最终效果：
本Shader算法参考自Shadertoy， 原地址：https://www.shadertoy.com/view/XsfGRn
Shader的实现：
vs: heart.vert
attribute vec4 a_position;
attribute vec2 a_texCoord;
#ifdef GL_ES
varying lowp vec2 v_texCoord;
#else
varying vec2 v_texCoord;
#endif
void main()
{
gl_Position = CC_PMatrix * a_position;
v_texCoord = a_texCoord;
}
```
ps:heart.frag
#ifdef GL_ES
varying lowp vec2 v_texCoord;
#else
varying vec2 v_texCoord;
#endif
uniform vec2 u_screenSize;//视口大小，Director::getInstance()->getVisibleSize();
//uniform vec4 u_heartColor;
uniform float u_heartColorR;//heart的RGB值
uniform float u_heartColorG;
uniform float u_heartColorB;
void main()
{
vec4 u_heartColor = vec4(u_heartColorR, u_heartColorG, u_heartColorB, 1.);
vec2 fragCoord = vec2(v_texCoord.x, 1-v_texCoord.y)*u_screenSize.xy;
vec4 u_bgColor = vec4(1.0);//背景颜色
float _Blur = 0.02;//heart边缘模糊大小
float _Duration = 1.5;//跳动周期
vec2 p = (2.0*fragCoord.xy-u_screenSize.xy)/min(u_screenSize.y,u_screenSize.x);
p.y -= 0.25;
// heart跳动算法
float tt = mod(CC_Time.y,1.5)/1.5;
tt = mod(CC_Time.y,_Duration)/_Duration;
float ss = pow(tt,.2)*0.5 + 0.5;
ss = 1.0 + ss*0.5*sin(tt*6.2831*3.0 + p.y*0.5)*exp(-tt*4.0);
p *= vec2(0.5,1.5) + ss*vec2(0.5,-0.5);
// heart形状算法
float a = atan(p.x,p.y)/3.141593;
float r = length(p);
float h = abs(a);
float d = (13.0*h - 22.0*h*h + 10.0*h*h*h)/(6.0-5.0*h);
// Color
float s = 1.0-0.5*clamp(r/d,0.0,1.0);
s = 0.75 + 0.75*p.x;
s *= 1.0-0.25*r;
s = 0.5 + 0.6*s;
s *= 0.5+0.5*pow( 1.0-clamp(r/d, 0.0, 1.0 ), 0.1 );
vec3 hcol = vec3(1.0,0.5*r,0.3)*s;
hcol = u_heartColor.xyz *s;
vec3 col = mix( u_bgColor.xyz, hcol, smoothstep( -0.01, 0.01, d - r) );
col = mix( u_bgColor.xyz, hcol, smoothstep( -_Blur, _Blur, d - r) );
vec4 texColor = texture2D(CC_Texture0, v_texCoord);
gl_FragColor = texColor * vec4(col, 1.0);
}
```
2.应用Shader：
auto bg = Sprite::create("HelloWorld.png");
bg->setPosition(winSize / 2);
this->addChild(bg);
auto programState = GLProgramState::getOrCreateWithGLProgram(GLProgram::createWithFilenames("shader/heart.vert", "shader/heart.frag"));
//heart animation
programState->setUniformVec2("u_screenSize", Director::getInstance()->getWinSize());
programState->setUniformFloat("u_heartColorR", 1.0);//RGB值传入Shader
programState->setUniformFloat("u_heartColorG", 0.0);
programState->setUniformFloat("u_heartColorB", 0.0);
programState->applyUniforms();
bg->setGLProgramState(programState);
```
原文地址：http://blog.csdn.net/final5788