2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2005 Brian Paul All Rights Reserved.
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27 * \file swrast/s_context.h
28 * \brief Software rasterization context and private types.
29 * \author Keith Whitwell <keith@tungstengraphics.com>
33 * \mainpage swrast module
35 * This module, software rasterization, contains the software fallback
36 * routines for drawing points, lines, triangles, bitmaps and images.
37 * All rendering boils down to writing spans (arrays) of pixels with
38 * particular colors. The span-writing routines must be implemented
39 * by the device driver.
51 * \defgroup SpanFlags SPAN_XXX-flags
52 * Bitmasks to indicate which span_arrays need to be computed
53 * (sw_span::interpMask) or have already been filled
54 * (sw_span::arrayMask)
57 #define SPAN_RGBA 0x001
58 #define SPAN_SPEC 0x002
59 #define SPAN_INDEX 0x004
62 #define SPAN_FOG 0x020
63 #define SPAN_TEXTURE 0x040
64 #define SPAN_INT_TEXTURE 0x080
65 #define SPAN_LAMBDA 0x100
66 #define SPAN_COVERAGE 0x200
67 #define SPAN_FLAT 0x400 /**< flat shading? */
68 /** sw_span::arrayMask only - for span_arrays::x, span_arrays::y */
70 #define SPAN_MASK 0x1000 /**< sw_span::arrayMask only */
76 * \brief Arrays of fragment values.
78 * These will either be computed from the x/xStep values above or
79 * filled in by glDraw/CopyPixels, etc.
80 * These arrays are separated out of sw_span to conserve memory.
83 GLchan rgb
[MAX_WIDTH
][3];
84 GLchan rgba
[MAX_WIDTH
][4];
85 GLuint index
[MAX_WIDTH
];
86 GLchan spec
[MAX_WIDTH
][4]; /* specular color */
87 GLint x
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
88 GLint y
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
90 GLfloat fog
[MAX_WIDTH
];
91 GLfloat texcoords
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
][4];
92 GLfloat lambda
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
];
93 GLfloat coverage
[MAX_WIDTH
];
95 /** This mask indicates if fragment is alive or culled */
96 GLubyte mask
[MAX_WIDTH
];
102 * \brief Contains data for either a horizontal line or a set of
103 * pixels that are passed through a pipeline of functions before being
106 * The sw_span structure describes the colors, Z, fogcoord, texcoords,
107 * etc for either a horizontal run or an array of independent pixels.
108 * We can either specify a base/step to indicate interpolated values, or
109 * fill in arrays of values. The interpMask and arrayMask bitfields
110 * indicate which are active.
112 * With this structure it's easy to hand-off span rasterization to
113 * subroutines instead of doing it all inline in the triangle functions
114 * like we used to do.
115 * It also cleans up the local variable namespace a great deal.
117 * It would be interesting to experiment with multiprocessor rasterization
118 * with this structure. The triangle rasterizer could simply emit a
119 * stream of these structures which would be consumed by one or more
120 * span-processing threads which could run in parallel.
125 /** Only need to process pixels between start <= i < end */
126 /** At this time, start is always zero. */
129 /** This flag indicates that mask[] array is effectively filled with ones */
132 /** either GL_POLYGON, GL_LINE, GL_POLYGON, GL_BITMAP */
135 /** 0 = front-facing span, 1 = back-facing span (for two-sided stencil) */
139 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
140 * which of the x/xStep variables are relevant.
144 /* For horizontal spans, step is the partial derivative wrt X.
145 * For lines, step is the delta from one fragment to the next.
