Not implemented OpenGL methods:

glAreTexturesResident glBitmap glBlendColorEXT glCallLists glColorPointer glDeleteTextures glDrawElements glEdgeFlagPointer glEdgeFlagv glEvalMesh glFeedbackBuffer glGenTextures glGetBooleanv glGetClipPlane glGetDoublev glGetFloatv glGetIntegerv glGetLight glGetMap glGetMaterial glGetPixelMap glGetPointerv glGetPolygonStipple glGetTexEnv glGetTexGen glGetTexImage glGetTexLevelParameter glGetTexParameter glIndexPointer glInterleavedArrays glMap1 glMap2 glMapGrid glNormalPointer glPixelMap glPixelStore glPixelTransfer glPolygonStipple glPrioritizeTextures glReadPixels glRect glSelectBuffer glTexCoordPointer glTexImage1D glTexSubImage1D glVertexPointer

The accumulation buffer is an extended-range color buffer. Images are not rendered into it. Rather, images rendered into one of the color buffers are added to the contents of the accumulation buffer after rendering. Effects such as antialiasing (of points, lines, and polygons), motion blur, and depth of field can be created by accumulating images generated with different transformation matrices.

Each pixel in the accumulation buffer consists of red, green, blue, and alpha values. The number of bits per component in the accumulation buffer depends on the implementation. You can examine this number by calling glGetIntegerv four times, with arguments GL_ACCUM_RED_BITS , GL_ACCUM_GREEN_BITS , GL_ACCUM_BLUE_BITS , and GL_ACCUM_ALPHA_BITS . Regardless of the number of bits per component, the range of values stored by each component is [-1, 1]. The accumulation buffer pixels are mapped one-to-one with frame buffer pixels.

glAccum operates on the accumulation buffer. The first argument, op, is a symbolic constant that selects an accumulation buffer operation. The second argument, value, is a floating-point value to be used in that operation. Five operations are specified: GL_ACCUM , GL_LOAD , GL_ADD , GL_MULT , and GL_RETURN .

All accumulation buffer operations are limited to the area of the current scissor box and applied identically to the red, green, blue, and alpha components of each pixel. If a glAccum operation results in a value outside the range [-1, 1], the contents of an accumulation buffer pixel component are undefined.

The operations are as follows:

GL_ACCUM Obtains R, G, B, and A values from the buffer currently selected for reading (see glReadBuffer ). Each component value is divided by 2n1, where n is the number of bits allocated to each color component in the currently selected buffer. The result is a floating-point value in the range [0, 1], which is multiplied by value and added to the corresponding pixel component in the accumulation buffer, thereby updating the accumulation buffer. GL_LOAD Similar to GL_ACCUM , except that the current value in the accumulation buffer is not used in the calculation of the new value. That is, the R, G, B, and A values from the currently selected buffer are divided by 2n1, multiplied by value, and then stored in the corresponding accumulation buffer cell, overwriting the current value. GL_ADD Adds value to each R, G, B, and A in the accumulation buffer. GL_MULT Multiplies each R, G, B, and A in the accumulation buffer by value and returns the scaled component to its corresponding accumulation buffer location. GL_RETURN Transfers accumulation buffer values to the color buffer or buffers currently selected for writing. Each R, G, B, and A component is multiplied by value, then multiplied by 2n1, clamped to the range [0, 2n1 ], and stored in the corresponding display buffer cell. The only fragment operations that are applied to this transfer are pixel ownership, scissor, dithering, and color writemasks.

To clear the accumulation buffer, call glClearAccum with R, G, B, and A values to set it to, then call glClear with the accumulation buffer enabled.

Specifies the accumulation buffer operation. Symbolic constants GL_ACCUM , GL_LOAD , GL_ADD , GL_MULT , and GL_RETURN are accepted.

Specifies a floating-point value used in the accumulation buffer operation. op determines how value is used.

