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 in (sw_span::arrayMask)
56 #define SPAN_RGBA 0x001
57 #define SPAN_SPEC 0x002
58 #define SPAN_INDEX 0x004
61 #define SPAN_FOG 0x020
62 #define SPAN_TEXTURE 0x040
63 #define SPAN_INT_TEXTURE 0x080
64 #define SPAN_LAMBDA 0x100
65 #define SPAN_COVERAGE 0x200
66 #define SPAN_FLAT 0x400 /**< flat shading? */
68 #define SPAN_MASK 0x1000
74 * \brief Arrays of fragment values.
76 * These will either be computed from the x/xStep values above or
77 * filled in by glDraw/CopyPixels, etc.
78 * These arrays are separated out of sw_span to conserve memory.
81 /* XXX the next three fields could go into a union */
82 GLchan rgb
[MAX_WIDTH
][3];
83 GLchan rgba
[MAX_WIDTH
][4];
84 GLuint index
[MAX_WIDTH
];
85 GLchan spec
[MAX_WIDTH
][4]; /* specular color */
86 GLint x
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
87 GLint y
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
89 GLfloat fog
[MAX_WIDTH
];
90 GLfloat texcoords
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
][4];
91 GLfloat lambda
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
];
92 GLfloat coverage
[MAX_WIDTH
];
94 /** This mask indicates which fragments are alive or culled */
95 GLubyte mask
[MAX_WIDTH
];
101 * \brief Contains data for either a horizontal line or a set of
102 * pixels that are passed through a pipeline of functions before being
105 * The sw_span structure describes the colors, Z, fogcoord, texcoords,
106 * etc for either a horizontal run or an array of independent pixels.
107 * We can either specify a base/step to indicate interpolated values, or
108 * fill in arrays of values. The interpMask and arrayMask bitfields
109 * indicate which are active.
111 * With this structure it's easy to hand-off span rasterization to
112 * subroutines instead of doing it all inline in the triangle functions
113 * like we used to do.
114 * It also cleans up the local variable namespace a great deal.
116 * It would be interesting to experiment with multiprocessor rasterization
117 * with this structure. The triangle rasterizer could simply emit a
118 * stream of these structures which would be consumed by one or more
119 * span-processing threads which could run in parallel.
124 /** Only need to process pixels between start <= i < end */
125 /** At this time, start is always zero. */
128 /** This flag indicates that mask[] array is effectively filled with ones */
131 /** either GL_POLYGON, GL_LINE, GL_POLYGON, GL_BITMAP */
134 /** 0 = front-facing span, 1 = back-facing span (for two-sided stencil) */
138 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
139 * which of the x/xStep variables are relevant.
141 GLbitfield interpMask
;
143 /* For horizontal spans, step is the partial derivative wrt X.
144 * For lines, step is the delta from one fragment to the next.
146 #if CHAN_TYPE == GL_FLOAT
147 GLfloat red
, redStep
;
148 GLfloat green
, greenStep
;
149 GLfloat blue
, blueStep
;
150 GLfloat alpha
, alphaStep
;
151 GLfloat specRed
, specRedStep
;
152 GLfloat specGreen
, specGreenStep
;
153 GLfloat specBlue
, specBlueStep
;
154 #else /* CHAN_TYPE == GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT */
155 GLfixed red
, redStep
;
156 GLfixed green
, greenStep
;
157 GLfixed blue
, blueStep
;
158 GLfixed alpha
, alphaStep
;
159 GLfixed specRed
, specRedStep
;
160 GLfixed specGreen
, specGreenStep
;
161 GLfixed specBlue
, specBlueStep
;
163 GLfixed index
, indexStep
;
164 GLfixed z
, zStep
; /* XXX z should probably be GLuint */
165 GLfloat fog
, fogStep
;
166 GLfloat tex
[MAX_TEXTURE_COORD_UNITS
][4]; /* s, t, r, q */
167 GLfloat texStepX
[MAX_TEXTURE_COORD_UNITS
][4];
168 GLfloat texStepY
[MAX_TEXTURE_COORD_UNITS
][4];
169 GLfixed intTex
[2], intTexStep
[2]; /* s, t only */
171 /* partial derivatives wrt X and Y. */
173 GLfloat w
, dwdx
, dwdy
;
178 GLfloat dsrdx
, dsrdy
;
179 GLfloat dsgdx
, dsgdy
;
180 GLfloat dsbdx
, dsbdy
;
181 GLfloat dfogdx
, dfogdy
;
184 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
185 * which of the fragment arrays in the span_arrays struct are relevant.
187 GLbitfield arrayMask
;
190 * We store the arrays of fragment values in a separate struct so
191 * that we can allocate sw_span structs on the stack without using
192 * a lot of memory. The span_arrays struct is about 400KB while the
193 * sw_span struct is only about 512 bytes.
