Ogre3d /延迟渲染/点光

Question

我试图使用ogre合成器框架设置延迟渲染器。我尝试在下面的代码中实现一个点光着色器(作为一个全屏四边形效果，没有衰减或镜面计算):

向GBuffer输出延迟数据的材料:

void ToGBufferVP
                (
                    float4 iPosition : POSITION,
                    float3 iNormal : NORMAL,
                    float2 iUV0 : TEXCOORD,
                    out float4 oPosition : POSITION,
                    out float3 oViewPos : TEXCOORD0,
                    out float3 oNormal : TEXCOORD1,
                    out float2 oUV0 : TEXCOORD2,
                    uniform float4x4 cWorldViewProj,
                    uniform float4x4 cWorldView
                )
{
    oPosition = mul(cWorldViewProj, iPosition);
    oNormal = mul(cWorldView, float4(iNormal,0)).xyz;
    oViewPos = mul(cWorldView, iPosition).xyz;
    oUV0 = iUV0;
}
void ToGBufferFP
                (
                    float3 iViewPos : TEXCOORD0,
                    float3 iNormal : TEXCOORD1,
                    float2 iUV0 : TEXCOORD2,
                    out float4 oColor0 : COLOR0,
                    out float4 oColor1 : COLOR1,
                    uniform sampler2D sTex : register(s0),
                    uniform sampler2D sSpec : register(s1),
                    uniform float cFarDistance
                )
{
    oColor0.rgb = tex2D(sTex, iUV0);
    oColor0.a = tex2D(sSpec, iUV0);
    oColor1.rgb = normalize(iNormal);
    oColor1.a = length(iViewPos) / cFarDistance;
}

顶点程序描述:

vertex_program ScreenQuadDebugLight_VS cg
{
    source MyDeferredPostShader.hlsl
    profiles vs_1_1 arbvp1
    entry_point ScreenQuadDebugLight_VS
    default_params
    {
        param_named_auto worldViewProj worldviewproj_matrix
    }
}

片段程序描述:

fragment_program ScreenQuadDebugLight_PS cg
{
    source MyDeferredPostShader.hlsl
    profiles ps_2_0 arbfp1
    entry_point ScreenQuadDebugLight_PS
    default_params
    {
        param_named_auto vpWidth viewport_width
        param_named_auto vpHeight viewport_height       
        param_named_auto flip render_target_flipping
        param_named_auto farClipDistance far_clip_distance
        param_named_auto lightPos light_position_view_space 0
    }
}

轻材料脚本:

material DeferredShadingPostQuadLight
{
    technique
    {
        pass
        {
            cull_hardware none
            cull_software none
            depth_func always_pass
            vertex_program_ref ScreenQuadDebugLight_VS
            {
            }
            fragment_program_ref ScreenQuadDebugLight_PS
            {
            }
            texture_unit
            {
                tex_coord_set 0
                tex_address_mode clamp
                filtering none
            }
            texture_unit
            {
                tex_coord_set 1
                tex_address_mode clamp
                filtering none
            }
        }
    }
}

光材质:

void ScreenQuadDebugLight_VS
    (
        float4 Pos: POSITION,   
        out float4 oPos: POSITION,
        out float4 oTexCoord : TEXCOORD0,   
        uniform float4x4 worldViewProj
    )
{
    float4 projPos = mul(worldViewProj, Pos);
    oTexCoord = projPos;    
    oPos = projPos;
}
float4 ScreenQuadDebugLight_PS
    (
        float4 projPos : TEXCOORD0,
        uniform sampler Tex0: register(s0),
        uniform sampler Tex1: register(s1),
        uniform float vpWidth,
        uniform float vpHeight,
        uniform float flip,
        uniform float farClipDistance,
        uniform float3 lightPos
    ) : COLOR 
{
    // Get homogenous coordinates
    projPos.xy /= projPos.w;
    // Compensate texture coordinate half pixel jitter
    float2 texCoord = 0.5f * (float2(projPos.x, -projPos.y) + 1);
    float2 halfPixel = float2(0.5/vpWidth, 0.5/vpHeight);
    texCoord += halfPixel;
    float3 ray = float3(projPos.x, projPos.y * flip, 1);
    float4 a0 = tex2D(Tex0, texCoord); // Albedo and Specularity
    float4 a1 = tex2D(Tex1, texCoord); // Normal and Depth
    // Attributes
    float3 colour = a0.rgb;
    float specularity = a0.a;
    float distance = a1.w;
    float3 normal = a1.xyz;
    float3 viewPos = normalize(ray);
    viewPos.z = distance;
    float3 objToLightVec =  lightPos - viewPos;
    float len_sq = dot(objToLightVec, objToLightVec);
    float len = sqrt(len_sq);
    float3 objToLightDir = normalize(objToLightVec);
    float3 total_light_contrib;
    total_light_contrib = max(0.0, dot(objToLightDir, normal));
    return float4(total_light_contrib, 0.0);
}

我是这样在我的。cpp文件中声明light的:

lLightSceneNodeHolder = mSceneMgr->getRootSceneNode()->createChildSceneNode();
Ogre::Light *light;
light = mSceneMgr->createLight();
light->setType(Ogre::Light::LT_POINT);
light->setPosition(Ogre::Vector3(0, 0, -0.7f));
light->setVisible(true);
light->setDiffuseColour(Ogre::ColourValue::White);
light->setSpecularColour(Ogre::ColourValue::White);
lLightSceneNodeHolder->attachObject(light);

我得到了输出，一切都很好-除了我不能让照明正确工作。G缓冲区包含有效的数据-视图空间法线，线性z深度，纹理。我也得到光的位置在视图空间作为一个参数-然而有一些问题在矢量计算-输出不像点光应该是。我哪里做错了?

谢谢!

注:我还尝试通过合成器监听器手动传递lightPos参数，但随后光线看起来更像一个定向光…

Answer 1

问题在等式中:

float3 ray = float3(projPos.x, projPos.y * flip, 1);

它必须乘以farCorner值，即相机锥台的远角:

float3 ray = float3(projPos.x, projPos.y * flip, 1) * farCorner;

你可以使用

mCamera->getWorldSpaceCorners()[1];

，然后将其插入到排序器侦听器中，像这样:

void LightListener::notifyMaterialSetup(Ogre::uint32 pass_id, Ogre::MaterialPtr &mat)
{
    vpParams = mat->getBestTechnique()->getPass(0)->getVertexProgramParameters();
    fpParams = mat->getBestTechnique()->getPass(0)->getFragmentProgramParameters();
}
void LightListener::notifyMaterialRender(Ogre::uint32 pass_id, Ogre::MaterialPtr &mat)
{
    vpParams->setNamedConstant("lightPos", lightPos);
    fpParams->setNamedConstant("farCorner", mCamera->getWorldSpaceCorners()[1]);
}