glClear: clear buffers to preset values.

C Specification | Parameters | Description | Notes | Errors | Associated Gets | See Also

C Specification

void glClear(
    GLbitfield   mask)

Parameters

mask

Bitwise OR of masks that indicate the buffers to be cleared. The four masks are GL_COLOR_BUFFER_BIT, GL_DEPTH_BUFFER_BIT, GL_ACCUM_BUFFER_BIT, and GL_STENCIL_BUFFER_BIT.

Description

glClear sets the bitplane area of the window to values previously selected by glClearColor, glClearIndex, glClearDepth, glClearStencil, and glClearAccum. Multiple color buffers can be cleared simultaneously by selecting more than one buffer at a time using glDrawBuffer.

The pixel ownership test, the scissor test, dithering, and the buffer writemasks affect the operation of glClear. The scissor box bounds the cleared region. Alpha function, blend function, logical operation, stenciling, texture mapping, and depth-buffering are ignored by glClear.

glClear takes a single argument that is the bitwise or of several values indicating which buffer is to be cleared.

The values are as follows:

GL_COLOR_BUFFER_BIT

Indicates the buffers currently enabled for color writing.

GL_DEPTH_BUFFER_BIT

Indicates the depth buffer.

GL_ACCUM_BUFFER_BIT

Indicates the accumulation buffer.

GL_STENCIL_BUFFER_BIT

Indicates the stencil buffer.

The value to which each buffer is cleared depends on the setting of the clear value for that buffer.

Notes

If a buffer is not present, then a glClear directed at that buffer has no effect.

Errors

• GL_INVALID_VALUE is generated if any bit other than the four defined bits is set in mask.
• GL_INVALID_OPERATION is generated if glClear is executed between the execution of glBegin and the corresponding execution of glEnd.

glClearColor: specify clear values for the color buffers.

C Specification | Parameters | Description | Errors | Associated Gets | See Also

C Specification

void glClearColor(
    GLclampf     red,
    GLclampf     green,
    GLclampf     blue,
    GLclampf     alpha)

Parameters

red, green, blue, alpha

Specify the red, green, blue, and alpha values used when the color buffers are cleared. The initial values are all 0.

Description

glClearColor specifies the red, green, blue, and alpha values used by glClear to clear the color buffers. Values specified by glClearColor are clamped to the range [0, 1].

Errors

• GL_INVALID_OPERATION is generated if glClearColor is executed between the execution of glBegin and the corresponding execution of glEnd.

剛試了好久，現在整理出一些些心得首先你需要三個檔案：
glut.h
glut32.lib
glut32.dll

　　一般程式基本都要秀出訊息給使用者看，也因此，許多程式語言的第一堂課就是秀出一段訊息，「Hello, world!!」

這篇引言，其實滿不重要的。有基底的人就從下一篇開始看起吧！