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<HTML><BODY><PRE> <STRONG>NAME</STRONG> <STRONG>fgluBuild1DMipmaps</STRONG> - builds a 1-D mipmap <STRONG>FORTRAN</STRONG> <STRONG>SPECIFICATION</STRONG> INTEGER*4 <STRONG>fgluBuild1DMipmaps</STRONG>( INTEGER*4 <EM>target</EM>, INTEGER*4 <EM>internalFormat</EM>, INTEGER*4 <EM>width</EM>, INTEGER*4 <EM>format</EM>, INTEGER*4 <EM>type</EM>, void <EM>data</EM> ) <STRONG>PARAMETERS</STRONG> <EM>target</EM> Specifies the target texture. Must be <STRONG>GL_TEXTURE_1D</STRONG>. <EM>internalFormat</EM> Requests the internal storage format of the texture image. Must be 1, 2, 3, or 4 or one of the following symbolic constants: <STRONG>GL_ALPHA</STRONG>, <STRONG>GL_ALPHA4</STRONG>, <STRONG>GL_ALPHA8</STRONG>, <STRONG>GL_ALPHA12</STRONG>, <STRONG>GL_ALPHA16</STRONG>, <STRONG>GL_LUMINANCE</STRONG>, <STRONG>GL_LUMINANCE4</STRONG>, <STRONG>GL_LUMINANCE8</STRONG>, <STRONG>GL_LUMINANCE12</STRONG>, <STRONG>GL_LUMINANCE16</STRONG>, <STRONG>GL_LUMINANCE_ALPHA</STRONG>, <STRONG>GL_LUMINANCE4_ALPHA4</STRONG>, <STRONG>GL_LUMINANCE6_ALPHA2</STRONG>, <STRONG>GL_LUMINANCE8_ALPHA8</STRONG>, <STRONG>GL_LUMINANCE12_ALPHA4</STRONG>, <STRONG>GL_LUMINANCE12_ALPHA12</STRONG>, <STRONG>GL_LUMINANCE16_ALPHA16</STRONG>, <STRONG>GL_INTENSITY</STRONG>, <STRONG>GL_INTENSITY4</STRONG>, <STRONG>GL_INTENSITY8</STRONG>, <STRONG>GL_INTENSITY12</STRONG>, <STRONG>GL_INTENSITY16</STRONG>, <STRONG>GL_RGB</STRONG>, <STRONG>GL_R3_G3_B2</STRONG>, <STRONG>GL_RGB4</STRONG>, <STRONG>GL_RGB5</STRONG>, <STRONG>GL_RGB8</STRONG>, <STRONG>GL_RGB10</STRONG>, <STRONG>GL_RGB12</STRONG>, <STRONG>GL_RGB16</STRONG>, <STRONG>GL_RGBA</STRONG>, <STRONG>GL_RGBA2</STRONG>, <STRONG>GL_RGBA4</STRONG>, <STRONG>GL_RGB5_A1</STRONG>, <STRONG>GL_RGBA8</STRONG>, <STRONG>GL_RGB10_A2</STRONG>, <STRONG>GL_RGBA12</STRONG> or <STRONG>GL_RGBA16</STRONG>. <EM>width</EM> Specifies the width, in pixels, of the texture image. <EM>format</EM> Specifies the format of the pixel data. Must be one of <STRONG>GL_COLOR_INDEX</STRONG>, <STRONG>GL_RED</STRONG>, <STRONG>GL_GREEN</STRONG>, <STRONG>GL_BLUE</STRONG>, <STRONG>GL_ALPHA</STRONG>, <STRONG>GL_RGB</STRONG>, <STRONG>GL_RGBA</STRONG>, <STRONG>GL_LUMINANCE</STRONG>, and <STRONG>GL_LUMINANCE_ALPHA</STRONG>. <EM>type</EM> Specifies the data type for <EM>data</EM>. Must be one of <STRONG>GL_UNSIGNED_BYTE</STRONG>, <STRONG>GL_BYTE</STRONG>, <STRONG>GL_BITMAP</STRONG>, <STRONG>GL_UNSIGNED_SHORT</STRONG>, <STRONG>GL_SHORT</STRONG>, <STRONG>GL_UNSIGNED_INT</STRONG>, <STRONG>GL_INT</STRONG>, or <STRONG>GL_FLOAT</STRONG>. <EM>data</EM> Specifies a pointer to the image data in memory. <STRONG>DESCRIPTION</STRONG> <STRONG>fgluBuild1DMipmaps</STRONG> builds a series of prefiltered 1-D texture maps of decreasing resolutions called a mipmap. This is used for the antialiasing of texture mapped primitives. A return value of 0 indicates success, otherwise a GLU error code is returned (see <STRONG>fgluErrorString</STRONG>). Initially, the <EM>width</EM> of <EM>data</EM> is checked to see if it is a power of two. If not, a copy of <EM>data</EM> (not <EM>data</EM>) is scaled up or down to the nearest power of two. This copy will be used for subsequent mipmapping operations described below. (If <EM>width</EM> is exactly between powers of 2, then the copy of <EM>data</EM> will scale upwards.) For example, if <EM>width</EM> is 57 then a copy of <EM>data</EM> will scale up to 64 before mipmapping takes place. Then, proxy textures (see <STRONG>glTexImage1D</STRONG>) are used to determine if the implementation can fit the requested texture. If not, <EM>width</EM> is continually halved until it fits. Next, a series of mipmap levels is built by decimating a copy of <EM>data</EM> in half until size 1 is reached. At each level, each texel in the halved mipmap level is an average of the corresponding two texels in the larger mipmap level. <STRONG>glTexImage1D</STRONG> is called to load each of these mipmap levels. Level 0 is a copy of <EM>data</EM>. The highest level is log2(width). For example, if width is 64 and the implementation can store a texture of this size, the following mipmap levels are built: 64x1, 32x1, 16x1, 8x1, 4x1, 2x1 and 1x1. These correspond to levels 0 through 6, respectively. See the <STRONG>glTexImage1D</STRONG> reference page for a description of the acceptable values for <EM>type</EM>. See the <STRONG>glDrawPixels</STRONG> reference page for a description of the acceptable values for <EM>data</EM>. <STRONG>NOTES</STRONG> Note that there is no direct way of querying the maximum level. This can be derived indirectly via <STRONG>glGetTexLevelParameter</STRONG>. First, query for the width actually used at level 0. (The width may not be equal to <EM>width</EM> since proxy textures might have scaled it to fit the implementation.) Then the maximum level can be derived from the formula log2(width). <STRONG>ERRORS</STRONG> <STRONG>GLU_INVALID_VALUE</STRONG> is returned if <EM>width</EM> is < 1. <STRONG>GLU_INVALID_ENUM</STRONG> is returned if <EM>internalFormat</EM>, <EM>format</EM> or <EM>type</EM> are not legal. <STRONG>SEE</STRONG> <STRONG>ALSO</STRONG> <STRONG>glDrawPixels</STRONG>, <STRONG>glTexImage1D</STRONG>, <STRONG>glTexImage2D</STRONG>, <STRONG>fgluBuild2DMipmaps</STRONG>, <STRONG>fgluErrorString</STRONG>, <STRONG>fgluScaleImage</STRONG></PRE></BODY></HTML>⌨️ 快捷键说明
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