The OpenGL Shading Language Runtime Library for Legacy Target.

Sounds good :)

src/mesa/shader/slang_fragment_builtin.gc

@@ -0,0 +1,354 @@
+
+// 
+// TODO:
+// - implement texture1D, texture2D, texture3D, textureCube,
+// - implement shadow1D, shadow2D,
+// - implement dFdx, dFdy,
+// 
+
+// 
+// From Shader Spec, ver. 1.051
+// 
+// The output of the fragment shader goes on to be processed by the fixed function operations at
+// the back end of the OpenGL pipeline. Fragment shaders interface with the back end of the OpenGL
+// pipeline using the built-in variables gl_FragColor and gl_FragDepth, or by executing the discard
+// keyword.
+// 
+// These variables may be written more than once within a fragment shader. If so, the last value
+// assigned is the one used in the subsequent fixed function pipeline. The values written to these
+// variables may be read back after writing them. Reading from these variables before writing them
+// results in an undefined value. The fixed functionality computed depth for a fragment may be
+// obtained by reading gl_FragCoord.z, described below.
+// 
+// Writing to gl_FragColor specifies the fragment color that will be used by the subsequent fixed
+// functionality pipeline. If subsequent fixed functionality consumes fragment color and an
+// execution of a fragment shader does not write a value to gl_FragColor then the fragment color
+// consumed is undefined.
+// 
+// If the frame buffer is configured as a color index buffer then behavior is undefined when using
+// a fragment shader.
+// 
+// Writing to gl_FragDepth will establish the depth value for the fragment being processed. If
+// depth buffering is enabled, and a shader does not write gl_FragDepth, then the fixed function
+// value for depth will be used as the fragment’s depth value. If a shader statically assigns
+// a value to gl_FragDepth, and there is an execution path through the shader that does not set
+// gl_FragDepth, then the value of the fragment’s depth may be undefined for some executions of
+// the shader. That is, if a shader statically writes gl_FragDepth, then it is responsible for
+// always writing it. There is also no guarantee that a shader can compute the same depth value
+// as the fixed function value; an implementation will provide invariant results within shaders
+// computing depth with the same source-level expression, but invariance is not provided between
+// shaders and fixed functionality.
+// 
+// Writes to gl_FragColor and gl_FragDepth need not be clamped within a shader. The fixed
+// functionality pipeline following the fragment shader will clamp these values.
+// 
+// If a shader executes the discard keyword, the fragment is discarded, and the values of
+// gl_FragDepth and gl_FragColor become irrelevant.
+// 
+// The variable gl_FragCoord is available as a read-only variable from within fragment shaders
+// and it holds the window relative coordinates x, y, z, and 1/w values for the fragment. This
+// value is the result of the fixed functionality that interpolates primitives after vertex
+// processing to generate fragments. The z component is the depth value that would be used for
+// the fragment’s depth if a shader contained no writes to gl_FragDepth. This is useful for
+// invariance if a shader conditionally computes gl_FragDepth but otherwise wants the fixed
+// functionality fragment depth.
+// 
+// The fragment shader has access to the read-only built-in variable gl_FrontFacing whose value
+// is true if the fragment belongs to a front-facing primitive. One use of this is to emulate
+// two-sided lighting by selecting one of two colors calculated by the vertex shader.
+// 
+// The built-in variables that are accessible from a fragment shader are intrinsically given types
+// as follows:
+// 
+
+vec4 gl_FragCoord;
+bool gl_FrontFacing;
+vec4 gl_FragColor;
+float gl_FragDepth;
+
+// 
+// However, they do not behave like variables with no qualifier; their behavior is as described
+// above. These built-in variables have global scope.
+// 
+
+// 
+// Unlike user-defined varying variables, the built-in varying variables don’t have a strict
+// one-to-one correspondence between the vertex language and the fragment language. Two sets are
+// provided, one for each language. Their relationship is described below.
