle.start.y);
        const ImVec2 end(handle.end.x, handle.end.y);
        drawList->AddLine(start, end, color, thickness);
        drawList->AddCircleFilled(end, handle.active ? 6.5f : 5.5f, color, 20);
    }
}

} // namespace

void DrawSceneViewportOverlay(
    ImDrawList* drawList,
    const SceneViewportOverlayData& overlay,
    const ImVec2& viewportMin,
    const ImVec2& viewportMax,
    const ImVec2& viewportSize,
    const SceneViewportMoveGizmoDrawData* moveGizmo) {
    if (drawList == nullptr || viewportSize.x <= 1.0f || viewportSize.y <= 1.0f) {
        return;
    }

    drawList->PushClipRect(viewportMin, viewportMax, true);
    if (overlay.valid) {
        DrawSceneAxisWidget(drawList, overlay, viewportMin, viewportMax);
    }
    if (moveGizmo != nullptr) {
        DrawSceneMoveGizmo(drawList, *moveGizmo);
    }
    drawList->PopClipRect();
}

} // namespace Editor
} // namespace XCEngine