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Diffstat (limited to 'nx-X11/extras/Mesa/src/mesa/shader/slang/library/slang_fragment_builtin.gc')
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diff --git a/nx-X11/extras/Mesa/src/mesa/shader/slang/library/slang_fragment_builtin.gc b/nx-X11/extras/Mesa/src/mesa/shader/slang/library/slang_fragment_builtin.gc new file mode 100755 index 000000000..b4c5aa3ec --- /dev/null +++ b/nx-X11/extras/Mesa/src/mesa/shader/slang/library/slang_fragment_builtin.gc @@ -0,0 +1,366 @@ + +// +// TODO: +// - implement texture1D, texture2D, texture3D, textureCube, +// - implement shadow1D, shadow2D, +// - implement dFdx, dFdy, +// + +// +// From Shader Spec, ver. 1.10, rev. 59 +// +// The output of the fragment shader is processed by the fixed function operations at the back end +// of the OpenGL pipeline. Fragment shaders output values to the OpenGL pipeline using the built-in +// variables gl_FragColor, gl_FragData and gl_FragDepth, unless the discard keyword is executed. +// +// 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 executions of the +// shader that take that path. That is, if a shader statically contains a write gl_FragDepth, then +// it is responsible for always writing it. +// +// (A shader contains a static assignment to a variable x if, after pre-processing, the shader +// contains statement that would write x, whether or not run-time flow of control will cause +// that statement to be executed.) +// +// The variable gl_FragData is an array. Writing to gl_FragData[n] specifies the fragment data +// that will be used by the subsequent fixed functionality pipeline for data n. If subsequent +// fixed functionality consumes fragment data and an execution of a fragment shader does not +// write a value to it, then the fragment data consumed is undefined. +// +// If a shader statically assigns a value to gl_FragColor, it may not assign a value to any element +// of gl_FragData. If a shader statically writes a value to any element of gl_FragData, it may not +// assign a value to gl_FragColor. That is, a shader may assign values to either gl_FragColor or +// gl_FragData, but not both. +// +// If a shader executes the discard keyword, the fragment is discarded, and the values of +// gl_FragDepth, gl_FragColor and gl_FragData 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: +// + +__fixed_input vec4 gl_FragCoord; +__fixed_input bool gl_FrontFacing; +__fixed_output vec4 gl_FragColor; +__fixed_output vec4 gl_FragData[gl_MaxDrawBuffers]; +__fixed_output 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_MaxTextureCoords +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. +// + +// +// 8.7 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 that represents a depth texture with depth +// comparisons turned on, then results are undefined. If a shadow texture call is made to a sampler +// that represents a depth texture with depth comparisions turned off, the results are undefined. +// If a shadow texture call is made to a sampler that does not represent a depth texture, then +// results are 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); +} + +// +// 8.8 Fragment Processing Functions +// +// 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)); +} + |