c# - 使用自定义着色器会导致黑色图像

Question

我使用 unity 2018.3.5f1。我想在渲染图像时覆盖自定义着色器。以下是我的 onRenderImage 函数。

void OnRenderImage(RenderTexture src, RenderTexture dest) {
        // shaderMaterial renders the image with Barrel distortion and disparity effect
        Graphics.Blit(camTextureHolder.mainTexture, nullRenderTexture, shaderMaterial);

        // measure average frames per second
        m_FpsAccumulator++;
        if (Time.realtimeSinceStartup > m_FpsNextPeriod) {
            m_CurrentFps = (int)(m_FpsAccumulator / fpsMeasurePeriod);
            m_FpsAccumulator = 0;
            m_FpsNextPeriod += fpsMeasurePeriod;
        }
    }

问题是在我尝试这样做时整个屏幕看起来都是黑色的。我可以知道如何解决这个问题吗？

更新:

这是我正在使用的着色器的代码

Shader "Custom/FakeAR"
{
    Properties{
        _MainTex("", 2D) = "white" {}
        [HideInInspector]_FOV("FOV", Range(1, 2)) = 1.6
        [HideInInspector]_Disparity("Disparity", Range(0, 0.3)) = 0.1
        [HideInInspector]_Alpha("Alpha", Range(0, 2.0)) = 1.0
    }

SubShader{

    Pass{
        CGPROGRAM
        #pragma vertex vert
        #pragma fragment frag
        #include "UnityCG.cginc"

        struct v2f {
            float4 pos : POSITION;
            float2 uv : TEXCOORD0;
        };

        // Default Vertex Shader 
        v2f vert(appdata_img v) {
            v2f o;
            o.pos = UnityObjectToClipPos(v.vertex);
            o.uv = MultiplyUV(UNITY_MATRIX_TEXTURE0, v.texcoord.xy);
            return o;
        }

        // Parameters
        sampler2D _MainTex;
        float _FOV;

        // Alpha is the ratio of pixel density: width to height
        float _Alpha;
        // Disparity is the portion to separate
        // larger disparity cause closer stereovision
        float _Disparity;


        // Fragment Shader: Remap the texture coordinates to combine
        // barrel distortion and disparity video display
        fixed4 frag(v2f i) : COLOR {
            float2 uv1, uv2, uv3;
            float t1, t2;
            float offset;

            // uv1 is the remap of left and right screen to a full screen 
            uv1 = i.uv - 0.5;
            uv1.x = uv1.x * 2 - 0.5 + sign(i.uv.x < 0.5);

            t1 = sqrt(1.0 - uv1.x * uv1.x - uv1.y * uv1.y);
            t2 = 1.0 / (t1 * tan(_FOV * 0.5));

            // uv2 is the remap of side screen with barrel distortion
            uv2 = uv1 * t2 + 0.5;

            // black color for out-of-range pixels
            if (uv2.x >= 1 || uv2.y >= 1 || uv2.x <= 0 || uv2.y <= 0) {
                return fixed4(0, 0, 0, 1);
            }
            else {
                offset = 0.5 - _Alpha * 0.5 + _Disparity * 0.5 - _Disparity * sign(i.uv.x < 0.5);
                // uv3 is the remap of image texture
                uv3 = uv2;
                uv3.x = uv2.x * _Alpha + offset;
                return tex2D(_MainTex, uv3);
            }               
        }
        ENDCG
    }
}
FallBack "Diffuse"

是不是shader的原因？

Answer 1

好吧，我认为它正在工作，只是着色器没有任何要渲染的东西，这意味着它会变成黑色。您可能希望着色器使用现有的相机纹理。那么也许是这个？

void OnRenderImage(RenderTexture src, RenderTexture dest) {
        // shaderMaterial renders the image with Barrel distortion and disparity effect
        Graphics.Blit(src, dst, shaderMaterial);

        // measure average frames per second
        m_FpsAccumulator++;
        if (Time.realtimeSinceStartup > m_FpsNextPeriod) {
            m_CurrentFps = (int)(m_FpsAccumulator / fpsMeasurePeriod);
            m_FpsAccumulator = 0;
            m_FpsNextPeriod += fpsMeasurePeriod;
        }
    }

尝试让着色器真正成为默认值，看看它是否渲染了一些东西。所以尝试一个看起来像这样的着色器:

Shader "Examples/ExampleDisplacement"
{
    Properties
    {
        _MainTex("Texture", 2D) = "white" {}
    }
    SubShader
    {
        // No culling or depth
        Cull Off ZWrite Off ZTest Always

        Pass
        {
            CGPROGRAM
            #pragma vertex vert
            #pragma fragment frag

            #include "UnityCG.cginc"

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

            struct v2f
            {
                float2 uv : TEXCOORD0;
                float4 vertex : SV_POSITION;
            };

            v2f vert (appdata v)
            {
                v2f o;
                o.vertex = UnityObjectToClipPos(v.vertex);
                o.uv = v.uv;
                return o;
            }

            sampler2D _MainTex;

            float4 frag (v2f i) : SV_Target
            {
                float4 col = tex2D(_MainTex, i.uv);
                return col;
            }
            ENDCG
        }
    }
}