How to clear a colour from a sprite?

cocos2d-x C++
#1

I have a lot of images that has a black colour that should have been made transparent instead.
For example:

I want to clear the black colour and set it transparent with cocos2dx code instead of removing the colour with image editing tools. Mainly because I have thousands of images like that and to remove the colour for each image it would take a lot of time or perhaps someone knows a tool that can help achieve this easily? I have tried to use texture packer with heuristic mask option, but it only removes the corner from corners of the image.

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#2

Just don’t create such images. Use your source file of your art. For example .psd or .ai Or which format you are using? And export png’s without black layer.

#3

As I mentioned before: I have thousands of images like that and to remove the colour for each image it would take a lot of time.

How to achieve this by code?

#4

Sure, what a problem to edit your sources of art of these images? If it’s yours and you have source art files?

#5

the images are not mine, I’m just using them as testing purpose.

#6

Don’t steal.
And for removing color you probably should use a shaders, I know a very little about them…

#7

Never said anything about stealing. Just trying to remove colour from image by code.
It can be done by getting the image data and replacing pixels. But I don’t if its the best way to do that. Maybe using shaders would be better.

#8

I wrote a code to clear a black colour from sprite:

cocos2d::Sprite* SpriteResource::getSprite(string spriteName, bool mask)
{
auto img = new cocos2d::Image();
img->initWithImageFile(spriteName);

    if(mask)
    {
    const uint8_t * pixels = img->getData();
    unsigned int width = img->getWidth();
    unsigned int height = img->getHeight();
    
    // Create a new pixel buffer first for exception safety's sake
    std::vector<uint8_t> newPixels(pixels, pixels + width * height * 4);
    
    auto color = cocos2d::Color4B(0,0,0,255); //color to replace
    uint8_t alpha = 0; 
    
    uint8_t* ptr = &newPixels[0];
    uint8_t* end = ptr + newPixels.size();
    while (ptr < end)
    {
        if ((ptr[0] == color.r) && (ptr[1] == color.g) && (ptr[2] == color.b) && (ptr[3] == color.a))
            ptr[3] = alpha;
        ptr += 4;
    }

    auto text = new cocos2d::Texture2D();
    text->initWithData(newPixels.data(), sizeof(newPixels.data()), cocos2d::Texture2D::PixelFormat::RGBA8888, width, height, cocos2d::Size(width, height));
    return cocos2d::Sprite::createWithTexture(text);
    }

auto texture = new cocos2d::Texture2D();
texture->initWithImage(img);
return cocos2d::Sprite::createWithTexture(texture);
}
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#9

If you want to do it by shader then refer this post, someone helped me 2 year back :slight_smile:

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