src/glsl/link_varyings.h

   1 /*
   2  * Copyright © 2012 Intel Corporation
   3  *
   4  * Permission is hereby granted, free of charge, to any person obtaining a
   5  * copy of this software and associated documentation files (the "Software"),
   6  * to deal in the Software without restriction, including without limitation
   7  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
   8  * and/or sell copies of the Software, and to permit persons to whom the
   9  * Software is furnished to do so, subject to the following conditions:
  10  *
  11  * The above copyright notice and this permission notice (including the next
  12  * paragraph) shall be included in all copies or substantial portions of the
  13  * Software.
  14  *
  15  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
  16  * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
  17  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
  18  * THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
  19  * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING
  20  * FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
  21  * DEALINGS IN THE SOFTWARE.
  22  */
  23
  24 #pragma once
  25 #ifndef GLSL_LINK_VARYINGS_H
  26 #define GLSL_LINK_VARYINGS_H
  27
  28 /**
  29  * \file link_varyings.h
  30  *
  31  * Linker functions related specifically to linking varyings between shader
  32  * stages.
  33  */
  34
  35
  36 #include "main/glheader.h"
  37
  38
  39 struct gl_shader_program;
  40 struct gl_shader;
  41 class ir_variable;
  42
  43
  44 /**
  45  * Data structure describing a varying which is available for use in transform
  46  * feedback.
  47  *
  48  * For example, if the vertex shader contains:
  49  *
  50  *     struct S {
  51  *       vec4 foo;
  52  *       float[3] bar;
  53  *     };
  54  *
  55  *     varying S[2] v;
  56  *
  57  * Then there would be tfeedback_candidate objects corresponding to the
  58  * following varyings:
  59  *
  60  *     v[0].foo
  61  *     v[0].bar
  62  *     v[1].foo
  63  *     v[1].bar
  64  */
  65 struct tfeedback_candidate
  66 {
  67    /**
  68     * Toplevel variable containing this varying.  In the above example, this
  69     * would point to the declaration of the varying v.
  70     */
  71    ir_variable *toplevel_var;
  72
  73    /**
  74     * Type of this varying.  In the above example, this would point to the
  75     * glsl_type for "vec4" or "float[3]".
  76     */
  77    const glsl_type *type;
  78
  79    /**
  80     * Offset within the toplevel variable where this varying occurs (counted
  81     * in multiples of the size of a float).
  82     */
  83    unsigned offset;
  84 };
  85
  86
  87 /**
  88  * Data structure tracking information about a transform feedback declaration
  89  * during linking.
  90  */
  91 class tfeedback_decl
  92 {
  93 public:
  94    void init(struct gl_context *ctx, struct gl_shader_program *prog,
  95              const void *mem_ctx, const char *input);
  96    static bool is_same(const tfeedback_decl &x, const tfeedback_decl &y);
  97    bool assign_location(struct gl_context *ctx,
  98                         struct gl_shader_program *prog);
  99    unsigned get_num_outputs() const;
 100    bool store(struct gl_context *ctx, struct gl_shader_program *prog,
 101               struct gl_transform_feedback_info *info, unsigned buffer,
 102               const unsigned max_outputs) const;
 103    const tfeedback_candidate *find_candidate(gl_shader_program *prog,
 104                                              hash_table *tfeedback_candidates);
 105
 106    bool is_next_buffer_separator() const
 107    {
 108       return this->next_buffer_separator;
 109    }
 110
 111    bool is_varying() const
 112    {
 113       return !this->next_buffer_separator && !this->skip_components;
 114    }
 115
 116    /**
 117     * The total number of varying components taken up by this variable.  Only
 118     * valid if assign_location() has been called.
 119     */
 120    unsigned num_components() const
 121    {
 122       if (this->is_clip_distance_mesa)
 123          return this->size;
 124       else
 125          return this->vector_elements * this->matrix_columns * this->size;
 126    }
 127
 128 private:
 129    /**
 130     * The name that was supplied to glTransformFeedbackVaryings.  Used for
 131     * error reporting and glGetTransformFeedbackVarying().
 132     */
 133    const char *orig_name;
 134
 135    /**
 136     * The name of the variable, parsed from orig_name.
 137     */
 138    const char *var_name;
 139
 140    /**
 141     * True if the declaration in orig_name represents an array.
 142     */
 143    bool is_subscripted;
 144
 145    /**
 146     * If is_subscripted is true, the subscript that was specified in orig_name.
 147     */
 148    unsigned array_subscript;
 149
 150    /**
 151     * True if the variable is gl_ClipDistance and the driver lowers
 152     * gl_ClipDistance to gl_ClipDistanceMESA.
 153     */
 154    bool is_clip_distance_mesa;
 155
 156    /**
 157     * The vertex shader output location that the linker assigned for this
 158     * variable.  -1 if a location hasn't been assigned yet.
 159     */
 160    int location;
 161
 162    /**
 163     * If non-zero, then this variable may be packed along with other variables
 164     * into a single varying slot, so this offset should be applied when
 165     * accessing components.  For example, an offset of 1 means that the x
 166     * component of this variable is actually stored in component y of the
 167     * location specified by \c location.
 168     *
 169     * Only valid if location != -1.
 170     */
 171    unsigned location_frac;
 172
 173    /**
 174     * If location != -1, the number of vector elements in this variable, or 1
 175     * if this variable is a scalar.
 176     */
 177    unsigned vector_elements;
 178
 179    /**
 180     * If location != -1, the number of matrix columns in this variable, or 1
 181     * if this variable is not a matrix.
 182     */
 183    unsigned matrix_columns;
 184
 185    /** Type of the varying returned by glGetTransformFeedbackVarying() */
 186    GLenum type;
 187
 188    /**
 189     * If location != -1, the size that should be returned by
 190     * glGetTransformFeedbackVarying().
 191     */
 192    unsigned size;
 193
 194    /**
 195     * How many components to skip. If non-zero, this is
 196     * gl_SkipComponents{1,2,3,4} from ARB_transform_feedback3.
 197     */
 198    unsigned skip_components;
 199
 200    /**
 201     * Whether this is gl_NextBuffer from ARB_transform_feedback3.
 202     */
 203    bool next_buffer_separator;
 204
 205    /**
 206     * If find_candidate() has been called, pointer to the tfeedback_candidate
 207     * data structure that was found.  Otherwise NULL.
 208     */
 209    const tfeedback_candidate *matched_candidate;
 210 };
 211
 212
 213 bool
 214 cross_validate_outputs_to_inputs(struct gl_shader_program *prog,
 215                                  gl_shader *producer, gl_shader *consumer);
 216
 217 bool
 218 parse_tfeedback_decls(struct gl_context *ctx, struct gl_shader_program *prog,
 219                       const void *mem_ctx, unsigned num_names,
 220                       char **varying_names, tfeedback_decl *decls);
 221
 222 bool
 223 store_tfeedback_info(struct gl_context *ctx, struct gl_shader_program *prog,
 224                      unsigned num_tfeedback_decls,
 225                      tfeedback_decl *tfeedback_decls);
 226
 227 bool
 228 assign_varying_locations(struct gl_context *ctx,
 229                          void *mem_ctx,
 230                          struct gl_shader_program *prog,
 231                          gl_shader *producer, gl_shader *consumer,
 232                          unsigned num_tfeedback_decls,
 233                          tfeedback_decl *tfeedback_decls);
 234
 235 #endif /* GLSL_LINK_VARYINGS_H */