c – Ogre3d /延迟渲染/点光源

将延迟数据输出到GBuffer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;
}

顶点程序说明：

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
    }
}

片段程序说明：

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
            }
        }
    }
}

浅色着色器：

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);
}

这就是我在.cpp文件中声明光的方式：

lLightSceneNodeHolder = mSceneMgr->getRootSceneNode()->createChildSceneNode();

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

我得到输出,一切正常 – 除了我不能让灯光正常工作. G Buffer包含有效数据 – 视图空间法线,线性z深度,纹理.我也将视图空间中的光位置作为参数 – 但是在矢量计算期间存在一些问题 – 并且输出与点光源不同.我在这做错了什么？

谢谢！

附：我也尝试通过合成器监听器手动传递lightPos参数,但随后灯光看起来更像是定向灯……