147 #if CHAN_TYPE == GL_FLOAT
148 GLfloat red
, redStep
;
149 GLfloat green
, greenStep
;
150 GLfloat blue
, blueStep
;
151 GLfloat alpha
, alphaStep
;
152 GLfloat specRed
, specRedStep
;
153 GLfloat specGreen
, specGreenStep
;
154 GLfloat specBlue
, specBlueStep
;
155 #else /* CHAN_TYPE == GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT */
156 GLfixed red
, redStep
;
157 GLfixed green
, greenStep
;
158 GLfixed blue
, blueStep
;
159 GLfixed alpha
, alphaStep
;
160 GLfixed specRed
, specRedStep
;
161 GLfixed specGreen
, specGreenStep
;
162 GLfixed specBlue
, specBlueStep
;
164 GLfixed index
, indexStep
;
166 GLfloat fog
, fogStep
;
167 GLfloat tex
[MAX_TEXTURE_COORD_UNITS
][4]; /* s, t, r, q */
168 GLfloat texStepX
[MAX_TEXTURE_COORD_UNITS
][4];
169 GLfloat texStepY
[MAX_TEXTURE_COORD_UNITS
][4];
170 GLfixed intTex
[2], intTexStep
[2]; /* s, t only */
172 /* partial derivatives wrt X and Y. */
174 GLfloat w
, dwdx
, dwdy
;
179 GLfloat dsrdx
, dsrdy
;
180 GLfloat dsgdx
, dsgdy
;
181 GLfloat dsbdx
, dsbdy
;
182 GLfloat dfogdx
, dfogdy
;
185 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
186 * which of the fragment arrays in the span_arrays struct are relevant.
191 * We store the arrays of fragment values in a separate struct so
192 * that we can allocate sw_span structs on the stack without using
193 * a lot of memory. The span_arrays struct is about 400KB while the
194 * sw_span struct is only about 512 bytes.
196 struct span_arrays
*array
;
200 #define INIT_SPAN(S, PRIMITIVE, END, INTERP_MASK, ARRAY_MASK) \
202 (S).primitive = (PRIMITIVE); \
203 (S).interpMask = (INTERP_MASK); \
204 (S).arrayMask = (ARRAY_MASK); \
208 (S).array = SWRAST_CONTEXT(ctx)->SpanArrays; \
212 typedef void (*texture_sample_func
)(GLcontext
*ctx
, GLuint texUnit
,
213 const struct gl_texture_object
*tObj
,
214 GLuint n
, const GLfloat texcoords
[][4],
215 const GLfloat lambda
[], GLchan rgba
[][4]);
217 typedef void (_ASMAPIP blend_func
)( GLcontext
*ctx
, GLuint n
,
218 const GLubyte mask
[],
219 GLchan src
[][4], CONST GLchan dst
[][4] );
221 typedef void (*swrast_point_func
)( GLcontext
*ctx
, const SWvertex
*);
223 typedef void (*swrast_line_func
)( GLcontext
*ctx
,
224 const SWvertex
*, const SWvertex
*);
226 typedef void (*swrast_tri_func
)( GLcontext
*ctx
, const SWvertex
*,
227 const SWvertex
*, const SWvertex
*);
230 /** \defgroup Bitmasks
231 * Bitmasks to indicate which rasterization options are enabled
235 #define ALPHATEST_BIT 0x001 /**< Alpha-test pixels */
236 #define BLEND_BIT 0x002 /**< Blend pixels */
237 #define DEPTH_BIT 0x004 /**< Depth-test pixels */
238 #define FOG_BIT 0x008 /**< Fog pixels */
239 #define LOGIC_OP_BIT 0x010 /**< Apply logic op in software */
240 #define CLIP_BIT 0x020 /**< Scissor or window clip pixels */
241 #define STENCIL_BIT 0x040 /**< Stencil pixels */
242 #define MASKING_BIT 0x080 /**< Do glColorMask or glIndexMask */
243 #define MULTI_DRAW_BIT 0x400 /**< Write to more than one color- */
244 /**< buffer or no buffers. */
245 #define OCCLUSION_BIT 0x800 /**< GL_HP_occlusion_test enabled */
246 #define TEXTURE_BIT 0x1000 /**< Texturing really enabled */
247 #define FRAGPROG_BIT 0x2000 /**< Fragment program enabled */
248 #define ATIFRAGSHADER_BIT 0x4000 /**< ATI Fragment shader enabled */
251 #define _SWRAST_NEW_RASTERMASK (_NEW_BUFFERS| \
269 /** Driver interface:
271 struct swrast_device_driver Driver
;
273 /** Configuration mechanisms to make software rasterizer match
274 * characteristics of the hardware rasterizer (if present):
276 GLboolean AllowVertexFog
;
277 GLboolean AllowPixelFog
;
279 /** Derived values, invalidated on statechanges, updated from
280 * _swrast_validate_derived():
283 GLfloat _MinMagThresh
[MAX_TEXTURE_IMAGE_UNITS
];
284 GLfloat _BackfaceSign
;
285 GLboolean _PreferPixelFog
; /* Compute fog blend factor per fragment? */
286 GLboolean _AnyTextureCombine
;
288 GLboolean _FogEnabled
;
289 GLenum _FogMode
; /* either GL_FOG_MODE or fragment program's fog mode */
291 /* Accum buffer temporaries.
