RendererFeatureでMRT(Multiple Render Target)

　通常は一つのレンダーターゲットに対して描画を行います。これに対し、MRT(Multiple Render Target)では複数のレンダーターゲットへ一度に描画することができます。このMRTをRenderFeature内でCommandBufferを使用して実行します。これは、Library¥PackageCache¥com.unity.render-pipelines.universal@7.7.1¥Runtime¥PassesにあるPostProcessPass.cs内のDoGaussianDepthOfFieldで使用されています。これを参考にScriptとShaderを作成し、MRTが実行できるか確認をしました。

1. Shader
2. Script
3. 実行結果

Shader

　MRTを実行するためのShaderは以下の通りです。通常、フラグメントシェーダーの戻り値はfixed4やfloat4などのベクトル型ですが、MRT用のShaderではフラグメントシェーダーの戻り値として複数のベクトル型の変数を持つstruct使用します。このShaderではMainTexをグレースケール化した結果とグレースケールを反転した結果を出力します。

Shader "Hidden/Karakan/PostProcessing/MRT"
{
    SubShader
    {
        Tags { "RenderType"="Opaque" }

        Cull Off ZWrite Off ZTest Always

        Pass
        {
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag
            #pragma target 3.5

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityInput.hlsl"   

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct Varyings
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            struct output
            {
                float4 color0 : COLOR0;
                float4 color1 : COLOR1;
            };

            CBUFFER_START(UnityPerMaterial)
        
            TEXTURE2D(_MainTex);
            SAMPLER(sampler_MainTex);
            float4 _MainTex_ST;
        
            TEXTURE2D(_PrimaryTex);
            SAMPLER(sampler_PrimaryTex);
            float4 _PrimaryTex_ST;
        
            TEXTURE2D(_SecondaryTex);
            SAMPLER(sampler_SecondaryTex);
            float4 _SecondaryTex_ST;

            CBUFFER_END

            Varyings  vert (appdata v)
            {
                Varyings o;
                o.vertex = TransformObjectToHClip(v.vertex.xyz);
                o.uv = TRANSFORM_TEX(v.uv, _MainTex);
                return o;
            }

            output frag (Varyings i)
            {
                output o;

                float4 col_main = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv);

                float4 col_grayscale;
                col_grayscale.rgb = col_main.r * 0.2126 + col_main.g * 0.7152 + col_main.b * col_main.b * 0.0722;
                col_grayscale.a = col_main.a;

                o.color0 = col_grayscale;
                o.color1 = 1.0 - col_grayscale;

                return o;
            }
            ENDHLSL
        }
    }
}

Shader "Hidden/Karakan/PostProcessing/MRT"

{

SubShader

{

Tags { "RenderType"="Opaque" }

Cull Off ZWrite Off ZTest Always

Pass

{

HLSLPROGRAM

#pragma vertex vert

#pragma fragment frag

#pragma target 3.5

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityInput.hlsl"

struct appdata

{

float4 vertex : POSITION;

float2 uv : TEXCOORD0;

};

struct Varyings

{

float2 uv : TEXCOORD0;

float4 vertex : SV_POSITION;

};

struct output

{

float4 color0 : COLOR0;

float4 color1 : COLOR1;

};

CBUFFER_START(UnityPerMaterial)

TEXTURE2D(_MainTex);

SAMPLER(sampler_MainTex);

float4 _MainTex_ST;

TEXTURE2D(_PrimaryTex);

SAMPLER(sampler_PrimaryTex);

float4 _PrimaryTex_ST;

TEXTURE2D(_SecondaryTex);

SAMPLER(sampler_SecondaryTex);

float4 _SecondaryTex_ST;

CBUFFER_END

Varyings vert (appdata v)

{

Varyings o;

o.vertex = TransformObjectToHClip(v.vertex.xyz);

o.uv = TRANSFORM_TEX(v.uv, _MainTex);

return o;

}

output frag (Varyings i)

{

output o;

float4 col_main = SAMPLE_TEXTURE2D(_MainTex, sampler_MainTex, i.uv);

float4 col_grayscale;

col_grayscale.rgb = col_main.r * 0.2126 + col_main.g * 0.7152 + col_main.b * col_main.b * 0.0722;

col_grayscale.a = col_main.a;

o.color0 = col_grayscale;

o.color1 = 1.0 - col_grayscale;

return o;

}

ENDHLSL

}

以下はMRTの結果を確認するためのShaderです。二つのテクスチャを左右に分けて表示します。

Shader "Hidden/Karakan/PostProcessing/Combine"
{
    SubShader
    {
        Tags { "RenderType"="Opaque" }