195 struct span_arrays
*array
;
199 #define INIT_SPAN(S, PRIMITIVE, END, INTERP_MASK, ARRAY_MASK) \
201 (S).primitive = (PRIMITIVE); \
202 (S).interpMask = (INTERP_MASK); \
203 (S).arrayMask = (ARRAY_MASK); \
207 (S).array = SWRAST_CONTEXT(ctx)->SpanArrays; \
211 typedef void (*texture_sample_func
)(GLcontext
*ctx
,
212 const struct gl_texture_object
*tObj
,
213 GLuint n
, const GLfloat texcoords
[][4],
214 const GLfloat lambda
[], GLchan rgba
[][4]);
216 typedef void (_ASMAPIP blend_func
)( GLcontext
*ctx
, GLuint n
,
217 const GLubyte mask
[],
218 GLchan src
[][4], CONST GLchan dst
[][4] );
220 typedef void (*swrast_point_func
)( GLcontext
*ctx
, const SWvertex
*);
222 typedef void (*swrast_line_func
)( GLcontext
*ctx
,
223 const SWvertex
*, const SWvertex
*);
225 typedef void (*swrast_tri_func
)( GLcontext
*ctx
, const SWvertex
*,
226 const SWvertex
*, const SWvertex
*);
229 /** \defgroup Bitmasks
230 * Bitmasks to indicate which rasterization options are enabled
234 #define ALPHATEST_BIT 0x001 /**< Alpha-test pixels */
235 #define BLEND_BIT 0x002 /**< Blend pixels */
236 #define DEPTH_BIT 0x004 /**< Depth-test pixels */
237 #define FOG_BIT 0x008 /**< Fog pixels */
238 #define LOGIC_OP_BIT 0x010 /**< Apply logic op in software */
239 #define CLIP_BIT 0x020 /**< Scissor or window clip pixels */
240 #define STENCIL_BIT 0x040 /**< Stencil pixels */
241 #define MASKING_BIT 0x080 /**< Do glColorMask or glIndexMask */
242 #define MULTI_DRAW_BIT 0x400 /**< Write to more than one color- */
243 /**< buffer or no buffers. */
244 #define OCCLUSION_BIT 0x800 /**< GL_HP_occlusion_test enabled */
245 #define TEXTURE_BIT 0x1000 /**< Texturing really enabled */
246 #define FRAGPROG_BIT 0x2000 /**< Fragment program enabled */
247 #define ATIFRAGSHADER_BIT 0x4000 /**< ATI Fragment shader enabled */
248 #define CLAMPING_BIT 0x8000 /**< Clamp colors to [0,1] */
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():
282 GLbitfield _RasterMask
;
283 GLfloat _BackfaceSign
;
284 GLboolean _PreferPixelFog
; /* Compute fog blend factor per fragment? */
285 GLboolean _AnyTextureCombine
;
287 GLboolean _FogEnabled
;
288 GLenum _FogMode
; /* either GL_FOG_MODE or fragment program's fog mode */
290 /* Accum buffer temporaries.
292 GLboolean _IntegerAccumMode
; /**< Storing unscaled integers? */
293 GLfloat _IntegerAccumScaler
; /**< Implicit scale factor */
297 GLuint StippleCounter
; /**< Line stipple counter */
300 GLenum Primitive
; /* current primitive being drawn (ala glBegin) */
302 /** Mechanism to allow driver (like X11) to register further
303 * software rasterization routines.
306 void (*choose_point
)( GLcontext
* );
307 void (*choose_line
)( GLcontext
* );
308 void (*choose_triangle
)( GLcontext
* );
310 GLbitfield invalidate_point
;
311 GLbitfield invalidate_line
;
312 GLbitfield invalidate_triangle
;
315 /** Function pointers for dispatch behind public entrypoints. */
317 void (*InvalidateState
)( GLcontext
*ctx
, GLbitfield new_state
);
319 swrast_point_func Point
;
320 swrast_line_func Line
;
321 swrast_tri_func Triangle
;
325 * Placeholders for when separate specular (or secondary color) is
326 * enabled but texturing is not.
329 swrast_point_func SpecPoint
;
330 swrast_line_func SpecLine
;
331 swrast_tri_func SpecTriangle
;
335 * Typically, we'll allocate a sw_span structure as a local variable
336 * and set its 'array' pointer to point to this object. The reason is
337 * this object is big and causes problems when allocated on the stack
340 struct span_arrays
*SpanArrays
;
343 * Used to buffer N GL_POINTS, instead of rendering one by one.
345 struct sw_span PointSpan
;
347 /** Internal hooks, kept up to date by the same mechanism as above.
349 blend_func BlendFunc
;
350 texture_sample_func TextureSample
[MAX_TEXTURE_IMAGE_UNITS
];
352 /** Buffer for saving the sampled texture colors.
353 * Needed for GL_ARB_texture_env_crossbar implementation.
361 _swrast_validate_derived( GLcontext
*ctx
);
364 #define SWRAST_CONTEXT(ctx) ((SWcontext *)ctx->swrast_context)
366 #define RENDER_START(SWctx, GLctx) \
368 if ((SWctx)->Driver.SpanRenderStart) { \
369 (*(SWctx)->Driver.SpanRenderStart)(GLctx); \
373 #define RENDER_FINISH(SWctx, GLctx) \
375 if ((SWctx)->Driver.SpanRenderFinish) { \
376 (*(SWctx)->Driver.SpanRenderFinish)(GLctx); \
383 * XXX these macros are just bandages for now in order to make
384 * CHAN_BITS==32 compile cleanly.
385 * These should probably go elsewhere at some point.
387 #if CHAN_TYPE == GL_FLOAT
388 #define ChanToFixed(X) (X)
389 #define FixedToChan(X) (X)
391 #define ChanToFixed(X) IntToFixed(X)
392 #define FixedToChan(X) FixedToInt(X)