Use kanzi's shader shader: finish digging a circle in the picture

Writing materials in kanzi is a way for us to achieve cool effects. Basically, most of the simple effects in opengl can be realized in kanzi. The following is a picture that only shows the effect of a part of the picture, which is quite Yu dug a hole in the picture

Vertex shader :

attribute vec3 kzPosition;
attribute vec2 kzTextureCoordinate0;
uniform highp mat4 kzProjectionCameraWorldMatrix;
varying mediump vec2 vTexCoord;
void main()
{
    
    
    precision mediump float;
    vTexCoord = kzTextureCoordinate0;
    gl_Position = kzProjectionCameraWorldMatrix * vec4(kzPosition.xyz, 1.0);
}

 
 
  
  

 
 
  
  

Fragment shader:

uniform sampler2D Texture;
varying mediump vec2 vTexCoord;
uniform lowp float BlendIntensity;
uniform lowp float Radius;
uniform lowp float RadiusWidth;

void main()
{
    
    
    precision mediump float；
    vec4  color = vec4(0.0); 
    vec4  outcolor = vec4(0.0); 
    vec4  colorTT = texture2D(Texture, vTexCoord);
    
    vec2 pos = vTexCoord *2.0-1.0;  //圆心
    float dis = length(pos);  //半径
    if(dis < Radius)
    {
    
    
//小于Radius-0.1返回0，大于Radiu返回1，Radius-0.1到Radius取平滑算法差值
        float offset  = smoothstep(Radius-0.1,Radius,dis);
//offset=0取colorTT，offset=1取color
//colorTT*(1-offset) + color*offset
        outcolor = mix(colorTT,color,offset);  
    }
    else
    {
    
    
        outcolor = vec4(0.0);   
    }       
    gl_FragColor.rgba = outcolor.rgba * BlendIntensity;
}

 
 
  
  

 
 
  
  

Writing materials in kanzi is a way for us to achieve cool effects. Basically, most of the simple effects in opengl can be realized in kanzi. The following is a picture that only shows the effect of a part of the picture, which is quite Yu dug a hole in the picture

Vertex shader :