IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter

/******************************************************************************************/
//@Author:猿说编程
//@Blog(个人博客地址): www.codersrc.com
//@File:IOS – OpenGL ES 设置图像锐化 GPUImageSharpenFilter
//@Time:2022/04/17 07:30
//@Motto:不积跬步无以至千里，不积小流无以成江海，程序人生的精彩需要坚持不懈地积累！
/******************************************************************************************/

NSString \*const kGPUImageSharpenVertexShaderString = SHADER_STRING
(
attribute vec4 position;
attribute vec4 inputTextureCoordinate;

uniform float imageWidthFactor;
uniform float imageHeightFactor;
uniform float sharpness;

varying vec2 textureCoordinate;
varying vec2 leftTextureCoordinate;
varying vec2 rightTextureCoordinate;
varying vec2 topTextureCoordinate;
varying vec2 bottomTextureCoordinate;

varying float centerMultiplier;
varying float edgeMultiplier;

void main()
{
gl_Position = position;

     vec2 widthStep = vec2(imageWidthFactor, 0.0);
     vec2 heightStep = vec2(0.0, imageHeightFactor);

     textureCoordinate = inputTextureCoordinate.xy;
     leftTextureCoordinate = inputTextureCoordinate.xy - widthStep;
     rightTextureCoordinate = inputTextureCoordinate.xy + widthStep;
     topTextureCoordinate = inputTextureCoordinate.xy + heightStep;
     bottomTextureCoordinate = inputTextureCoordinate.xy - heightStep;

     centerMultiplier = 1.0 + 4.0 * sharpness;
     edgeMultiplier = sharpness;

}
);

#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString \*const kGPUImageSharpenFragmentShaderString = SHADER_STRING
(
precision highp float;

varying highp vec2 textureCoordinate;
varying highp vec2 leftTextureCoordinate;
varying highp vec2 rightTextureCoordinate;
varying highp vec2 topTextureCoordinate;
varying highp vec2 bottomTextureCoordinate;

varying highp float centerMultiplier;
varying highp float edgeMultiplier;

uniform sampler2D inputImageTexture;

void main()
{
mediump vec3 textureColor = texture2D(inputImageTexture, textureCoordinate).rgb;
mediump vec3 leftTextureColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;
mediump vec3 rightTextureColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;
mediump vec3 topTextureColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;
mediump vec3 bottomTextureColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;

     gl_FragColor = vec4((textureColor * centerMultiplier - (leftTextureColor * edgeMultiplier + rightTextureColor * edgeMultiplier + topTextureColor * edgeMultiplier + bottomTextureColor * edgeMultiplier)), texture2D(inputImageTexture, bottomTextureCoordinate).w);

}
);
#else
NSString \*const kGPUImageSharpenFragmentShaderString = SHADER_STRING
(
varying vec2 textureCoordinate;
varying vec2 leftTextureCoordinate;
varying vec2 rightTextureCoordinate;
varying vec2 topTextureCoordinate;
varying vec2 bottomTextureCoordinate;

varying float centerMultiplier;
varying float edgeMultiplier;

uniform sampler2D inputImageTexture;

void main()
{
vec3 textureColor = texture2D(inputImageTexture, textureCoordinate).rgb;
vec3 leftTextureColor = texture2D(inputImageTexture, leftTextureCoordinate).rgb;
vec3 rightTextureColor = texture2D(inputImageTexture, rightTextureCoordinate).rgb;
vec3 topTextureColor = texture2D(inputImageTexture, topTextureCoordinate).rgb;
vec3 bottomTextureColor = texture2D(inputImageTexture, bottomTextureCoordinate).rgb;

     gl_FragColor = vec4((textureColor * centerMultiplier - (leftTextureColor * edgeMultiplier + rightTextureColor * edgeMultiplier + topTextureColor * edgeMultiplier + bottomTextureColor * edgeMultiplier)), texture2D(inputImageTexture, bottomTextureCoordinate).w);

}
);
#endif