        Cull Off ZWrite Off ZTest Always

        Pass
        {
            HLSLPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"
            #include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityInput.hlsl"   

            struct appdata
            {
                float4 vertex : POSITION;
                float2 uv : TEXCOORD0;
            };

            struct Varyings
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            CBUFFER_START(UnityPerMaterial)
        
            TEXTURE2D(_PrimaryTex);
            SAMPLER(sampler_PrimaryTex);
            float4 _PrimaryTex_ST;
        
            TEXTURE2D(_SecondaryTex);
            SAMPLER(sampler_SecondaryTex);
            float4 _SecondaryTex_ST;

            CBUFFER_END

            Varyings  vert (appdata v)
            {
                Varyings o;
                o.vertex = TransformObjectToHClip(v.vertex.xyz);
                o.uv = TRANSFORM_TEX(v.uv, _PrimaryTex);
                return o;
            }

            float4 frag (Varyings i) : SV_Target
            {
                float4 col_prim = SAMPLE_TEXTURE2D(_PrimaryTex, sampler_PrimaryTex, i.uv);
                float4 col_second = SAMPLE_TEXTURE2D(_SecondaryTex, sampler_SecondaryTex, i.uv);

                float t = step(0.5, i.uv.x);
                float4 col = col_prim * (1.0 - t) + col_second * t;

                return col;
            }
            ENDHLSL
        }
    }
}

Shader "Hidden/Karakan/PostProcessing/Combine"

{

SubShader

{

Tags { "RenderType"="Opaque" }

Cull Off ZWrite Off ZTest Always

Pass

{

HLSLPROGRAM

#pragma vertex vert

#pragma fragment frag

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/Core.hlsl"

#include "Packages/com.unity.render-pipelines.universal/ShaderLibrary/UnityInput.hlsl"

struct appdata

{

float4 vertex : POSITION;

float2 uv : TEXCOORD0;

};

struct Varyings

{

float2 uv : TEXCOORD0;

float4 vertex : SV_POSITION;

};

CBUFFER_START(UnityPerMaterial)

TEXTURE2D(_PrimaryTex);

SAMPLER(sampler_PrimaryTex);

float4 _PrimaryTex_ST;

TEXTURE2D(_SecondaryTex);

SAMPLER(sampler_SecondaryTex);

float4 _SecondaryTex_ST;

CBUFFER_END

Varyings vert (appdata v)

{

Varyings o;

o.vertex = TransformObjectToHClip(v.vertex.xyz);

o.uv = TRANSFORM_TEX(v.uv, _PrimaryTex);

return o;

}

float4 frag (Varyings i) : SV_Target

{

float4 col_prim = SAMPLE_TEXTURE2D(_PrimaryTex, sampler_PrimaryTex, i.uv);

float4 col_second = SAMPLE_TEXTURE2D(_SecondaryTex, sampler_SecondaryTex, i.uv);

float t = step(0.5, i.uv.x);

float4 col = col_prim * (1.0 - t) + col_second * t;

return col;

}

ENDHLSL

}

Script

　Scriptは以下の通りです。

using UnityEngine;
using UnityEngine.Rendering;
using UnityEngine.Rendering.Universal;

public class MrtRenderPassFeature : ScriptableRendererFeature
{
    class MrtRenderPass : ScriptableRenderPass
    {
        const string _render_tag = "MrtRenderPass";

        RenderTargetIdentifier _currentTarget;

        int _dest_01_id = Shader.PropertyToID("_MrtTempTexture01");
        int _dest_02_id = Shader.PropertyToID("_MrtTempTexture02");
        int _depth_id = Shader.PropertyToID("_MrtTempTexture03");

        //shader property id
        int _prop_id_main = Shader.PropertyToID("_MainTex");
        int _prop_id_primary = Shader.PropertyToID("_PrimaryTex");
        int _prop_id_secondary = Shader.PropertyToID("_SecondaryTex");

        Material _mat_mrt, _mat_comb;

        Mesh _screen_mesh;

        public MrtRenderPass()
        {
            _mat_mrt = CreateMaterial("Hidden/Karakan/PostProcessing/MRT");
            _mat_comb = CreateMaterial("Hidden/Karakan/PostProcessing/Combine");
        }

        Material CreateMaterial(string path)
        {
            Shader shader = Shader.Find(path);
            if (shader == null)
            {
                Debug.LogError("Shader not found.");
                return null;
            }
            Material mat = new Material(shader);
            if (mat == null)
            {
                Debug.LogError("Material has not been created.");
                return null;
            }
            return mat;
        }

        public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)
        {
            if (_mat_mrt == null)
            {
                Debug.LogError("Material has not been created.");
                return;
            }

            if (!renderingData.cameraData.postProcessEnabled) return;


            CommandBuffer cmd = CommandBufferPool.Get(_render_tag);
            cmd.name = "MRT Buffer";