+// 
+// The following varying variables are available to read from in a fragment shader. The gl_Color
+// and gl_SecondaryColor names are the same names as attributes passed to the vertex shader.
+// However, there is no name conflict, because attributes are visible only in vertex shaders
+// and the following are only visible in a fragment shader.
+// 
+
+varying vec4 gl_Color;
+varying vec4 gl_SecondaryColor;
+varying vec4 gl_TexCoord[];                             // at most will be gl_MaxTextureCoordsARB
+varying float gl_FogFragCoord;
+
+// 
+// The values in gl_Color and gl_SecondaryColor will be derived automatically by the system from
+// gl_FrontColor, gl_BackColor, gl_FrontSecondaryColor, and gl_BackSecondaryColor based on which
+// face is visible. If fixed functionality is used for vertex processing, then gl_FogFragCoord will
+// either be the z-coordinate of the fragment in eye space, or the interpolation of the fog
+// coordinate, as described in section 3.10 of the OpenGL 1.4 Specification. The gl_TexCoord[]
+// values are the interpolated gl_TexCoord[] values from a vertex shader or the texture coordinates
+// of any fixed pipeline based vertex functionality.
+// 
+// Indices to the fragment shader gl_TexCoord array are as described above in the vertex shader
+// text.
+// 
+
+// 
+// The OpenGL Shading Language defines an assortment of built-in convenience functions for scalar
+// and vector operations. Many of these built-in functions can be used in more than one type
+// of shader, but some are intended to provide a direct mapping to hardware and so are available
+// only for a specific type of shader.
+// 
+// The built-in functions basically fall into three categories:
+// 
+// • They expose some necessary hardware functionality in a convenient way such as accessing
+//   a texture map. There is no way in the language for these functions to be emulated by a shader.
+// 
+// • They represent a trivial operation (clamp, mix, etc.) that is very simple for the user
+//   to write, but they are very common and may have direct hardware support. It is a very hard
+//   problem for the compiler to map expressions to complex assembler instructions.
+// 
+// • They represent an operation graphics hardware is likely to accelerate at some point. The
+//   trigonometry functions fall into this category.
+// 
+// Many of the functions are similar to the same named ones in common C libraries, but they support
+// vector input as well as the more traditional scalar input.
+// 
+// Applications should be encouraged to use the built-in functions rather than do the equivalent
+// computations in their own shader code since the built-in functions are assumed to be optimal
+// (e.g., perhaps supported directly in hardware).
+// 
+// User code can replace built-in functions with their own if they choose, by simply re-declaring
+// and defining the same name and argument list.
+// 
+
+// 
+// Texture Lookup Functions
+// 
+// Texture lookup functions are available to both vertex and fragment shaders. However, level
+// of detail is not computed by fixed functionality for vertex shaders, so there are some
+// differences in operation between vertex and fragment texture lookups. The functions in the table
+// below provide access to textures through samplers, as set up through the OpenGL API. Texture
+// properties such as size, pixel format, number of dimensions, filtering method, number of mip-map
+// levels, depth comparison, and so on are also defined by OpenGL API calls. Such properties are
+// taken into account as the texture is accessed via the built-in functions defined below.
+// 
+// If a non-shadow texture call is made to a sampler whose texture has depth comparisons enabled,
+// then results are undefined. If a shadow texture call is made to a sampler whose texture does not
+// have depth comparisions enabled, the results are also undefined.
+// 
+// In all functions below, the bias parameter is optional for fragment shaders. The bias parameter
+// is not accepted in a vertex shader. For a fragment shader, if bias is present, it is added to
+// the calculated level of detail prior to performing the texture access operation. If the bias
+// parameter is not provided, then the implementation automatically selects level of detail:
+// For a texture that is not mip-mapped, the texture is used directly. If it is mip-mapped and
+// running in a fragment shader, the LOD computed by the implementation is used to do the texture
+// lookup. If it is mip-mapped and running on the vertex shader, then the base texture is used.
