图形学学习笔记2(cel-shading分析)
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// -------------------------------
// Cel Shading Section
// -------------------------------
vertex_program Ogre/CelShadingVP cg
{
source Example_CelShading.cg
entry_point main_vp
profiles vs_1_1 arbvp1
default_params
{
param_named_auto lightPosition light_position_object_space 0 param_named_auto eyePosition camera_position_object_space
param_named_auto worldViewProj worldviewproj_matrix
param_named shininess float 10
}
}
fragment_program Ogre/CelShadingFP cg
{
source Example_CelShading.cg
entry_point main_fp
profiles ps_1_1 arbfp1 fp20
}
material Examples/CelShading
{
technique
{
pass
{
vertex_program_ref Ogre/CelShadingVP
{
// map shininess from custom renderable param 1
param_named_auto shininess custom 1
// 终于知道param_named_auto第三个参数的作用了，用于给程序中赋值的索引
sub->setCustomParameter(CUSTOM_SHININESS, Vector4( 10.0f , 0.0f , 0.0f , 0.0f )); CUSTOM_SHININESS == 1
}
fragment_program_ref Ogre/CelShadingFP
{
// map diffuse from custom renderable param 2
param_named_auto diffuse custom 2
// map specular from custom renderable param 2
param_named_auto specular custom 3
}
texture_unit
{
texture cel_shading_diffuse.png 1d
tex_address_mode clamp
filtering none
}
texture_unit
{
texture cel_shading_specular.png 1d
tex_address_mode clamp
filtering none
}
texture_unit
{
texture cel_shading_edge.png 1d
tex_address_mode clamp
filtering none
}
}
}
}
////////////////////////////////////////////////////////////////////////////////////下面是cg文件
////////////////////////////////////////////////////////////////////////////////
/* Cel shading vertex program for single-pass rendering
In this program, we want to calculate the diffuse and specular
ramp components, and the edge factor (for doing simple outlining)
For the outlining to look good, we need a pretty well curved model.
*/
void main_vp(float4 position : POSITION,
float3 normal : NORMAL,[U1]
// outputs
out float4 oPosition : POSITION,
out float diffuse : TEXCOORD0,
out float specular : TEXCOORD1,
out float edge : TEXCOORD2,[U2]
// parameters
uniform float3 lightPosition, // object space：世界坐标系
uniform float3 eyePosition, // object space
uniform float4 shininess,
uniform float4x4 worldViewProj)
{
// calculate output position
oPosition = mul(worldViewProj, position);
// calculate light vector
float3 N = normalize(normal);
float 3 L = normalize(lightPosition - position.xyz);
// Calculate diffuse component
diffuse = max(dot(N, L) , 0);
// Calculate specular component
float3 E = normalize(eyePosition - position.xyz);
float3 H = normalize(L + E);
specular = pow(max(dot(N, H), 0), shininess[U3] );
// Mask off specular if diffuse is 0
if (diffuse == 0) specular = 0;
// Edge detection, dot eye and normal vectors
edge = max(dot(N, E), 0); // 法线与视线平行的点认为是标远，给予黑色沟边
}
void main_fp(float diffuseIn : TEXCOORD0,
float specularIn : TEXCOORD1,
float edge : TEXCOORD2,
[U4]
out float4 colour : COLOR,
uniform float4 diffuse,
uniform float4 specular,
uniform sampler1D diffuseRamp,
uniform sampler1D specularRamp,
uniform sampler1D edgeRamp[U5] )
{
// Step functions from textures
diffuseIn = tex1D(diffuseRamp, diffuseIn).x;
specularIn = tex1D(specularRamp, specularIn).x;
edge = tex1D(edgeRamp, edge).x;
colour = edge * ((diffuse * diffuseIn) +
(specular * specularIn));
}
[U1]这里是GPU传进来的，POSITION：顶点坐标，NORMAL法线，去看看hlsl的语意定义
[U2]out都是输出参数，改变他们的值输出之后被ps获取
[U3]即m下标gls，为材料的光泽度
[U4]得到的是vs中out出来的值
[U5]从texture_unit中得到，顺序根据定义的顺序texture_unit
{
texture cel_shading_diffuse.png 1d
tex_address_mode clamp
filtering none
}
texture_unit
{
texture cel_shading_specular.png 1d
tex_address_mode clamp
filtering none
}
texture_unit
{
texture cel_shading_edge.png 1d
tex_address_mode clamp
filtering none
}