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GPUImage自定義OpenGL ES着色器導致黑色圖像

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

 原文  2015-08-14 18:35:28  0   2    ios/ objective-c/ opengl-es/ gpuimage

問題描述

基於此，在另一個OpenGL ES圖像過濾器上工作： 

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));
}

根據昨天的問題 ，我知道為每個float和vec分配精度。 這一次，它編譯罰款，但是當我去申請在GPUImage過濾器（例如，通過設定的值clarity至0.8 ），圖像變黑。 我的直覺告訴我這與紋理大小有關，但是在不知道GPUImage如何處理紋理的情況下，我有點卡住了。

這是我在Objective-C中的實現：

。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應用GPUImage的內置低通和高通濾波器，但是我感覺最終將是一個笨拙的解決方案。

2 個解決方案

解決方案1
 1  2015-08-15 17:04:36

這可能是由於textureSize不是作為GPUImageFilter的一部分提供給您的標准統一。 inputImageTexture和textureCoordinate是這些過濾器之一提供的標准制服，看起來您正在提供clarity制服。

由於未設置textureSize ，因此默認值為0.0。 然后，您的1.0 / textureSize.x計算將被零除，這會導致iOS片段着色器中出現黑框。

您既可以計算並提供該制服，也可以查看將自定義過濾器基於GPUImage3x3TextureSamplingFilter。 該過濾器基類將1.0 / textureSize.x的結果作為texelWidth統一texelWidth （以及垂直組件的匹配texelHeight ）。 您不必計算這個。 實際上，它還會計算周圍8個像素的紋理坐標，因此您可以刪除上面的四個計算，並將其轉換為非依賴性紋理讀取。 您只需要基於2 * texelWidth和2 * texelHeight計算四個紋理讀取即可完成其余四個讀取。

實際上，您可能可以將該操作分為多次進行以節省計算，進行小盒子模糊處理，然后進行疊加混合，然后執行此過濾器的最后一個階段。 這樣可以進一步加快速度。

解決方案2
 0  2018-01-26 02:36:14

因此，您可以覆蓋 

(void)setupFilterForSize:(CGSize)filterFrameSize

設置寬度和高度因子的方法，例如GPUImageSharpenFilter 。

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