+// 
+// The built-ins suffixed with “Lod” are allowed only in a vertex shader. For the “Lod” functions,
+// lod is directly used as the level of detail.
+// 
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 1D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate coord.s is divided by
+// the last component of coord.
+// 
+// XXX
+vec4 texture1D (sampler1D sampler, float coord, float bias) {
+    return vec4 (0.0);
+}
+vec4 texture1DProj (sampler1D sampler, vec2 coord, float bias) {
+    return texture1D (sampler, coord.s / coord.t, bias);
+}
+vec4 texture1DProj (sampler1D sampler, vec4 coord, float bias) {
+    return texture1D (sampler, coord.s / coord.q, bias);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 2D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate (coord.s, coord.t) is
+// divided by the last component of coord. The third component of coord is ignored for the vec4
+// coord variant.
+// 
+// XXX
+vec4 texture2D (sampler2D sampler, vec2 coord, float bias) {
+    return vec4 (0.0);
+}
+vec4 texture2DProj (sampler2D sampler, vec3 coord, float bias) {
+    return texture2D (sampler, vec2 (coord.s / coord.p, coord.t / coord.p), bias);
+}
+vec4 texture2DProj (sampler2D sampler, vec4 coord, float bias) {
+    return texture2D (sampler, vec2 (coord.s / coord.q, coord.s / coord.q), bias);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 3D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate is divided by coord.q.
+// 
+// XXX
+vec4 texture3D (sampler3D sampler, vec3 coord, float bias) {
+    return vec4 (0.0);
+}   
+vec4 texture3DProj (sampler3D sampler, vec4 coord, float bias) {
+    return texture3DProj (sampler, vec3 (coord.s / coord.q, coord.t / coord.q, coord.p / coord.q),
+        bias);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the cube map texture currently bound
+// to sampler. The direction of coord is used to select which face to do a 2-dimensional texture
+// lookup in, as described in section 3.8.6 in version 1.4 of the OpenGL specification.
+// 
+// XXX
+vec4 textureCube (samplerCube sampler, vec3 coord, float bias) {
+    return vec4 (0.0);
+}
+
+// 
+// Use texture coordinate coord to do a depth comparison lookup on the depth texture bound
+// to sampler, as described in section 3.8.14 of version 1.4 of the OpenGL specification. The 3rd
+// component of coord (coord.p) is used as the R value. The texture bound to sampler must be a
+// depth texture, or results are undefined. For the projective (“Proj”) version of each built-in,
+// the texture coordinate is divide by coord.q, giving a depth value R of coord.p/coord.q. The
+// second component of coord is ignored for the “1D” variants.
+// 
+// XXX
+vec4 shadow1D (sampler1DShadow sampler, vec3 coord, float bias) {
+    return vec4 (0.0);
+}
+// XXX
+vec4 shadow2D (sampler2DShadow sampler, vec3 coord, float bias) {
+    return vec4 (0.0);
+}
+vec4 shadow1DProj (sampler1DShadow sampler, vec4 coord, float bias) {
+    return shadow1D (sampler, vec3 (coord.s / coord.q, 0.0, coord.p / coord.q), bias);
+}
+vec4 shadow2DProj (sampler2DShadow sampler, vec4 coord, float bias) {
+    return shadow2D (sampler, vec3 (coord.s / coord.q, coord.t / coord.q, coord.p / coord.q), bias);
+}
+
+// 
+// Fragment processing functions are only available in shaders intended for use on the fragment
+// processor. Derivatives may be computationally expensive and/or numerically unstable. Therefore,
+// an OpenGL implementation may approximate the true derivatives by using a fast but not entirely
+// accurate derivative computation.
+// 
+// The expected behavior of a derivative is specified using forward/backward differencing.
