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GPUImage自定义OpenGL ES着色器导致黑色图像

[英]GPUImage custom OpenGL ES shader resulting in black image

 原文  2015-08-14 18:35:28  2   2    ios/ objective-c/ opengl-es/ gpuimage

问题描述

基于此，在另一个OpenGL ES图像过滤器上工作： 

uniform sampler2D texture;
uniform float amount;
uniform vec2 texSize;
varying vec2 texCoord;
void main() {
    vec4 color = texture2D(texture, texCoord);
    vec4 orig = color;

    /* High pass filter */
    vec4 highpass = color * 5.0;

    float dx = 1.0 / texSize.x;
    float dy = 1.0 / texSize.y;
    highpass += texture2D(texture, texCoord + vec2(-dx, -dy)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(dx, -dy)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(dx, dy)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(-dx, dy)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(-dx * 2.0, -dy * 2.0)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(dx * 2.0, -dy * 2.0)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(dx * 2.0, dy * 2.0)) * -0.625;
    highpass += texture2D(texture, texCoord + vec2(-dx * 2.0, dy * 2.0)) * -0.625;
    highpass.a = 1.0;

    /* Overlay blend */
    vec3 overlay = vec3(1.0);
    if (highpass.r <= 0.5) {
        overlay.r = 2.0 * color.r * highpass.r;
    } else {
        overlay.r = 1.0 - 2.0 * (1.0 - color.r) * (1.0 - highpass.r);
    }
    if (highpass.g <= 0.5) {
        overlay.g = 2.0 * color.g * highpass.g;
    } else {
        overlay.g = 1.0 - 2.0 * (1.0 - color.g) * (1.0 - highpass.g);
    }
    if (highpass.b <= 0.5) {
        overlay.b = 2.0 * color.b * highpass.b;
    } else {
        overlay.b = 1.0 - 2.0 * (1.0 - color.b) * (1.0 - highpass.b);
    }
    color.rgb = (overlay * 0.8) + (orig.rgb * 0.2);

    /* Desaturated hard light */
    vec3 desaturated = vec3(orig.r + orig.g + orig.b / 3.0);
    if (desaturated.r <= 0.5) {
        color.rgb = 2.0 * color.rgb * desaturated;
    } else {
        color.rgb = vec3(1.0) - vec3(2.0) * (vec3(1.0) - color.rgb) * (vec3(1.0) - desaturated);
    }
    color = (orig * 0.6) + (color * 0.4);

    /* Add back some color */
    float average = (color.r + color.g + color.b) / 3.0;
    color.rgb += (average - color.rgb) * (1.0 - 1.0 / (1.001 - 0.45));

    gl_FragColor = (color * amount) + (orig * (1.0 - amount));
}

根据昨天的问题 ，我知道为每个float和vec分配精度。 这一次，它编译罚款，但是当我去申请在GPUImage过滤器（例如，通过设定的值clarity至0.8 ），图像变黑。 我的直觉告诉我这与纹理大小有关，但是在不知道GPUImage如何处理纹理的情况下，我有点卡住了。

这是我在Objective-C中的实现：

。H 

#import <GPUImage/GPUImage.h>

@interface GPUImageClarityFilter : GPUImageFilter
{
    GLint clarityUniform;
}

// Gives the image a gritty, surreal contrasty effect
// Value 0 to 1
@property (readwrite, nonatomic) GLfloat clarity;

@end

.m 

#import "GPUImageClarityFilter.h"

#if TARGET_IPHONE_SIMULATOR || TARGET_OS_IPHONE
NSString *const kGPUImageClarityFragmentShaderString = SHADER_STRING
(
 uniform sampler2D inputImageTexture;
 uniform lowp float clarity;
 uniform highp vec2 textureSize;
 varying highp vec2 textureCoordinate;
 void main() {
     highp vec4 color = texture2D(inputImageTexture, textureCoordinate);
     highp vec4 orig = color;

     /* High pass filter */
     highp vec4 highpass = color * 5.0;

     highp float dx = 1.0 / textureSize.x;
     highp float dy = 1.0 / textureSize.y;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx, -dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx, -dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx, dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx, dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx * 2.0, -dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx * 2.0, -dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx * 2.0, dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx * 2.0, dy * 2.0)) * -0.625;
     highpass.a = 1.0;

     /* Overlay blend */
     highp vec3 overlay = vec3(1.0);
     if (highpass.r <= 0.5) {
         overlay.r = 2.0 * color.r * highpass.r;
     } else {
         overlay.r = 1.0 - 2.0 * (1.0 - color.r) * (1.0 - highpass.r);
     }
     if (highpass.g <= 0.5) {
         overlay.g = 2.0 * color.g * highpass.g;
     } else {
         overlay.g = 1.0 - 2.0 * (1.0 - color.g) * (1.0 - highpass.g);
     }
     if (highpass.b <= 0.5) {
         overlay.b = 2.0 * color.b * highpass.b;
     } else {
         overlay.b = 1.0 - 2.0 * (1.0 - color.b) * (1.0 - highpass.b);
     }
     color.rgb = (overlay * 0.8) + (orig.rgb * 0.2);