            Render(cmd, ref renderingData);
            context.ExecuteCommandBuffer(cmd);
            CommandBufferPool.Release(cmd);

            context.Submit();
        }

        void Render(CommandBuffer cmd, ref RenderingData renderingData)
        {
            int width = renderingData.cameraData.camera.scaledPixelWidth;
            int height = renderingData.cameraData.camera.scaledPixelHeight;
            cmd.GetTemporaryRT(_dest_01_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);
            cmd.GetTemporaryRT(_dest_02_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);
            cmd.GetTemporaryRT(_depth_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);

            RenderTargetIdentifier[] buffers = { new RenderTargetIdentifier(_dest_01_id), new RenderTargetIdentifier(_dest_02_id) };

            cmd.SetGlobalTexture(_prop_id_main, _currentTarget);
            cmd.SetGlobalTexture(_prop_id_primary, _dest_01_id);
            cmd.SetGlobalTexture(_prop_id_secondary, _dest_02_id);

            cmd.SetViewProjectionMatrices(Matrix4x4.identity, Matrix4x4.identity); //2Dとして描画
            cmd.SetViewport(renderingData.cameraData.camera.pixelRect);
            cmd.SetRenderTarget(buffers, _depth_id);
            cmd.DrawMesh(ScreenMesh(), Matrix4x4.identity, _mat_mrt);
            cmd.SetViewProjectionMatrices(renderingData.cameraData.camera.worldToCameraMatrix, renderingData.cameraData.camera.projectionMatrix);

            cmd.Blit(null, _currentTarget, _mat_comb);

            cmd.ReleaseTemporaryRT(_dest_01_id);
            cmd.ReleaseTemporaryRT(_dest_02_id);
            cmd.ReleaseTemporaryRT(_depth_id);
        }

        public void Setup(in RenderTargetIdentifier currentTarget)
        {
            _currentTarget = currentTarget;
        }

        public Mesh ScreenMesh()
        {
            if (_screen_mesh != null) return _screen_mesh;

            _screen_mesh = new Mesh { name = "Screen Mesh" };
            _screen_mesh.SetVertices(new Vector3[]
            {
                    new Vector3(-1.0f, -1.0f, 0.0f),
                    new Vector3(-1.0f,  1.0f, 0.0f),
                    new Vector3( 1.0f, -1.0f, 0.0f),
                    new Vector3( 1.0f,  1.0f, 0.0f),
            });

            _screen_mesh.SetUVs(0, new Vector2[]
            {
                    new Vector2(0.0f, 0.0f),
                    new Vector2(0.0f, 1.0f),
                    new Vector2(1.0f, 0.0f),
                    new Vector2(1.0f, 1.0f),
            });

            _screen_mesh.SetIndices(new int[] { 0, 1, 2, 2, 1, 3 }, MeshTopology.Triangles, 0, false);
            _screen_mesh.UploadMeshData(true);

            return _screen_mesh;
        }
    }

    MrtRenderPass m_ScriptablePass;

    public override void Create()
    {
        m_ScriptablePass = new MrtRenderPass();
        m_ScriptablePass.renderPassEvent = RenderPassEvent.AfterRenderingTransparents;
    }

    public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)
    {
        m_ScriptablePass.Setup(renderer.cameraColorTarget);
        renderer.EnqueuePass(m_ScriptablePass);
    }
}

100

101

102

103

104

105

106

107

108

109

110

111

112

113

114

115

116

117

118

119

120

121

122

123

124

125

126

127

128

129

130

131

132

133

134

135

136

137

138

139

140

141

142

143

using UnityEngine;

using UnityEngine.Rendering;

using UnityEngine.Rendering.Universal;

public class MrtRenderPassFeature : ScriptableRendererFeature

{

class MrtRenderPass : ScriptableRenderPass

{

const string _render_tag = "MrtRenderPass";

RenderTargetIdentifier _currentTarget;

int _dest_01_id = Shader.PropertyToID("_MrtTempTexture01");

int _dest_02_id = Shader.PropertyToID("_MrtTempTexture02");

int _depth_id = Shader.PropertyToID("_MrtTempTexture03");

//shader property id

int _prop_id_main = Shader.PropertyToID("_MainTex");

int _prop_id_primary = Shader.PropertyToID("_PrimaryTex");

int _prop_id_secondary = Shader.PropertyToID("_SecondaryTex");

Material _mat_mrt, _mat_comb;

Mesh _screen_mesh;

public MrtRenderPass()

{

_mat_mrt = CreateMaterial("Hidden/Karakan/PostProcessing/MRT");

_mat_comb = CreateMaterial("Hidden/Karakan/PostProcessing/Combine");