+// 
+// Forward differencing:
+// 
+// F(x+dx) - F(x) ~ dFdx(x) * dx            1a
+// dFdx(x) ~ (F(x+dx) - F(x)) / dx          1b
+// 
+// Backward differencing:
+// 
+// F(x-dx) - F(x) ~ -dFdx(x) * dx           2a
+// dFdx(x) ~ (F(x) - F(x-dx)) / dx          2b
+// 
+// With single-sample rasterization, dx <= 1.0 in equations 1b and 2b. For multi-sample
+// rasterization, dx < 2.0 in equations 1b and 2b.
+// 
+// dFdy is approximated similarly, with y replacing x.
+// 
+// A GL implementation may use the above or other methods to perform the calculation, subject
+// to the following conditions:
+// 
+// 1) The method may use piecewise linear approximations. Such linear approximations imply that
+//    higher order derivatives, dFdx(dFdx(x)) and above, are undefined.
+// 
+// 2) The method may assume that the function evaluated is continuous. Therefore derivatives within
+//    the body of a non-uniform conditional are undefined.
+// 
+// 3) The method may differ per fragment, subject to the constraint that the method may vary by
+//    window coordinates, not screen coordinates. The invariance requirement described in section
+//    3.1 of the OpenGL 1.4 specification is relaxed for derivative calculations, because
+//    the method may be a function of fragment location.
+// 
+// Other properties that are desirable, but not required, are:
+// 
+// 4) Functions should be evaluated within the interior of a primitive (interpolated, not
+//    extrapolated).
+// 
+// 5) Functions for dFdx should be evaluated while holding y constant. Functions for dFdy should
+//    be evaluated while holding x constant. However, mixed higher order derivatives, like
+//    dFdx(dFdy(y)) and dFdy(dFdx(x)) are undefined.
+// 
+// In some implementations, varying degrees of derivative accuracy may be obtained by providing
+// GL hints (section 5.6 of the OpenGL 1.4 specification), allowing a user to make an image
+// quality versus speed tradeoff.
+// 
+
+// 
+// Returns the derivative in x using local differencing for the input argument p.
+// 
+// XXX
+float dFdx (float p) {
+    return 0.0;
+}
+// XXX
+vec2 dFdx (vec2 p) {
+    return vec2 (0.0);
+}
+// XXX
+vec3 dFdx (vec3 p) {
+    return vec3 (0.0);
+}
+// XXX
+vec4 dFdx (vec4 p) {
+    return vec4 (0.0);
+}
+
+// 
+// Returns the derivative in y using local differencing for the input argument p.
+// 
+// These two functions are commonly used to estimate the filter width used to anti-alias procedural
+// textures.We are assuming that the expression is being evaluated in parallel on a SIMD array so
+// that at any given point in time the value of the function is known at the grid points
+// represented by the SIMD array. Local differencing between SIMD array elements can therefore
+// be used to derive dFdx, dFdy, etc.
+// 
+// XXX
+float dFdy (float p) {
+    return 0.0;
+}
+// XXX
+vec2 dFdy (vec2 p) {
+    return vec2 (0.0);
+}
+// XXX
+vec3 dFdy (vec3 p) {
+    return vec3 (0.0);
+}
+// XXX
+vec4 dFdy (vec4 p) {
+    return vec4 (0.0);
+}
+
+// 
+// Returns the sum of the absolute derivative in x and y using local differencing for the input
+// argument p, i.e.:
+// 
+// return = abs (dFdx (p)) + abs (dFdy (p));
+// 
+
+float fwidth (float p) {
+    return abs (dFdx (p)) + abs (dFdy (p));
+}
+vec2 fwidth (vec2 p) {
+    return abs (dFdx (p)) + abs (dFdy (p));
+}
+vec3 fwidth (vec3 p) {
+    return abs (dFdx (p)) + abs (dFdy (p));
+}
+vec4 fwidth (vec4 p) {
+    return abs (dFdx (p)) + abs (dFdy (p));
+}
+

src/mesa/shader/slang_vertex_builtin.gc

@@ -0,0 +1,260 @@
+
+// 
+// TODO:
+// - what to do with ftransform? can it stay in the current form?
