我正在尝试使用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了一个点光源着色器（作为全屏四边形效果，没有衰减或高光计算）：
输出延迟数据到GBuffer的材质：
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
}
}
轻量级的材料脚本：
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
}
}
}
}
轻量级着色器：
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);
}
以下是我在 .cpp 文件中声明 light 的方法：
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，一切都正常 - 除了我无法正确地让灯光工作。G缓冲包含有效数据 - 视图空间法线、线性z深度、纹理。我还获得了视图空间中的光源位置作为参数 - 然而在向量计算过程中存在一些问题 - 输出结果与点光源应该是完全不同的。我在这里做错了什么？
谢谢！
附言：我也尝试通过合成器监听器手动传递lightPos参数，但那时候灯光看起来更像方向光...