}

Material CreateMaterial(string path)

{

Shader shader = Shader.Find(path);

if (shader == null)

{

Debug.LogError("Shader not found.");

return null;

}

Material mat = new Material(shader);

if (mat == null)

{

Debug.LogError("Material has not been created.");

return null;

}

return mat;

}

public override void Execute(ScriptableRenderContext context, ref RenderingData renderingData)

{

if (_mat_mrt == null)

{

Debug.LogError("Material has not been created.");

return;

}

if (!renderingData.cameraData.postProcessEnabled) return;

CommandBuffer cmd = CommandBufferPool.Get(_render_tag);

cmd.name = "MRT Buffer";

Render(cmd, ref renderingData);

context.ExecuteCommandBuffer(cmd);

CommandBufferPool.Release(cmd);

context.Submit();

}

void Render(CommandBuffer cmd, ref RenderingData renderingData)

{

int width = renderingData.cameraData.camera.scaledPixelWidth;

int height = renderingData.cameraData.camera.scaledPixelHeight;

cmd.GetTemporaryRT(_dest_01_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);

cmd.GetTemporaryRT(_dest_02_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);

cmd.GetTemporaryRT(_depth_id, width, height, 0, FilterMode.Bilinear, RenderTextureFormat.ARGBFloat);

RenderTargetIdentifier[] buffers = { new RenderTargetIdentifier(_dest_01_id), new RenderTargetIdentifier(_dest_02_id) };

cmd.SetGlobalTexture(_prop_id_main, _currentTarget);

cmd.SetGlobalTexture(_prop_id_primary, _dest_01_id);

cmd.SetGlobalTexture(_prop_id_secondary, _dest_02_id);

cmd.SetViewProjectionMatrices(Matrix4x4.identity, Matrix4x4.identity); //2Dとして描画

cmd.SetViewport(renderingData.cameraData.camera.pixelRect);

cmd.SetRenderTarget(buffers, _depth_id);

cmd.DrawMesh(ScreenMesh(), Matrix4x4.identity, _mat_mrt);

cmd.SetViewProjectionMatrices(renderingData.cameraData.camera.worldToCameraMatrix, renderingData.cameraData.camera.projectionMatrix);

cmd.Blit(null, _currentTarget, _mat_comb);

cmd.ReleaseTemporaryRT(_dest_01_id);

cmd.ReleaseTemporaryRT(_dest_02_id);

cmd.ReleaseTemporaryRT(_depth_id);

}

public void Setup(in RenderTargetIdentifier currentTarget)

{

_currentTarget = currentTarget;

}

public Mesh ScreenMesh()

{

if (_screen_mesh != null) return _screen_mesh;

_screen_mesh = new Mesh { name = "Screen Mesh" };

_screen_mesh.SetVertices(new Vector3[]

{

new Vector3(-1.0f, -1.0f, 0.0f),

new Vector3(-1.0f, 1.0f, 0.0f),

new Vector3( 1.0f, -1.0f, 0.0f),

new Vector3( 1.0f, 1.0f, 0.0f),

});

_screen_mesh.SetUVs(0, new Vector2[]

{

new Vector2(0.0f, 0.0f),

new Vector2(0.0f, 1.0f),

new Vector2(1.0f, 0.0f),

new Vector2(1.0f, 1.0f),

});

_screen_mesh.SetIndices(new int[] { 0, 1, 2, 2, 1, 3 }, MeshTopology.Triangles, 0, false);

_screen_mesh.UploadMeshData(true);

return _screen_mesh;

}

MrtRenderPass m_ScriptablePass;

public override void Create()

{

m_ScriptablePass = new MrtRenderPass();

m_ScriptablePass.renderPassEvent = RenderPassEvent.AfterRenderingTransparents;

}

public override void AddRenderPasses(ScriptableRenderer renderer, ref RenderingData renderingData)

{

m_ScriptablePass.Setup(renderer.cameraColorTarget);

renderer.EnqueuePass(m_ScriptablePass);

}

以下の部分でMRTを行っています。SetRenderTargetによって複数のレンダーターゲットを設定します。そして、スクリーンに広がるメッシュをMRT用のマテリアルで描画することで複数のレンダーターゲットへ描画できます。

cmd.SetViewProjectionMatrices(Matrix4x4.identity, Matrix4x4.identity); //2Dとして描画
cmd.SetViewport(renderingData.cameraData.camera.pixelRect);
cmd.SetRenderTarget(buffers, _depth_id);
cmd.DrawMesh(ScreenMesh(), Matrix4x4.identity, _mat_mrt);
cmd.SetViewProjectionMatrices(renderingData.cameraData.camera.worldToCameraMatrix, renderingData.cameraData.camera.projectionMatrix);