+// - implement texture1DLod, texture2DLod, texture3DLod, textureCubeLod,
+// - implement shadow1DLod, shadow2DLod,
+// 
+
+// 
+// From Shader Spec, ver. 1.051
+// 
+// Some OpenGL operations still continue to occur in fixed functionality in between the vertex
+// processor and the fragment processor. Other OpenGL operations continue to occur in fixed
+// functionality after the fragment processor. Shaders communicate with the fixed functionality
+// of OpenGL through the use of built-in variables.
+// 
+// The variable gl_Position is available only in the vertex language and is intended for writing
+// the homogeneous vertex position. All executions of a well-formed vertex shader must write
+// a value into this variable. It can be written at any time during shader execution. It may also
+// be read back by the shader after being written. This value will be used by primitive assembly,
+// clipping, culling, and other fixed functionality operations that operate on primitives after
+// vertex processing has occurred. Compilers may generate a diagnostic message if they detect
+// gl_Position is not written, or read before being written, but not all such cases are detectable.
+// Results are undefined if a vertex shader is executed and does not write gl_Position.
+// 
+// The variable gl_PointSize is available only in the vertex language and is intended for a vertex
+// shader to write the size of the point to be rasterized. It is measured in pixels.
+// 
+// The variable gl_ClipVertex is available only in the vertex language and provides a place for
+// vertex shaders to write the coordinate to be used with the user clipping planes. The user must
+// ensure the clip vertex and user clipping planes are defined in the same coordinate space. User
+// clip planes work properly only under linear transform. It is undefined what happens under
+// non-linear transform.
+// 
+// These built-in vertex shader variables for communicating with fixed functionality are
+// intrinsically declared with the following types:
+// 
+
+vec4 gl_Position;                                       // must be written to
+float gl_PointSize;                                     // may be written to
+vec4 gl_ClipVertex;                                     // may be written to
+
+// 
+// If gl_PointSize or gl_ClipVertex are not written to, their values are undefined. Any of these
+// variables can be read back by the shader after writing to them, to retrieve what was written.
+// Reading them before writing them results in undefined behavior. If they are written more than
+// once, it is the last value written that is consumed by the subsequent operations.
+// 
+// These built-in variables have global scope.
+// 
+
+// 
+// The following attribute names are built into the OpenGL vertex language and can be used from
+// within a vertex shader to access the current values of attributes declared by OpenGL. All page
+// numbers and notations are references to the OpenGL 1.4 specification.
+// 
+
+// 
+// Vertex Attributes, p. 19.
+// 
+
+attribute vec4 gl_Color;
+attribute vec4 gl_SecondaryColor;
+attribute vec3 gl_Normal;
+attribute vec4 gl_Vertex;
+attribute vec4 gl_MultiTexCoord0;
+attribute vec4 gl_MultiTexCoord1;
+attribute vec4 gl_MultiTexCoord2;
+attribute vec4 gl_MultiTexCoord3;
+attribute vec4 gl_MultiTexCoord4;
+attribute vec4 gl_MultiTexCoord5;
+attribute vec4 gl_MultiTexCoord6;
+attribute vec4 gl_MultiTexCoord7;
+attribute float gl_FogCoord;
+
+// 
+// Unlike user-defined varying variables, the built-in varying variables don’t have a strict
+// one-to-one correspondence between the vertex language and the fragment language. Two sets are
+// provided, one for each language. Their relationship is described below.
+// 
+// The following built-in varying variables are available to write to in a vertex shader.
+// A particular one should be written to if any functionality in a corresponding fragment shader
+// or fixed pipeline uses it or state derived from it. Otherwise, behavior is undefined.