     /* Desaturated hard light */
     highp vec3 desaturated = vec3(orig.r + orig.g + orig.b / 3.0);
     if (desaturated.r <= 0.5) {
         color.rgb = 2.0 * color.rgb * desaturated;
     } else {
         color.rgb = vec3(1.0) - vec3(2.0) * (vec3(1.0) - color.rgb) * (vec3(1.0) - desaturated);
     }
     color = (orig * 0.6) + (color * 0.4);

     /* Add back some color */
     highp float average = (color.r + color.g + color.b) / 3.0;
     color.rgb += (average - color.rgb) * (1.0 - 1.0 / (1.001 - 0.45));

     gl_FragColor = (color * clarity) + (orig * (1.0 - clarity));
 }
);
#else
NSString *const kGPUImageClarityFragmentShaderString = SHADER_STRING
(
 uniform sampler2D inputImageTexture;
 uniform float clarity;
 uniform vec2 textureSize;
 varying vec2 textureCoordinate;
 void main() {
     vec4 color = texture2D(inputImageTexture, textureCoordinate);
     vec4 orig = color;

     /* High pass filter */
     vec4 highpass = color * 5.0;

     float dx = 1.0 / textureSize.x;
     float dy = 1.0 / textureSize.y;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx, -dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx, -dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx, dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx, dy)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx * 2.0, -dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx * 2.0, -dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(dx * 2.0, dy * 2.0)) * -0.625;
     highpass += texture2D(inputImageTexture, textureCoordinate + vec2(-dx * 2.0, dy * 2.0)) * -0.625;
     highpass.a = 1.0;

     /* Overlay blend */
     vec3 overlay = vec3(1.0);
     if (highpass.r <= 0.5) {
         overlay.r = 2.0 * color.r * highpass.r;
     } else {
         overlay.r = 1.0 - 2.0 * (1.0 - color.r) * (1.0 - highpass.r);
     }
     if (highpass.g <= 0.5) {
         overlay.g = 2.0 * color.g * highpass.g;
     } else {
         overlay.g = 1.0 - 2.0 * (1.0 - color.g) * (1.0 - highpass.g);
     }
     if (highpass.b <= 0.5) {
         overlay.b = 2.0 * color.b * highpass.b;
     } else {
         overlay.b = 1.0 - 2.0 * (1.0 - color.b) * (1.0 - highpass.b);
     }
     color.rgb = (overlay * 0.8) + (orig.rgb * 0.2);

     /* Desaturated hard light */
     vec3 desaturated = vec3(orig.r + orig.g + orig.b / 3.0);
     if (desaturated.r <= 0.5) {
         color.rgb = 2.0 * color.rgb * desaturated;
     } else {
         color.rgb = vec3(1.0) - vec3(2.0) * (vec3(1.0) - color.rgb) * (vec3(1.0) - desaturated);
     }
     color = (orig * 0.6) + (color * 0.4);

     /* Add back some color */
     float average = (color.r + color.g + color.b) / 3.0;
     color.rgb += (average - color.rgb) * (1.0 - 1.0 / (1.001 - 0.45));

     gl_FragColor = (color * clarity) + (orig * (1.0 - clarity));
 }
);
#endif

@implementation GPUImageClarityFilter

@synthesize clarity = _clarity;

#pragma mark -
#pragma mark Initialization and teardown

- (id)init;
{
    if (!(self = [super initWithFragmentShaderFromString:kGPUImageClarityFragmentShaderString]))
    {
        return nil;
    }

    clarityUniform = [filterProgram uniformIndex:@"clarity"];
    self.clarity = 0.0;

    return self;
}

#pragma mark -
#pragma mark Accessors

- (void)setClarity:(GLfloat)clarity;
{
    _clarity = clarity;

    [self setFloat:_clarity forUniform:clarityUniform program:filterProgram];
}

@end

我想做的另一件事是应用GPUImage的内置低通和高通滤波器，但是我感觉最终将是一个笨拙的解决方案。

2 个解决方案

解决方案1
 1  2015-08-15 17:04:36

这可能是由于textureSize不是作为GPUImageFilter的一部分提供给您的标准统一。 inputImageTexture和textureCoordinate是这些过滤器之一提供的标准制服，看起来您正在提供clarity制服。

由于未设置textureSize ，因此默认值为0.0。 然后，您的1.0 / textureSize.x计算将被零除，这会导致iOS片段着色器中出现黑框。

您既可以计算并提供该制服，也可以查看将自定义过滤器基于GPUImage3x3TextureSamplingFilter。 该过滤器基类将1.0 / textureSize.x的结果作为texelWidth统一texelWidth （以及垂直组件的匹配texelHeight ）。 您不必计算这个。 实际上，它还会计算周围8个像素的纹理坐标，因此您可以删除上面的四个计算，并将其转换为非依赖性纹理读取。 您只需要基于2 * texelWidth和2 * texelHeight计算四个纹理读取即可完成其余四个读取。

实际上，您可能可以将该操作分为多次进行以节省计算，进行小盒子模糊处理，然后进行叠加混合，然后执行此过滤器的最后一个阶段。 这样可以进一步加快速度。

解决方案2
 0  2018-01-26 02:36:14

因此，您可以覆盖 

(void)setupFilterForSize:(CGSize)filterFrameSize

设置宽度和高度因子的方法，例如GPUImageSharpenFilter 。

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