GL_INVALID_ENUM is generated if op is not an accepted value.

GL_INVALID_OPERATION is generated if there is no accumulation buffer.

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

The alpha test discards fragments depending on the outcome of a comparison between an incoming fragment's alpha value and a constant reference value. glAlphaFunc specifies the reference value and the comparison function. The comparison is performed only if alpha testing is enabled. By default, it is not enabled. (See glEnable and glDisable of GL_ALPHA_TEST .)

func and ref specify the conditions under which the pixel is drawn. The incoming alpha value is compared to ref using the function specified by func. If the value passes the comparison, the incoming fragment is drawn if it also passes subsequent stencil and depth buffer tests. If the value fails the comparison, no change is made to the frame buffer at that pixel location. The comparison functions are as follows:

GL_NEVER Never passes. GL_LESS Passes if the incoming alpha value is less than the reference value. GL_EQUAL Passes if the incoming alpha value is equal to the reference value. GL_LEQUAL Passes if the incoming alpha value is less than or equal to the reference value. GL_GREATER Passes if the incoming alpha value is greater than the reference value. GL_NOTEQUAL Passes if the incoming alpha value is not equal to the reference value. GL_GEQUAL Passes if the incoming alpha value is greater than or equal to the reference value. GL_ALWAYS Always passes (initial value).

glAlphaFunc operates on all pixel write operations, including those resulting from the scan conversion of points, lines, polygons, and bitmaps, and from pixel draw and copy operations. glAlphaFunc does not affect screen clear operations.

Specifies the alpha comparison function. Symbolic constants GL_NEVER , GL_LESS , GL_EQUAL , GL_LEQUAL , GL_GREATER , GL_NOTEQUAL , GL_GEQUAL , and GL_ALWAYS are accepted. The initial value is GL_ALWAYS .

Specifies the reference value that incoming alpha values are compared to. This value is clamped to the range 0 through 1, where 0 represents the lowest possible alpha value and 1 the highest possible value. The initial reference value is 0.

GL_INVALID_ENUM is generated if func is not an accepted value.

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

glArrayElement commands are used within glBegin /glEnd pairs to specify vertex and attribute data for point, line, and polygon primitives. If GL_VERTEX_ARRAY is enabled when glArrayElement is called, a single vertex is drawn, using vertex and attribute data taken from location i of the enabled arrays. If GL_VERTEX_ARRAY is not enabled, no drawing occurs but the attributes corresponding to the enabled arrays are modified.

Use glArrayElement to construct primitives by indexing vertex data, rather than by streaming through arrays of data in first-to-last order. Because each call specifies only a single vertex, it is possible to explicitly specify per-primitive attributes such as a single normal per individual triangle.

Changes made to array data between the execution of glBegin and the corresponding execution of glEnd may affect calls to glArrayElement that are made within the same glBegin /glEnd period in non-sequential ways. That is, a call to

glArrayElement that precedes a change to array data may access the changed data, and a call that follows a change to array data may access original data.

Specifies an index into the enabled vertex data arrays.

glBindTexture lets you create or use a named texture. Calling glBindTexture with

target set to GL_TEXTURE_1D or GL_TEXTURE_2D and texture set to the name of the newtexture binds the texture name to the target. When a texture is bound to a target, the previous binding for that target is automatically broken.

Texture names are unsigned integers. The value zero is reserved to represent the default texture for each texture target. Texture names and the corresponding texture contents are local to the shared display-list space (see glXCreateContext ) of the current GL rendering context; two rendering contexts share texture names only if they also share display lists.

You may use glGenTextures to generate a set of new texture names.

When a texture is first bound, it assumes the dimensionality of its target: A texture first bound to GL_TEXTURE_1D becomes 1-dimensional and a texture first bound to GL_TEXTURE_2D becomes 2-dimensional. The state of a 1-dimensional texture immediately after it is first bound is equivalent to the state of the default GL_TEXTURE_1D at GL initialization, and similarly for 2-dimensional textures.