+//
+
+varying vec4 gl_FrontColor;
+varying vec4 gl_BackColor;
+varying vec4 gl_FrontSecondaryColor;
+varying vec4 gl_BackSecondaryColor;
+varying vec4 gl_TexCoord[];                             // at most will be gl_MaxTextureCoordsARB
+varying float gl_FogFragCoord;
+
+// 
+// For gl_FogFragCoord, the value written will be used as the “c” value on page 160 of the
+// OpenGL 1.4 Specification by the fixed functionality pipeline. For example, if the z-coordinate
+// of the fragment in eye space is desired as “c”, then that's what the vertex shader should write
+// into gl_FogFragCoord.
+// 
+// As with all arrays, indices used to subscript gl_TexCoord must either be integral constant
+// expressions, or this array must be re-declared by the shader with a size. The size can be
+// at most gl_MaxTextureCoordsARB. Using indexes close to 0 may aid the implementation
+// in preserving varying resources.
+// 
+
+// 
+// The OpenGL Shading Language defines an assortment of built-in convenience functions for scalar
+// and vector operations. Many of these built-in functions can be used in more than one type
+// of shader, but some are intended to provide a direct mapping to hardware and so are available
+// only for a specific type of shader.
+// 
+// The built-in functions basically fall into three categories:
+// 
+// • They expose some necessary hardware functionality in a convenient way such as accessing
+//   a texture map. There is no way in the language for these functions to be emulated by a shader.
+// 
+// • They represent a trivial operation (clamp, mix, etc.) that is very simple for the user
+//   to write, but they are very common and may have direct hardware support. It is a very hard
+//   problem for the compiler to map expressions to complex assembler instructions.
+// 
+// • They represent an operation graphics hardware is likely to accelerate at some point. The
+//   trigonometry functions fall into this category.
+// 
+// Many of the functions are similar to the same named ones in common C libraries, but they support
+// vector input as well as the more traditional scalar input.
+// 
+// Applications should be encouraged to use the built-in functions rather than do the equivalent
+// computations in their own shader code since the built-in functions are assumed to be optimal
+// (e.g., perhaps supported directly in hardware).
+// 
+// User code can replace built-in functions with their own if they choose, by simply re-declaring
+// and defining the same name and argument list.
+// 
+
+// 
+// Geometric Functions
+// 
+// These operate on vectors as vectors, not component-wise.
+// 
+
+// 
+// For vertex shaders only. This function will ensure that the incoming vertex value will be
+// transformed in a way that produces exactly the same result as would be produced by OpenGL’s
+// fixed functionality transform. It is intended to be used to compute gl_Position, e.g.,
+// gl_Position = ftransform()
+// This function should be used, for example, when an application is rendering the same geometry in
+// separate passes, and one pass uses the fixed functionality path to render and another pass uses
+// programmable shaders.
+// 
+
+vec4 ftransform () {
+    return gl_ModelViewProjectionMatrix * gl_Vertex;
+}
+
+// 
+// Texture Lookup Functions
+// 
+// Texture lookup functions are available to both vertex and fragment shaders. However, level
+// of detail is not computed by fixed functionality for vertex shaders, so there are some
+// differences in operation between vertex and fragment texture lookups. The functions in the table
+// below provide access to textures through samplers, as set up through the OpenGL API. Texture
+// properties such as size, pixel format, number of dimensions, filtering method, number of mip-map
+// levels, depth comparison, and so on are also defined by OpenGL API calls. Such properties are
+// taken into account as the texture is accessed via the built-in functions defined below.
+// 
+// If a non-shadow texture call is made to a sampler whose texture has depth comparisons enabled,
+// then results are undefined. If a shadow texture call is made to a sampler whose texture does not
+// have depth comparisions enabled, the results are also undefined.
+// 
+// In all functions below, the bias parameter is optional for fragment shaders. The bias parameter
+// is not accepted in a vertex shader. For a fragment shader, if bias is present, it is added to
+// the calculated level of detail prior to performing the texture access operation. If the bias
+// parameter is not provided, then the implementation automatically selects level of detail:
+// For a texture that is not mip-mapped, the texture is used directly. If it is mip-mapped and
+// running in a fragment shader, the LOD computed by the implementation is used to do the texture
+// lookup. If it is mip-mapped and running on the vertex shader, then the base texture is used.