293 GLboolean _IntegerAccumMode
; /**< Storing unscaled integers? */
294 GLfloat _IntegerAccumScaler
; /**< Implicit scale factor */
298 GLuint StippleCounter
; /**< Line stipple counter */
301 GLenum Primitive
; /* current primitive being drawn (ala glBegin) */
302 GLbitfield CurrentBufferBit
; /* exactly one the of DD_*_BIT buffer bits */
304 /** Mechanism to allow driver (like X11) to register further
305 * software rasterization routines.
308 void (*choose_point
)( GLcontext
* );
309 void (*choose_line
)( GLcontext
* );
310 void (*choose_triangle
)( GLcontext
* );
312 GLuint invalidate_point
;
313 GLuint invalidate_line
;
314 GLuint invalidate_triangle
;
317 /** Function pointers for dispatch behind public entrypoints. */
319 void (*InvalidateState
)( GLcontext
*ctx
, GLuint new_state
);
321 swrast_point_func Point
;
322 swrast_line_func Line
;
323 swrast_tri_func Triangle
;
327 * Placeholders for when separate specular (or secondary color) is
328 * enabled but texturing is not.
331 swrast_point_func SpecPoint
;
332 swrast_line_func SpecLine
;
333 swrast_tri_func SpecTriangle
;
337 * Typically, we'll allocate a sw_span structure as a local variable
338 * and set its 'array' pointer to point to this object. The reason is
339 * this object is big and causes problems when allocated on the stack
342 struct span_arrays
*SpanArrays
;
345 * Used to buffer N GL_POINTS, instead of rendering one by one.
347 struct sw_span PointSpan
;
349 /** Internal hooks, kept uptodate by the same mechanism as above.
351 blend_func BlendFunc
;
352 texture_sample_func TextureSample
[MAX_TEXTURE_IMAGE_UNITS
];
354 /** Buffer for saving the sampled texture colors.
355 * Needed for GL_ARB_texture_env_crossbar implementation.
363 _swrast_validate_derived( GLcontext
*ctx
);
366 #define SWRAST_CONTEXT(ctx) ((SWcontext *)ctx->swrast_context)
368 #define RENDER_START(SWctx, GLctx) \
370 if ((SWctx)->Driver.SpanRenderStart) { \
371 (*(SWctx)->Driver.SpanRenderStart)(GLctx); \
375 #define RENDER_FINISH(SWctx, GLctx) \
377 if ((SWctx)->Driver.SpanRenderFinish) { \
378 (*(SWctx)->Driver.SpanRenderFinish)(GLctx); \
385 * XXX these macros are just bandages for now in order to make
386 * CHAN_BITS==32 compile cleanly.
387 * These should probably go elsewhere at some point.
389 #if CHAN_TYPE == GL_FLOAT
390 #define ChanToFixed(X) (X)
391 #define FixedToChan(X) (X)
393 #define ChanToFixed(X) IntToFixed(X)
394 #define FixedToChan(X) FixedToInt(X)
400 _swrast_translate_program( GLcontext
*ctx
);
403 _swrast_execute_codegen_program(GLcontext
*ctx
,
404 const struct fragment_program
*program
,
406 struct fp_machine
*machine
,
407 const struct sw_span
*span
,