2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2006 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 sw_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
69 #define SPAN_VARYING 0x2000
73 /* alternate arrangement for code below */
76 GLubyte sz1
[MAX_WIDTH
][4]; /* primary color */
77 GLushort sz2
[MAX_WIDTH
][4];
78 GLfloat sz4
[MAX_WIDTH
][4];
81 GLubyte sz1
[MAX_WIDTH
][4]; /* specular color and temp storage */
82 GLushort sz2
[MAX_WIDTH
][4];
83 GLfloat sz4
[MAX_WIDTH
][4];
91 * \brief Arrays of fragment values.
93 * These will either be computed from the x/xStep values above or
94 * filled in by glDraw/CopyPixels, etc.
95 * These arrays are separated out of sw_span to conserve memory.
97 typedef struct sw_span_arrays
{
98 GLenum ChanType
; /**< Color channel type, GL_UNSIGNED_BYTE, GL_FLOAT */
101 GLubyte rgba
[MAX_WIDTH
][4]; /**< primary color */
102 GLubyte spec
[MAX_WIDTH
][4]; /**< specular color and temp storage */
105 GLushort rgba
[MAX_WIDTH
][4];
106 GLushort spec
[MAX_WIDTH
][4];
109 GLfloat rgba
[MAX_WIDTH
][4];
110 GLfloat spec
[MAX_WIDTH
][4];
113 /** XXX these are temporary fields, pointing into above color arrays */
117 GLuint index
[MAX_WIDTH
];
118 GLint x
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
119 GLint y
[MAX_WIDTH
]; /**< X/Y used for point/line rendering only */
121 GLfloat fog
[MAX_WIDTH
];
122 GLfloat texcoords
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
][4];
123 GLfloat lambda
[MAX_TEXTURE_COORD_UNITS
][MAX_WIDTH
];
124 GLfloat coverage
[MAX_WIDTH
];
125 GLfloat varying
[MAX_WIDTH
][MAX_VARYING
][4];
127 /** This mask indicates which fragments are alive or culled */
128 GLubyte mask
[MAX_WIDTH
];
134 * \brief Contains data for either a horizontal line or a set of
135 * pixels that are passed through a pipeline of functions before being
138 * The sw_span structure describes the colors, Z, fogcoord, texcoords,
139 * etc for either a horizontal run or an array of independent pixels.
140 * We can either specify a base/step to indicate interpolated values, or
141 * fill in arrays of values. The interpMask and arrayMask bitfields
142 * indicate which are active.
144 * With this structure it's easy to hand-off span rasterization to
145 * subroutines instead of doing it all inline in the triangle functions
146 * like we used to do.
147 * It also cleans up the local variable namespace a great deal.
149 * It would be interesting to experiment with multiprocessor rasterization
150 * with this structure. The triangle rasterizer could simply emit a
151 * stream of these structures which would be consumed by one or more
152 * span-processing threads which could run in parallel.
154 typedef struct sw_span
{
157 /** Only need to process pixels between start <= i < end */
158 /** At this time, start is always zero. */
161 /** This flag indicates that mask[] array is effectively filled with ones */
164 /** either GL_POLYGON, GL_LINE, GL_POLYGON, GL_BITMAP */
167 /** 0 = front-facing span, 1 = back-facing span (for two-sided stencil) */
171 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
172 * which of the x/xStep variables are relevant.
174 GLbitfield interpMask
;
176 /* For horizontal spans, step is the partial derivative wrt X.
177 * For lines, step is the delta from one fragment to the next.
179 #if CHAN_TYPE == GL_FLOAT
180 GLfloat red
, redStep
;
181 GLfloat green
, greenStep
;
182 GLfloat blue
, blueStep
;
183 GLfloat alpha
, alphaStep
;
184 GLfloat specRed
, specRedStep
;
185 GLfloat specGreen
, specGreenStep
;
186 GLfloat specBlue
, specBlueStep
;
187 #else /* CHAN_TYPE == GL_UNSIGNED_BYTE or GL_UNSIGNED_SHORT */
188 GLfixed red
, redStep
;
189 GLfixed green
, greenStep
;
190 GLfixed blue
, blueStep
;
191 GLfixed alpha
, alphaStep
;
192 GLfixed specRed
, specRedStep
;
193 GLfixed specGreen
, specGreenStep
;
194 GLfixed specBlue
, specBlueStep
;
196 GLfixed index
, indexStep
;
197 GLfixed z
, zStep
; /* XXX z should probably be GLuint */
198 GLfloat fog
, fogStep
;
199 GLfloat tex
[MAX_TEXTURE_COORD_UNITS
][4]; /* s, t, r, q */
200 GLfloat texStepX
[MAX_TEXTURE_COORD_UNITS
][4];
201 GLfloat texStepY
[MAX_TEXTURE_COORD_UNITS
][4];
202 GLfixed intTex
[2], intTexStep
[2]; /* s, t only */
203 GLfloat var
[MAX_VARYING
][4];
204 GLfloat varStepX
[MAX_VARYING
][4];
205 GLfloat varStepY
[MAX_VARYING
][4];
207 /* partial derivatives wrt X and Y. */
209 GLfloat w
, dwdx
, dwdy
;
214 GLfloat dsrdx
, dsrdy
;
215 GLfloat dsgdx
, dsgdy
;
216 GLfloat dsbdx
, dsbdy
;
217 GLfloat dfogdx
, dfogdy
;
220 * This bitmask (of \link SpanFlags SPAN_* flags\endlink) indicates
221 * which of the fragment arrays in the span_arrays struct are relevant.
