Update color data dynamically in cocos2d-x

Question

I want to create some effects in cocos2d-x by updating raw color data of sprite, does cocos2d-x supply any ways to do that?

Update: My buffer is 4-bytes (A-R-G-B) for each pixels, viewport dimensions are 640x480. So, the buffer has 640 * 480 * 4 = 1228800 bytes in length and I update its content frequently.

Answer 1

This solution regenerates the texture each time it is changed. Note: the texture in this code uses the format RGBA - not ARGB.

The data(/texel) array m_TextureData and the sprite are allocated only once but the Texture2D object has to be released and recreated every time which might be a performance issue.

Note: the class names are the new ones from Cocos2d-x 3.1.x. In the main loop there's an alternative part for 2.2.x users. To use that one you have to use also the old class names (like ccColor4B, CCTexture2D, CCSprite).

in header:

Color4B    *m_TextureData;
Texture2D    *m_Texture;
Sprite       *m_Sprite;

in implementation:

int w = 640; // width  of texture
int h = 480; // height of texture

m_TextureData = new Color4B[w * h];

set colors directly - e.g.:

Color4B white;
white.r = 255;
white.g = 255;
white.b = 255;
white.a = 255;
m_TextureData[i] = white; // i is an index running from 0 to w*h-1

use data to initialize texture:

CCSize contentSize;
contentSize.width  = w;
contentSize.height = h;

m_Texture = new Texture2D;
m_Texture->initWithData(m_TextureData, kCCTexture2DPixelFormat_RGBA8888, w, h, contentSize);

create a Sprite with this texture:

m_Sprite = Sprite::createWithTexture(m_Texture);
m_Sprite->retain();

add m_Sprite to your scene

in main loop:
to change color/texels of texture dynamically modify m_TextureData:

m_TextureData[i] = ...;

in Cocos2d-x 2.x:
In 2.2.x you actually have to release the old texture and create a new one:

m_Texture->release(); // make sure that ccGLDeleteTexture() is called internally to prevent memory leakage

m_Texture = new Texture2D;
m_Texture->initWithData(m_TextureData, kCCTexture2DPixelFormat_RGBA8888, w, h, contentSize);

m_Sprite->setTexture(m_Texture); // update sprite with new texture

in Cocos2d-x 3.1.x

m_Texture->updateWithData(m_TextureData, 0, 0, w, h);

Later, don't forget to clean up.
in destructor:

m_Sprite->release();
m_Texture->release();
delete [] m_TextureData;