SDI Technologies iH30 Especificações descarregar pdf (Página 70)

Advanced Topics

Quadro SDI Output PG-03776-001_v06 | 65

10.4.2 Multi-Sampling with Buffer Objects

An application that wishes to use multisampling with buffer objects will utilize the

capabilities enabled by the

GL_EXT_framebuffer_multisample OpenGL extension.

Unlike in the case of pbuffers, the application must perform the down sample bit and

filter operation prior to sending the buffer objects to the SDI device.

The first step is to create an additional multi-sampled buffer object during OpenGL

initialization. Frame buffer object creation is identical to that shown in Code Listing 8,

except for the specification of render buffer storage as demonstrated in Code Listing 46.

Code Listing 46: Requesting Multi-Sample Render Buffer Storage

if (num_samples > 1) {

glRenderbufferStorageMultisampleEXT(GL_RENDERBUFFER_EXT,

num_samples, texFormat,

width, height);

} else {

glRenderbufferStorageEXT(GL_RENDERBUFFER_EXT, texFormat,

width, height);

}

Then, in the draw loop, the Code Listing 47 performs the down sample and filter from

the multi-sample buffer object to the normal non-multi-sample buffer object prior to

presenting the final buffer object to the SDI video device.

Code Listing 47: Buffer Object Blit and Down Sample

// Bind buffer object

if (options.fsaa == 1)

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, gFBO);

else

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, gFBOMultiSampled)

glEnable(GL_MULTISAMPLE);

// Draw frame content here

if (options.fsaa == 1){

// Unbind FBO

glBindFramebufferEXT(GL_FRAMEBUFFER_EXT, 0);

} else {

// If using multisample render buffer,

// then blit to downsample and filter

glBindFramebufferEXT(GL_READ_FRAMEBUFFER_EXT,

gFBOMultiSampled);

glBindFramebufferEXT(GL_DRAW_FRAMEBUFFER_EXT,

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SDI Technologies iH30 Especificações Página 70