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/*

 * Mesa 3-D graphics library

 * Version:  7.5

 *

 * Copyright (C) 1999-2008  Brian Paul   All Rights Reserved.

 * Copyright (C) 2009  VMware, Inc.  All Rights Reserved.

 *

 * Permission is hereby granted, free of charge, to any person obtaining a

 * copy of this software and associated documentation files (the "Software"),

 * to deal in the Software without restriction, including without limitation

 * the rights to use, copy, modify, merge, publish, distribute, sublicense,

 * and/or sell copies of the Software, and to permit persons to whom the

 * Software is furnished to do so, subject to the following conditions:

 *

 * The above copyright notice and this permission notice shall be included

 * in all copies or substantial portions of the Software.

 *

 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS

 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,

 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL

 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN

 * AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN

 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

 */

#ifndef S_SPAN_H

#define S_SPAN_H

#include "swrast.h"

/**

 * \defgroup SpanFlags

 * Special bitflags to describe span data.

 *

 * In general, the point/line/triangle functions interpolate/emit the

 * attributes specified by swrast->_ActiveAttribs (i.e. FRAT_BIT_* values).

 * Some things don't fit into that, though, so we have these flags.

 */

/*@{*/

#define SPAN_RGBA       0x01  /**< interpMask and arrayMask */

#define SPAN_Z          0x02  /**< interpMask and arrayMask */

#define SPAN_FLAT       0x04  /**< interpMask: flat shading? */

#define SPAN_XY         0x08  /**< array.x[], y[] valid? */

#define SPAN_MASK       0x10  /**< was array.mask[] filled in by caller? */

#define SPAN_LAMBDA     0x20  /**< array.lambda[] valid? */

#define SPAN_COVERAGE   0x40  /**< array.coverage[] valid? */

/*@}*/

/**

 * \sw_span_arrays

 * \brief Arrays of fragment values.

 *

 * These will either be computed from the span x/xStep values or

 * filled in by glDraw/CopyPixels, etc.

 * These arrays are separated out of sw_span to conserve memory.

 */

typedef struct sw_span_arrays

{

   /** Per-fragment attributes (indexed by FRAG_ATTRIB_* tokens) */

   /* XXX someday look at transposing first two indexes for better memory

    * access pattern.

    */

   GLfloat attribs[FRAG_ATTRIB_MAX][MAX_WIDTH][4];

   /** This mask indicates which fragments are alive or culled */

   GLubyte mask[MAX_WIDTH];

   GLenum ChanType; /**< Color channel type, GL_UNSIGNED_BYTE, GL_FLOAT */

   /** Attribute arrays that don't fit into attribs[] array above */

   /*@{*/

   GLubyte rgba8[MAX_WIDTH][4];

   GLushort rgba16[MAX_WIDTH][4];

   GLchan (*rgba)[4];  /** either == rgba8 or rgba16 */

   GLint   x[MAX_WIDTH];  /**< fragment X coords */

   GLint   y[MAX_WIDTH];  /**< fragment Y coords */

   GLuint  z[MAX_WIDTH];  /**< fragment Z coords */

   GLuint  index[MAX_WIDTH];  /**< Color indexes */

   GLfloat lambda[MAX_TEXTURE_COORD_UNITS][MAX_WIDTH]; /**< Texture LOD */

   GLfloat coverage[MAX_WIDTH];  /**< Fragment coverage for AA/smoothing */

   /*@}*/

} SWspanarrays;

/**

 * The SWspan structure describes the colors, Z, fogcoord, texcoords,

 * etc for either a horizontal run or an array of independent pixels.

 * We can either specify a base/step to indicate interpolated values, or

 * fill in explicit arrays of values.  The interpMask and arrayMask bitfields

 * indicate which attributes are active interpolants or arrays, respectively.

 *

 * It would be interesting to experiment with multiprocessor rasterization

 * with this structure.  The triangle rasterizer could simply emit a

 * stream of these structures which would be consumed by one or more

 * span-processing threads which could run in parallel.

