用可编程渲染管线实现phone光照模型

最新推荐文章于 2025-06-10 14:27:49 发布

最新推荐文章于 2025-06-10 14:27:49 发布 · 153 阅读

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本文详细介绍了Direct3D9中使用的光照模型，包括环境光、漫反射光和镜面反射光的计算公式及其参数说明。通过具体实例展示了如何在顶点着色器中实现点光源照明效果。

Ambient Lighting = C_a*[G_a + sum(Atti*Spoti*Lai)]

Where:

Parameter	Default value	Type	Description
C_a	(0,0,0,0)	D3DCOLORVALUE	Material ambient color
G_a	(0,0,0,0)	D3DCOLORVALUE	Global ambient color
Atten_i	(0,0,0,0)	D3DCOLORVALUE	Light attenuation of the ith light. See Attenuation and Spotlight Factor (Direct3D 9).
Spot_i	(0,0,0,0)	D3DVECTOR	Spotlight factor of the ith light. See Attenuation and Spotlight Factor (Direct3D 9).
sum	N/A	N/A	Sum of the ambient light
L_ai	(0,0,0,0)	D3DVECTOR	Light ambient color of the ith light

Diffuse Lighting = sum[C_d*L_d*(N^.L_dir)*Atten*Spot]

Parameter	Default value	Type	Description
sum	N/A	N/A	Summation of each light's diffuse component.
C_d	(0,0,0,0)	D3DCOLORVALUE	Diffuse color.
L_d	(0,0,0,0)	D3DCOLORVALUE	Light diffuse color.
N	N/A	D3DVECTOR	Vertex normal
L_dir	N/A	D3DVECTOR	Direction vector from object vertex to the light.
Atten	N/A	FLOAT	Light attenuation. See Attenuation and Spotlight Factor (Direct3D 9).
Spot	N/A	FLOAT	Spotlight factor. See Attenuation and Spotlight Factor (Direct3D 9).

Specular Lighting = C_s * sum[L_s * (N • H)^P * Atten * Spot]

The following table identifies the variables, their types, and their ranges.

Parameter	Default value	Type	Description
C_s	(0,0,0,0)	D3DCOLORVALUE	Specular color.
sum	N/A	N/A	Summation of each light's specular component.
N	N/A	D3DVECTOR	Vertex normal.
H	N/A	D3DVECTOR	Half way vector. See the section on the halfway vector.
^P	0.0	FLOAT	Specular reflection power. Range is 0 to +infinity
L_s	(0,0,0,0)	D3DCOLORVALUE	Light specular color.
Atten	N/A	FLOAT	Light attenuation value. See Attenuation and Spotlight Factor (Direct3D 9).
Spot	N/A	FLOAT	Spotlight factor. See Attenuation and Spotlight Factor (Direct3D 9).

float4x4 matViewProjection;
float4 Light_Position;
float4 Light_Attenuation;
float4 Light_Color;
float4 Ambient_Color;
float4 vViewPosition;
float alpha;

struct VS_INPUT
{
float4 Position : POSITION0;
float3 Normal : NORMAL0;
float2 Texcoord : TEXCOORD0;
};

struct VS_OUTPUT
{
float4 Position : POSITION0;
float2 Texcoord : TEXCOORD0;
float4 Color : COLOR0;
};

float4 PointLighting(float3 position, float3 normal
, float3 eyedir, float4 ambient
, float3 lightpos, float3 lightatt, float4 lightcolor)
{
float3 lightdir = normalize(position - lightpos);
float3 dis = distance(position, lightpos);
float disatt = saturate(1 / ( lightatt.x + lightatt.y * dis + lightatt.z * dis * dis ));
float angleatt = saturate(-lightdir * normal);
float3 reflectdir = normalize(reflect(lightdir, normal));
float specularatt = pow(saturate(reflectdir * eyedir), alpha);

return ambient + lightcolor * disatt * (angleatt + specularatt);
}

VS_OUTPUT vs_main( VS_INPUT Input )
{
VS_OUTPUT Output;

Output.Position = mul( Input.Position, matViewProjection );
Output.Texcoord = Input.Texcoord;
float3 eyedir = normalize(vViewPosition - Input.Position);
Output.Color = PointLighting(Input.Position, Input.Normal
, eyedir, Ambient_Color
, Light_Position, Light_Attenuation, Light_Color);

return( Output );

}