Name

glBindFramebuffer
繫結一個named framebuffer object。

C Specification

void glBindFramebuffer( GLenum target,
    GLuint framebuffer);

Parameters

target
指定framebuffer object要繫結的target。這個常量標識必須是GL_FRAMEBUFFER。

framebuffer
指定framebuffer object的名字。

Description

1.glBindFramebuffer讓你建立或使用一個named framebuffer object。呼叫glBindFramebuffer，把target設為GL_FRAMEBUFFER，把framebuffer設為the name of the new framebuffer object，將繫結這個framebuffer object name。當一個framebuffer object被繫結，之前的繫結將自動斷開。

2.Framebuffer object names是無符號整型。0值被保留，視窗系統用來提供預設framebuffer。Framebuffer object names和對應的framebuffer object contents被放置在當前GL rendering context的共享物件空間中。

3.You may use glGenFramebuffers to generate a set of new framebuffer object names.

4.當一個framebuffer object第一次被繫結時，它的3個關聯點(GL_COLOR_ATTACHMENT0, GL_DEPTH_ATTACHMENT, and GL_STENCIL_ATTACHMENT) 的狀態是GL_NONE。不太確定，上原文吧：The state of a framebuffer object immediately after it is first bound is three attachment points (GL_COLOR_ATTACHMENT0, GL_DEPTH_ATTACHMENT, and GL_STENCIL_ATTACHMENT) each with GL_NONE as the object type.

5.當一個非0的framebuffer object name被繫結，GL在target GL_FRAMEBUFFER的上的操作將影響繫結的framebuffer object，對target GL_FRAMEBUFFER的查詢，或者framebuffer的細節如GL_DEPTH_BITS（從繫結的framebuffer object返回的狀態）。當0值的framebuffer object name被繫結，作為初始狀態，企圖修改或查詢target GL_FRAMEBUFFER的狀態將會生成GL_INVALID_OPERATION錯誤。

6.當一個非零framebuffer object name被繫結，所有對這個framebuffer的渲染（with glDrawArrays and glDrawElements）和從這個framebuffer中讀（with glReadPixels, glCopyTexImage2D, or glCopyTexSubImage2D），將使用關聯到這個application-created framebuffer object的images，而不是預設的window-system-provided framebuffer.

7.應用程式建立的framebuffer objects不同於預設的視窗系統提供的framebuffer的幾個方面。第一，他們擁有可更改的關聯a color buffer, a depth buffer, and a stencil buffer的指向framebuffer attachable images的指標，這些images可以被attached and detached.第二，被關聯的images的大小和格式，可以被GL完全控制，且不會被window-system事件影響，比如畫素格式選擇，視窗大小重置，和改變顯示模式。第三，當對一個application created framebuffer object進行rendering to or reading，畫素擁有權測試一直是成功 (i.e. they own all their pixels)。第四，沒有可見的color buffer bitplanes，只有一個單一的”off-screen” color image attachment, 所以front and back buffers or swapping是沒有意義的。最後，這裡沒有多重取樣（multisample）buffer, 所以implementation-dependent state的值GL_SAMPLES and GL_SAMPLE_BUFFERS 都是0.

8.A framebuffer object binding created with glBindFramebuffer remains active until a different framebuffer object name is bound, or until the bound framebuffer object is deleted with glDeleteFramebuffers.

Notes

Queries of implementation-dependent pixel depths and related state are derived from the currently bound framebuffer object. These include GL_RED_BITS, GL_GREEN_BITS, GL_BLUE_BITS, GL_ALPHA_BITS, GL_DEPTH_BITS, GL_STENCIL_BITS, GL_IMPLEMENTATION_COLOR_READ_TYPE, GL_IMPLEMENTATION_COLOR_READ_FORMAT, GL_SAMPLES, and GL_SAMPLE_BUFFERS.