 */

typedef struct sw_span

{

   /** Coord of first fragment in horizontal span/run */

   GLint x, y;

   /** Number of fragments in the span */

   GLuint end;

   /** for clipping left edge of spans */

   GLuint leftClip;

   /** This flag indicates that mask[] array is effectively filled with ones */

   GLboolean writeAll;

   /** either GL_POLYGON, GL_LINE, GL_POLYGON, GL_BITMAP */

   GLenum primitive;

   /** 0 = front-facing span, 1 = back-facing span (for two-sided stencil) */

   GLuint facing;

   /**

    * This bitmask (of  \link SpanFlags SPAN_* flags\endlink) indicates

    * which of the attrStart/StepX/StepY variables are relevant.

    */

   GLbitfield interpMask;

   /** Fragment attribute interpolants */

   GLfloat attrStart[FRAG_ATTRIB_MAX][4];   /**< initial value */

   GLfloat attrStepX[FRAG_ATTRIB_MAX][4];   /**< dvalue/dx */

   GLfloat attrStepY[FRAG_ATTRIB_MAX][4];   /**< dvalue/dy */

   /* XXX the rest of these will go away eventually... */

   /* For horizontal spans, step is the partial derivative wrt X.

    * For lines, step is the delta from one fragment to the next.

    */

   GLfixed red, redStep;

   GLfixed green, greenStep;

   GLfixed blue, blueStep;

   GLfixed alpha, alphaStep;

   GLfixed index, indexStep;

   GLfixed z, zStep;    /**< XXX z should probably be GLuint */

   GLfixed intTex[2], intTexStep[2];  /**< (s,t) for unit[0] only */

   /**

    * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates

    * which of the fragment arrays in the span_arrays struct are relevant.

    */

   GLbitfield arrayMask;

   GLbitfield arrayAttribs;

   /**

    * We store the arrays of fragment values in a separate struct so

    * that we can allocate sw_span structs on the stack without using

    * a lot of memory.  The span_arrays struct is about 1.4MB while the

    * sw_span struct is only about 512 bytes.

    */

   SWspanarrays *array;

} SWspan;

#define INIT_SPAN(S, PRIMITIVE)			\

do {						\

   (S).primitive = (PRIMITIVE);			\

   (S).interpMask = 0x0;			\

   (S).arrayMask = 0x0;				\

   (S).arrayAttribs = 0x0;			\

   (S).end = 0;					\

   (S).leftClip = 0;				\

   (S).facing = 0;				\

   (S).array = SWRAST_CONTEXT(ctx)->SpanArrays;	\

} while (0)

extern void

_swrast_span_default_attribs(struct gl_context *ctx, SWspan *span);

extern void

_swrast_span_interpolate_z( const struct gl_context *ctx, SWspan *span );

extern GLfloat

_swrast_compute_lambda(GLfloat dsdx, GLfloat dsdy, GLfloat dtdx, GLfloat dtdy,

                       GLfloat dqdx, GLfloat dqdy, GLfloat texW, GLfloat texH,

                       GLfloat s, GLfloat t, GLfloat q, GLfloat invQ);

extern void

_swrast_write_rgba_span( struct gl_context *ctx, SWspan *span);

extern void

_swrast_read_rgba_span(struct gl_context *ctx, struct gl_renderbuffer *rb,

                       GLuint n, GLint x, GLint y, GLenum type, GLvoid *rgba);

extern void

_swrast_get_values(struct gl_context *ctx, struct gl_renderbuffer *rb,

                   GLuint count, const GLint x[], const GLint y[],

                   void *values, GLuint valueSize);

extern void

_swrast_put_row(struct gl_context *ctx, struct gl_renderbuffer *rb,

                GLuint count, GLint x, GLint y,

                const GLvoid *values, GLuint valueSize);

extern void

_swrast_get_row(struct gl_context *ctx, struct gl_renderbuffer *rb,

                GLuint count, GLint x, GLint y,

                GLvoid *values, GLuint valueSize);

extern void *

_swrast_get_dest_rgba(struct gl_context *ctx, struct gl_renderbuffer *rb,

                      SWspan *span);

#endif