+// 
+// The built-ins suffixed with “Lod” are allowed only in a vertex shader. For the “Lod” functions,
+// lod is directly used as the level of detail.
+// 
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 1D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate coord.s is divided by
+// the last component of coord.
+// 
+// XXX
+vec4 texture1DLod (sampler1D sampler, float coord, float lod) {
+    return vec4 (0.0);
+}
+vec4 texture1DProjLod (sampler1D sampler, vec2 coord, float lod) {
+    return texture1DLod (sampler, coord.s / coord.t, lod);
+}
+vec4 texture1DProjLod (sampler1D sampler, vec4 coord, float lod) {
+    return texture1DLod (sampler, coord.s / coord.q, lod);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 2D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate (coord.s, coord.t) is
+// divided by the last component of coord. The third component of coord is ignored for the vec4
+// coord variant.
+// 
+// XXX
+vec4 texture2DLod (sampler2D sampler, vec2 coord, float lod) {
+    return vec4 (0.0);
+}
+vec4 texture2DProjLod (sampler2D sampler, vec3 coord, float lod) {
+    return texture2DLod (sampler, vec2 (coord.s / coord.p, coord.t / coord.p), lod);
+}
+vec4 texture2DProjLod (sampler2D sampler, vec4 coord, float lod) {
+    return texture2DLod (sampler, vec2 (coord.s / coord.q, coord.t / coord.q), lod);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the 3D texture currently bound
+// to sampler. For the projective (“Proj”) versions, the texture coordinate is divided by coord.q.
+// 
+// XXX
+vec4 texture3DLod (sampler3D sampler, vec3 coord, float lod) {
+    return vec4 (0.0);
+}
+vec4 texture3DProjLod (sampler3D sampler, vec4 coord, float lod) {
+    return texture3DLod (sampler, vec3 (coord.s / coord.q, coord.t / coord.q, coord.s / coord.q),
+        lod);
+}
+
+// 
+// Use the texture coordinate coord to do a texture lookup in the cube map texture currently bound
+// to sampler. The direction of coord is used to select which face to do a 2-dimensional texture
+// lookup in, as described in section 3.8.6 in version 1.4 of the OpenGL specification.
+// 
+// XXX
+vec4 textureCubeLod (samplerCube sampler, vec3 coord, float lod) {
+    return vec4 (0.0);
+}
+
+// 
+// Use texture coordinate coord to do a depth comparison lookup on the depth texture bound
+// to sampler, as described in section 3.8.14 of version 1.4 of the OpenGL specification. The 3rd
+// component of coord (coord.p) is used as the R value. The texture bound to sampler must be a
+// depth texture, or results are undefined. For the projective (“Proj”) version of each built-in,
+// the texture coordinate is divide by coord.q, giving a depth value R of coord.p/coord.q. The
+// second component of coord is ignored for the “1D” variants.
+// 
+// XXX
+vec4 shadow1DLod (sampler1DShadow sampler, vec3 coord, float lod) {
+    return vec4 (0.0);
+}
+// XXX
+vec4 shadow2DLod (sampler2DShadow sampler, vec3 coord, float lod) {
+    return vec4 (0.0);
+}
+vec4 shadow1DProjLod(sampler1DShadow sampler, vec4 coord, float lod) {
+    return shadow1DLod (sampler, vec3 (coord.s / coord.q, 0.0, coord.p / coord.q), lod);
+}
+vec4 shadow2DProjLod(sampler2DShadow sampler, vec4 coord, float lod) {
+    return shadow2DLod (sampler, vec3 (coord.s / coord.q, coord.t / coord.q, coord.p / coord.q),
+        lod);
+}
+