Messages

1

Graphics / Re: Use SFML in a video processing pipeline - use offscreen buffer

« on: October 11, 2021, 04:32:50 pm »

There is a comparison of direct OpenGL methods here - https://stackoverflow.com/questions/68791782/fastest-way-to-transfer-buffer-texture-data-from-gpu-to-cpu

1)Using glReadPixels - < 3.1ms

   glBindTexture(GL_TEXTURE_2D,depthTexture);
   glReadPixels(0, 0, width, height, GL_DEPTH_COMPONENT, GL_FLOAT,mat.data);
 

2)Using glGetTexImage - <2.9ms

glBindTexture(GL_TEXTURE_2D,depthTexture);
glGetTexImage(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, GL_FLOAT, mat.data);
 

3)Using PBO with glGetTexImage - <2.3ms

glBindBuffer(GL_PIXEL_PACK_BUFFER, pbo);
glBindTexture(GL_TEXTURE_2D, depthTexture);
glGetTexImage(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, GL_FLOAT, 0);
mat.data = (uchar*)glMapBuffer(GL_PIXEL_PACK_BUFFER, GL_READ_ONLY);
 

2

Graphics / Re: Use SFML in a video processing pipeline - use offscreen buffer

« on: October 11, 2021, 04:04:32 pm »

Thats an image buffer of

uint8_t * pixels

a. Copy image buffer to Texture
 

void sf::Texture::update        (       const Uint8 *   pixels  )

b. Render using SFML to texture

c. Copy sf::Texture to sf::Image

or
a. Use sf::Image with you buffer copied to sf::Image
b. Copy sf::Image to sf::Texture
c. Copy sf::Texture to sf::Image


Are these the two options you described ?

3

Graphics / Use SFML in a video processing pipeline - use offscreen buffer

« on: October 08, 2021, 01:51:25 pm »

In my application, I originally obtain an image buffer on the CPU. This is then copied over to SFML - processed with overlays, and then copied back to CPU image buffer.
I looked at sf::Image and sf::RenderTexture. If I understand this correctly, I need to
a. Copy CPU Image Buffer to sf::Image
b. Copy sf::Image to sf::RenderTexture
c. Process overlays in sf::RenderTexture
d. Copy sf::RenderTexture to sf::Image
e. Copy sf::Image to CPU Image Buffer

Does this sound correct ? Is there a sample code for someone using SFML in an image processing pipeline ?