While a texture is bound, GL operations on the target to which it is bound affect the bound texture, and queries of the target to which it is bound return state from the bound texture. If texture mapping of the dimensionality of the target to which a texture is bound is active, the bound texture is used. In effect, the texture targets become aliases for the textures currently bound to them, and the texture name zero refers to the default textures that were bound to them at initialization.

A texture binding created with glBindTexture remains active until a different texture is bound to the same target, or until the bound texture is deleted with glDeleteTextures .

Once created, a named texture may be re-bound to the target of the matching dimensionality as often as needed. It is usually much faster to use glBindTexture to bind an existing named texture to one of the texture targets than it is to reload the texture image using glTexImage1D or glTexImage2D . For additional control over performance, use glPrioritizeTextures .

glBindTexture is included in display lists.

Specifies the target to which the texture is bound. Must be either GL_TEXTURE_1D or GL_TEXTURE_2D .

Specifies the name of a texture.

GL_INVALID_ENUM is generated if target is not one of the allowable values.

GL_INVALID_OPERATION is generated if texture has a dimensionality which doesn't match that of target.

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

In RGBA mode, pixels can be drawn using a function that blends the incoming (source) RGBA values with the RGBA values that are already in the frame buffer (the destination values). Blending is initially disabled. Use glEnable and glDisable with argument GL_BLEND to enable and disable blending.

glBlendFunc defines the operation of blending when it is enabled. sfactor specifies which of nine methods is used to scale the source color components. dfactor specifies which of eight methods is used to scale the destination color components. The eleven possible methods are described in the following table. Each method defines four scale factors, one each for red, green, blue, and alpha.

In the table and in subsequent equations, source and destination color components are referred to as (R sub s , G sub s , B sub s , A sub s ) and (R sub d , G sub d , B sub d , A sub d ). They are understood to have integer values between 0 and (k sub R , k sub G , k sub B , k sub A ), where

.RS .ce k sub c ~=~ 2 sup m sub c - 1 .RE

and (m sub R , m sub G , m sub B , m sub A ) is the number of red, green, blue, and alpha bitplanes.

Source and destination scale factors are referred to as (s sub R , s sub G , s sub B , s sub A ) and (d sub R , d sub G , d sub B , d sub A ). The scale factors described in the table, denoted (f sub R , f sub G , f sub B , f sub A ), represent either source or destination factors. All scale factors have range [0,1].

.TS center box ; ci | ci c | c . parameter (f sub R , ~~ f sub G , ~~ f sub B , ~~ f sub A ) = GL_ZERO (0, ~0, ~0, ~0 ) GL_ONE (1, ~1, ~1, ~1 ) GL_SRC_COLOR (R sub s / k sub R , ~G sub s / k sub G , ~B sub s / k sub B , ~A sub s / k sub A ) GL_ONE_MINUS_SRC_COLOR (1, ~1, ~1, ~1 ) ~-~ (R sub s / k sub R , ~G sub s / k sub G , ~B sub s / k sub B , ~A sub s / k sub A ) GL_DST_COLOR (R sub d / k sub R , ~G sub d / k sub G , ~B sub d / k sub B , ~A sub d / k sub A ) GL_ONE_MINUS_DST_COLOR (1, ~1, ~1, ~1 ) ~-~ (R sub d / k sub R , ~G sub d / k sub G , ~B sub d / k sub B , ~A sub d / k sub A ) GL_SRC_ALPHA (A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A ) GL_ONE_MINUS_SRC_ALPHA (1, ~1, ~1, ~1 ) ~-~ (A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A , ~A sub s / k sub A ) GL_DST_ALPHA (A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A ) GL_ONE_MINUS_DST_ALPHA (1, ~1, ~1, ~1 ) ~-~ (A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A , ~A sub d / k sub A ) GL_SRC_ALPHA_SATURATE (i, ~i, ~i, ~1 ) .TE .sp In the table,

