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      1 /*
      2  * Mesa 3-D graphics library
      3  * Version:  7.5
      4  *
      5  * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.
      6  * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.
      7  *
      8  * Permission is hereby granted, free of charge, to any person obtaining a
      9  * copy of this software and associated documentation files (the "Software"),
     10  * to deal in the Software without restriction, including without limitation
     11  * the rights to use, copy, modify, merge, publish, distribute, sublicense,
     12  * and/or sell copies of the Software, and to permit persons to whom the
     13  * Software is furnished to do so, subject to the following conditions:
     14  *
     15  * The above copyright notice and this permission notice shall be included
     16  * in all copies or substantial portions of the Software.
     17  *
     18  * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
     19  * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
     20  * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
     21  * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
     22  * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
     23  * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
     24  */
     25 
     26 
     27 #ifndef S_SPAN_H
     28 #define S_SPAN_H
     29 
     30 
     31 #include "main/config.h"
     32 #include "main/glheader.h"
     33 #include "main/mtypes.h"
     34 #include "swrast/s_chan.h"
     35 #include "swrast/swrast.h"
     36 
     37 
     38 struct gl_context;
     39 struct gl_renderbuffer;
     40 
     41 
     42 /**
     43  * \defgroup SpanFlags
     44  * Special bitflags to describe span data.
     45  *
     46  * In general, the point/line/triangle functions interpolate/emit the
     47  * attributes specified by swrast->_ActiveAttribs (i.e. FRAT_BIT_* values).
     48  * Some things don't fit into that, though, so we have these flags.
     49  */
     50 /*@{*/
     51 #define SPAN_RGBA       0x01  /**< interpMask and arrayMask */
     52 #define SPAN_Z          0x02  /**< interpMask and arrayMask */
     53 #define SPAN_FLAT       0x04  /**< interpMask: flat shading? */
     54 #define SPAN_XY         0x08  /**< array.x[], y[] valid? */
     55 #define SPAN_MASK       0x10  /**< was array.mask[] filled in by caller? */
     56 #define SPAN_LAMBDA     0x20  /**< array.lambda[] valid? */
     57 #define SPAN_COVERAGE   0x40  /**< array.coverage[] valid? */
     58 /*@}*/
     59 
     60 
     61 /**
     62  * \sw_span_arrays
     63  * \brief Arrays of fragment values.
     64  *
     65  * These will either be computed from the span x/xStep values or
     66  * filled in by glDraw/CopyPixels, etc.
     67  * These arrays are separated out of sw_span to conserve memory.
     68  */
     69 typedef struct sw_span_arrays
     70 {
     71    /** Per-fragment attributes (indexed by FRAG_ATTRIB_* tokens) */
     72    /* XXX someday look at transposing first two indexes for better memory
     73     * access pattern.
     74     */
     75    GLfloat attribs[FRAG_ATTRIB_MAX][SWRAST_MAX_WIDTH][4];
     76 
     77    /** This mask indicates which fragments are alive or culled */
     78    GLubyte mask[SWRAST_MAX_WIDTH];
     79 
     80    GLenum ChanType; /**< Color channel type, GL_UNSIGNED_BYTE, GL_FLOAT */
     81 
     82    /** Attribute arrays that don't fit into attribs[] array above */
     83    /*@{*/
     84    GLubyte rgba8[SWRAST_MAX_WIDTH][4];
     85    GLushort rgba16[SWRAST_MAX_WIDTH][4];
     86    GLchan (*rgba)[4];  /** either == rgba8 or rgba16 */
     87    GLint   x[SWRAST_MAX_WIDTH];  /**< fragment X coords */
     88    GLint   y[SWRAST_MAX_WIDTH];  /**< fragment Y coords */
     89    GLuint  z[SWRAST_MAX_WIDTH];  /**< fragment Z coords */
     90    GLuint  index[SWRAST_MAX_WIDTH];  /**< Color indexes */
     91    GLfloat lambda[MAX_TEXTURE_COORD_UNITS][SWRAST_MAX_WIDTH]; /**< Texture LOD */
     92    GLfloat coverage[SWRAST_MAX_WIDTH];  /**< Fragment coverage for AA/smoothing */
     93    /*@}*/
     94 } SWspanarrays;
     95 
     96 
     97 /**
     98  * The SWspan structure describes the colors, Z, fogcoord, texcoords,
     99  * etc for either a horizontal run or an array of independent pixels.
    100  * We can either specify a base/step to indicate interpolated values, or
    101  * fill in explicit arrays of values.  The interpMask and arrayMask bitfields
    102  * indicate which attributes are active interpolants or arrays, respectively.
