using UnityEngine.Experimental.Rendering;
using UnityEngine.Rendering.RenderGraphModule;

namespace UnityEngine.Rendering.HighDefinition
{
    partial class VolumetricCloudsSystem
    {
        // Setup to match FORWARD_ECCENTRICITY in VolumetricCloudsUtilies.hlsl
        // Kinda empirical because they are not using the same phase function
        const float m_VolumetricCloudsAnisotropy = 0.7f;

        // Buffers required to evaluate the probe
        internal GraphicsBuffer m_CloudsDynamicProbeBuffer = null;
        internal GraphicsBuffer m_CloudsStaticProbeBuffer = null;

        void InitializeVolumetricCloudsAmbientProbe()
        {
            // Buffer is stored packed to be used directly by shader code (27 coeffs in 7 float4)
            // Compute buffer storing the pre-convolved resulting SH For volumetric lighting. L2 SH => 9 float per component.
            m_CloudsDynamicProbeBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, 7, 16);
            m_CloudsStaticProbeBuffer = new GraphicsBuffer(GraphicsBuffer.Target.Structured, 7, 16);
        }

        void ReleaseVolumetricCloudsAmbientProbe()
        {
            CoreUtils.SafeRelease(m_CloudsDynamicProbeBuffer);
            CoreUtils.SafeRelease(m_CloudsStaticProbeBuffer);
        }

        internal GraphicsBuffer RenderVolumetricCloudsAmbientProbe(RenderGraph renderGraph, HDCamera hdCamera, SkyManager skyManager, SkyUpdateContext lightingSky, bool staticSky)
        {
            // Grab the volume settings
            VolumetricClouds settings = hdCamera.volumeStack.GetComponent<VolumetricClouds>();

            // If the clouds are enabled on this camera
            GraphicsBuffer probeBuffer = staticSky ? m_CloudsStaticProbeBuffer : m_CloudsDynamicProbeBuffer;
            if (HasVolumetricClouds(hdCamera, in settings) && lightingSky.skyRenderer != null)
            {
                // We include background clouds in the ambient probe because we assume they are located above the volumetric clouds (in the background) so they should block sky light
                skyManager.RenderSkyAmbientProbe(renderGraph, lightingSky, hdCamera, probeBuffer, renderBackgroundClouds: true, HDProfileId.VolumetricCloudsAmbientProbe,
                    settings.ambientLightProbeDimmer.value, m_VolumetricCloudsAnisotropy);
            }

            return probeBuffer;
        }
    }
}