渲染一个球

几种不同着色方法的比较：

平面法线+顶点着色(半路向量)
平面法线+面片着色
顶点法线+顶点着色
顶点法线+面片着色
Gouraud着色(平面法线+顶点着色)
Phong着色(平面法线+面片着色)

按键设置
a	d	w	s	z	x
增加theta	减少theta	增加phi	减少phi	增大半径radius	减少半径radius
v	b
增加分块	减小分块

Vertex shader:

attribute vec4 vPosition;
attribute vec4 vNormal;

varying vec4 fColor;

uniform vec4 ambientProduct, diffuseProduct, specularProduct;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
uniform vec4 lightPosition;
uniform float shininess;
uniform mat3 normalMatrix;

void main()
{
	// pos is vertex position in eye coordinates
	vec3 pos = (modelViewMatrix * vPosition).xyz;

	// vector from vertex position to light source
	vec3 L;

	// check for directional light
	if(lightPosition.w == 0.0)
	{ 
		L = normalize(lightPosition.xyz);
	}
	else
	{ 
		L = normalize( lightPosition.xyz - pos );
	}

	// Because the eye point the is at the orgin
	// the vector from the vertex position to the eye is
	vec3 E = -normalize( pos );

	// halfway vector
	vec3 H = normalize( L + E );

	// Transform vertex normal into eye coordinates
	vec3 N = normalize( normalMatrix*vNormal.xyz);

	// Compute terms in the illumination equation
	vec4 ambient = ambientProduct;

	float Kd = max( dot(L, N), 0.0 );
	vec4  diffuse = Kd*diffuseProduct;

	float Ks = pow( max(dot(N, H), 0.0), shininess );
	vec4  specular = Ks * specularProduct;

	if( dot(L, N) < 0.0 ){
		specular = vec4(0.0, 0.0, 0.0, 1.0);
	} 

	gl_Position = projectionMatrix * modelViewMatrix * vPosition;

	fColor = ambient + diffuse +specular;

	fColor.a = 1.0;
}

Fragment shader:

precision mediump float;
varying vec4 fColor;

void main()
{
	gl_FragColor = fColor;
}

attribute vec4 vPosition;
attribute vec4 vNormal;

varying vec4 fColor;

uniform vec4 ambientProduct, diffuseProduct, specularProduct;
uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
uniform vec4 lightPosition;
uniform float shininess;
uniform mat3 normalMatrix;

void main()
{
	// pos is vertex position in eye coordinates
	vec3 pos = (modelViewMatrix * vPosition).xyz;

// vector from vertex position to light source
	vec3 L;

// check for directional light
	if(lightPosition.w == 0.0)
	{ 
		L = normalize(lightPosition.xyz);
	}
	else
	{ 
		L = normalize( lightPosition.xyz - pos );
	}

// Because the eye point the is at the orgin
	// the vector from the vertex position to the eye is
	vec3 E = -normalize( pos );

// halfway vector
	vec3 H = normalize( L + E );

// Transform vertex normal into eye coordinates
	vec3 N = normalize( normalMatrix*vNormal.xyz);

// Compute terms in the illumination equation
	vec4 ambient = ambientProduct;

float Kd = max( dot(L, N), 0.0 );
	vec4  diffuse = Kd*diffuseProduct;

float Ks = pow( max(dot(N, H), 0.0), shininess );
	vec4  specular = Ks * specularProduct;

if( dot(L, N) < 0.0 ){
		specular = vec4(0.0, 0.0, 0.0, 1.0);
	}

gl_Position = projectionMatrix * modelViewMatrix * vPosition;

fColor = ambient + diffuse +specular;

fColor.a = 1.0;
}

attribute vec4 vPosition;
attribute vec4 vNormal;

varying vec4 fColor;

void main()
{
	vec3 pos = (modelViewMatrix * vPosition).xyz;
	vec3 light = lightPosition.xyz;
	vec3 L;

// check for directional light
	if(lightPosition.w == 0.0) 
		L = normalize(lightPosition.xyz);
	else 
		L = normalize( lightPosition.xyz - pos );

vec3 E = -normalize( pos );
	vec3 H = normalize( L + E );

// Transform vertex normal into eye coordinates
	vec3 N = normalize( normalMatrix*vNormal.xyz);

// Compute terms in the illumination equation
	vec4 ambient = ambientProduct;

float Kd = max( dot(L, N), 0.0 );
	vec4  diffuse = Kd*diffuseProduct;

float Ks = pow( max(dot(N, H), 0.0), shininess );
	vec4  specular = Ks * specularProduct;

if( dot(L, N) < 0.0 ) {
		specular = vec4(0.0, 0.0, 0.0, 1.0);
	}

gl_Position = projectionMatrix * modelViewMatrix * vPosition;

fColor = ambient + diffuse +specular;

fColor.a = 1.0;
}

attribute vec4 vPosition;
attribute vec4 vNormal;

uniform mat4 modelViewMatrix;
uniform mat4 projectionMatrix;
uniform mat3 normalMatrix;

uniform vec4 lightPosition;

uniform float shininess;

// material
uniform vec4 ambientProduct;
uniform vec4 diffuseProduct;
uniform vec4 specularProduct;

varying vec3 normalInterp;
varying vec4 fColor;

void main(){
	vec4 pos = modelViewMatrix * vPosition;
	normalInterp = normalize(normalMatrix * vNormal.xyz);

gl_Position = projectionMatrix * pos;

vec4 ambient = ambientProduct;

vec3 N = normalize( normalInterp );
	vec3 L;

if( lightPosition.w == 0.0 )
	{
		L = normalize( lightPosition.xyz );
	}
	else
	{
		L = normalize( lightPosition.xyz - pos.xyz );
	}

float Kd = max( dot( L, N ), 0.0 );
	vec4 diffuse = Kd * diffuseProduct;

float Ks = 0.0;
	if( Kd > 0.0 )
	{
		vec3 R = reflect( -L, N );
		vec3 E = -normalize( pos.xyz );
		float specAngle = max( dot( R, E ), 0.0 );
		Ks = pow( specAngle, shininess );
	}
	vec4 specular = Ks * specularProduct;

fColor = ambient + diffuse + specular;
	fColor.a = 1.0;
}