Graphics Reference
In-Depth Information
from each buffer created in the first pass. As the depth testing has been
performed on the first pass, we will perform only one lighting calculation
per pixel.
The following steps show how to set up MRTs:
1. Initialize framebuffer objects (FBOs) using
glGenFramebuffers
and
glBindFramebuffer
commands (described in more detail in
Chapter 12, “Framebuffer Objects”) as shown here:
glGenFramebuffers ( 1, &fbo );
glBindFramebuffer ( GL_FRAMEBUFFER, fbo );
2.
Initialize textures using
glGenTextures
and
glBindTexture
commands
(described in more detail in Chapter 9, “Texturing”) as shown here:
glBindTexture ( GL_TEXTURE_2D, textureId );
glTexImage2D ( GL_TEXTURE_2D, 0, GL_RGBA,
textureWidth, textureHeight,
0, GL_RGBA, GL_UNSIGNED_BYTE, NULL );
// Set the filtering mode
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER,
GL_NEAREST );
glTexParameteri ( GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER,
GL_NEAREST );
3. Bind relevant textures to the FBO using
glFramebufferTexture2D
or
glFramebufferTextureLayer
command (described in more detail in
Chapter 12) as shown here:
glFramebufferTexture2D ( GL_DRAW_FRAMEBUFFER,
GL_COLOR_ATTACHMENT0,
GL_TEXTURE_2D,
textureId, 0 );
4. Specify color attachments for rendering using the following
glDrawBuffers
command:
void
glDrawBuffers
(GLsizei
n
,
const
GLenum*
bufs
)
specifies the number of buffers in
bufs
n
points to an array of symbolic constants specifying the
buffers into which fragment colors or data values will be
written
bufs