    103  *
    104  * It would be interesting to experiment with multiprocessor rasterization
    105  * with this structure.  The triangle rasterizer could simply emit a
    106  * stream of these structures which would be consumed by one or more
    107  * span-processing threads which could run in parallel.
    108  */
    109 typedef struct sw_span
    110 {
    111    /** Coord of first fragment in horizontal span/run */
    112    GLint x, y;
    113 
    114    /** Number of fragments in the span */
    115    GLuint end;
    116 
    117    /** for clipping left edge of spans */
    118    GLuint leftClip;
    119 
    120    /** This flag indicates that mask[] array is effectively filled with ones */
    121    GLboolean writeAll;
    122 
    123    /** either GL_POLYGON, GL_LINE, GL_POLYGON, GL_BITMAP */
    124    GLenum primitive;
    125 
    126    /** 0 = front-facing span, 1 = back-facing span (for two-sided stencil) */
    127    GLuint facing;
    128 
    129    /**
    130     * This bitmask (of  \link SpanFlags SPAN_* flags\endlink) indicates
    131     * which of the attrStart/StepX/StepY variables are relevant.
    132     */
    133    GLbitfield interpMask;
    134 
    135    /** Fragment attribute interpolants */
    136    GLfloat attrStart[FRAG_ATTRIB_MAX][4];   /**< initial value */
    137    GLfloat attrStepX[FRAG_ATTRIB_MAX][4];   /**< dvalue/dx */
    138    GLfloat attrStepY[FRAG_ATTRIB_MAX][4];   /**< dvalue/dy */
    139 
    140    /* XXX the rest of these will go away eventually... */
    141 
    142    /* For horizontal spans, step is the partial derivative wrt X.
    143     * For lines, step is the delta from one fragment to the next.
    144     */
    145    GLfixed red, redStep;
    146    GLfixed green, greenStep;
    147    GLfixed blue, blueStep;
    148    GLfixed alpha, alphaStep;
    149    GLfixed index, indexStep;
    150    GLfixed z, zStep;    /**< XXX z should probably be GLuint */
    151    GLfixed intTex[2], intTexStep[2];  /**< (s,t) for unit[0] only */
    152 
    153    /**
    154     * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
    155     * which of the fragment arrays in the span_arrays struct are relevant.
    156     */
    157    GLbitfield arrayMask;
    158 
    159    /** Mask of FRAG_BIT_x bits */
    160    GLbitfield64 arrayAttribs;
    161 
    162    /**
    163     * We store the arrays of fragment values in a separate struct so
    164     * that we can allocate sw_span structs on the stack without using
    165     * a lot of memory.  The span_arrays struct is about 1.4MB while the
    166     * sw_span struct is only about 512 bytes.
    167     */
    168    SWspanarrays *array;
    169 } SWspan;
    170 
    171 
    172 
    173 #define INIT_SPAN(S, PRIMITIVE)			\
    174 do {						\
    175    (S).primitive = (PRIMITIVE);			\
    176    (S).interpMask = 0x0;			\
    177    (S).arrayMask = 0x0;				\
    178    (S).arrayAttribs = 0x0;			\
    179    (S).end = 0;					\
    180    (S).leftClip = 0;				\
    181    (S).facing = 0;				\
    182    (S).array = SWRAST_CONTEXT(ctx)->SpanArrays;	\
    183 } while (0)
    184 
    185 
    186 
    187 extern void
    188 _swrast_span_default_attribs(struct gl_context *ctx, SWspan *span);
    189 
    190 extern void
    191 _swrast_span_interpolate_z( const struct gl_context *ctx, SWspan *span );
    192 
    193 extern GLfloat
    194 _swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,
    195                        GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,
    196                        GLfloat s, GLfloat t, GLfloat q, GLfloat invQ);
    197 
    198 
    199 extern void
    200 _swrast_write_rgba_span( struct gl_context *ctx, SWspan *span);
    201 
    202 
    203 extern void
    204 _swrast_read_rgba_span(struct gl_context *ctx, struct gl_renderbuffer *rb,
    205                        GLuint n, GLint x, GLint y, GLvoid *rgba);
    206 
    207 extern void
    208 _swrast_put_row(struct gl_context *ctx, struct gl_renderbuffer *rb,
    209                 GLenum datatype,
    210                 GLuint count, GLint x, GLint y,
    211                 const void *values, const GLubyte *mask);
    212 
    213 extern void *
    214 _swrast_get_dest_rgba(struct gl_context *ctx, struct gl_renderbuffer *rb,
    215                       SWspan *span);
    216 
    217 #endif
    218