.RS .nf

i ~=~ min (A sub s , ~k sub A - A sub d ) ~/~ k sub A .fi .RE

To determine the blended RGBA values of a pixel when drawing in RGBA mode, the system uses the following equations:

.RS .nf

R sub d ~=~ min ( k sub R , ~~ R sub s s sub R + R sub d d sub R ) G sub d ~=~ min ( k sub G , ~~ G sub s s sub G + G sub d d sub G ) B sub d ~=~ min ( k sub B , ~~ B sub s s sub B + B sub d d sub B ) A sub d ~=~ min ( k sub A , ~~ A sub s s sub A + A sub d d sub A ) .fi .RE

Despite the apparent precision of the above equations, blending arithmetic is not exactly specified, because blending operates with imprecise integer color values. However, a blend factor that should be equal to 1 is guaranteed not to modify its multiplicand, and a blend factor equal to 0 reduces its multiplicand to 0. For example, when sfactor is GL_SRC_ALPHA , dfactor is GL_ONE_MINUS_SRC_ALPHA , and A sub s is equal to k sub A, the equations reduce to simple replacement:

.RS .nf

R sub d ~=~ R sub s G sub d ~=~ G sub s B sub d ~=~ B sub s A sub d ~=~ A sub s .fi .RE

Specifies how the red, green, blue, and alpha source blending factors are computed. Nine symbolic constants are accepted: GL_ZERO , GL_ONE , GL_DST_COLOR , GL_ONE_MINUS_DST_COLOR , GL_SRC_ALPHA , GL_ONE_MINUS_SRC_ALPHA , GL_DST_ALPHA , GL_ONE_MINUS_DST_ALPHA , and GL_SRC_ALPHA_SATURATE . The initial value is GL_ONE .

Specifies how the red, green, blue, and alpha destination blending factors are computed. Eight symbolic constants are accepted: GL_ZERO , GL_ONE , GL_SRC_COLOR , GL_ONE_MINUS_SRC_COLOR , GL_SRC_ALPHA , GL_ONE_MINUS_SRC_ALPHA , GL_DST_ALPHA , and GL_ONE_MINUS_DST_ALPHA . The initial value is GL_ZERO .

GL_INVALID_ENUM is generated if either sfactor or dfactor is not an accepted value.

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

glCallList causes the named display list to be executed. The commands saved in the display list are executed in order, just as if they were called without using a display list. If list has not been defined as a display list, glCallList is ignored.

glCallList can appear inside a display list. To avoid the possibility of infinite recursion resulting from display lists calling one another, a limit is placed on the nesting level of display lists during display-list execution. This limit is at least 64, and it depends on the implementation.

GL state is not saved and restored across a call to glCallList . Thus, changes made to GL state during the execution of a display list remain after execution of the display list is completed. Use glPushAttrib , glPopAttrib , glPushMatrix , and glPopMatrix to preserve GL state across glCallList calls.

Specifies the integer name of the display list to be executed.

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.

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 .

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 .

glClearAccum specifies the red, green, blue, and alpha values used by glClear to clear the accumulation buffer.

Values specified by glClearAccum are clamped to the range [-1,1].

Specify the red, green, blue, and alpha values used when the accumulation buffer is cleared. The initial values are all 0.

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

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].

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

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

glClearDepth specifies the depth value used by glClear to clear the depth buffer. Values specified by glClearDepth are clamped to the range [0,1].

Specifies the depth value used when the depth buffer is cleared. The initial value is 1.

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

glClearIndex specifies the index used by glClear to clear the color index buffers. c is not clamped. Rather, c is converted to a fixed-point value with unspecified precision to the right of the binary point. The integer part of this value is then masked with 2 sup m -1, where m is the number of bits in a color index stored in the frame buffer.

Specifies the index used when the color index buffers are cleared. The initial value is 0.

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