223 GLbitfield arrayMask
;
226 * We store the arrays of fragment values in a separate struct so
227 * that we can allocate sw_span structs on the stack without using
228 * a lot of memory. The span_arrays struct is about 400KB while the
229 * sw_span struct is only about 512 bytes.
236 #define INIT_SPAN(S, PRIMITIVE, END, INTERP_MASK, ARRAY_MASK) \
238 (S).primitive = (PRIMITIVE); \
239 (S).interpMask = (INTERP_MASK); \
240 (S).arrayMask = (ARRAY_MASK); \
244 (S).array = SWRAST_CONTEXT(ctx)->SpanArrays; \
248 typedef void (*texture_sample_func
)(GLcontext
*ctx
,
249 const struct gl_texture_object
*tObj
,
250 GLuint n
, const GLfloat texcoords
[][4],
251 const GLfloat lambda
[], GLchan rgba
[][4]);
253 typedef void (_ASMAPIP blend_func
)( GLcontext
*ctx
, GLuint n
,
254 const GLubyte mask
[],
255 GLvoid
*src
, const GLvoid
*dst
,
258 typedef void (*swrast_point_func
)( GLcontext
*ctx
, const SWvertex
*);
260 typedef void (*swrast_line_func
)( GLcontext
*ctx
,
261 const SWvertex
*, const SWvertex
*);
263 typedef void (*swrast_tri_func
)( GLcontext
*ctx
, const SWvertex
*,
264 const SWvertex
*, const SWvertex
*);
267 typedef void (*validate_texture_image_func
)(GLcontext
*ctx
,
268 struct gl_texture_object
*texObj
,
269 GLuint face
, GLuint level
);
272 /** \defgroup Bitmasks
273 * Bitmasks to indicate which rasterization options are enabled
277 #define ALPHATEST_BIT 0x001 /**< Alpha-test pixels */
278 #define BLEND_BIT 0x002 /**< Blend pixels */
279 #define DEPTH_BIT 0x004 /**< Depth-test pixels */
280 #define FOG_BIT 0x008 /**< Fog pixels */
281 #define LOGIC_OP_BIT 0x010 /**< Apply logic op in software */
282 #define CLIP_BIT 0x020 /**< Scissor or window clip pixels */
283 #define STENCIL_BIT 0x040 /**< Stencil pixels */
284 #define MASKING_BIT 0x080 /**< Do glColorMask or glIndexMask */
285 #define MULTI_DRAW_BIT 0x400 /**< Write to more than one color- */
286 /**< buffer or no buffers. */
287 #define OCCLUSION_BIT 0x800 /**< GL_HP_occlusion_test enabled */
288 #define TEXTURE_BIT 0x1000 /**< Texturing really enabled */
289 #define FRAGPROG_BIT 0x2000 /**< Fragment program enabled */
290 #define ATIFRAGSHADER_BIT 0x4000 /**< ATI Fragment shader enabled */
291 #define CLAMPING_BIT 0x8000 /**< Clamp colors to [0,1] */
294 #define _SWRAST_NEW_RASTERMASK (_NEW_BUFFERS| \
308 * \brief Per-context state that's private to the software rasterizer module.
312 /** Driver interface:
314 struct swrast_device_driver Driver
;
316 /** Configuration mechanisms to make software rasterizer match
317 * characteristics of the hardware rasterizer (if present):
319 GLboolean AllowVertexFog
;
320 GLboolean AllowPixelFog
;
322 /** Derived values, invalidated on statechanges, updated from
323 * _swrast_validate_derived():
325 GLbitfield _RasterMask
;
326 GLfloat _BackfaceSign
;
327 GLboolean _PreferPixelFog
; /* Compute fog blend factor per fragment? */
328 GLboolean _AnyTextureCombine
;
329 GLboolean _FogEnabled
;
330 GLenum _FogMode
; /* either GL_FOG_MODE or fragment program's fog mode */
332 /* Accum buffer temporaries.
334 GLboolean _IntegerAccumMode
; /**< Storing unscaled integers? */
335 GLfloat _IntegerAccumScaler
; /**< Implicit scale factor */
339 GLuint StippleCounter
; /**< Line stipple counter */
342 GLenum Primitive
; /* current primitive being drawn (ala glBegin) */
344 void (*InvalidateState
)( GLcontext
*ctx
, GLbitfield new_state
);
347 * When the NewState mask intersects these masks, we invalidate the
348 * Point/Line/Triangle function pointers below.
351 GLbitfield InvalidatePointMask
;
352 GLbitfield InvalidateLineMask
;
353 GLbitfield InvalidateTriangleMask
;
357 * Device drivers plug in functions for these callbacks.
358 * Will be called when the GL state change mask intersects the above masks.
361 void (*choose_point
)( GLcontext
* );
362 void (*choose_line
)( GLcontext
* );
363 void (*choose_triangle
)( GLcontext
* );
367 * Current point, line and triangle drawing functions.
370 swrast_point_func Point
;
371 swrast_line_func Line
;
372 swrast_tri_func Triangle
;
376 * Placeholders for when separate specular (or secondary color) is
377 * enabled but texturing is not.
380 swrast_point_func SpecPoint
;
381 swrast_line_func SpecLine
;
382 swrast_tri_func SpecTriangle
;
386 * Typically, we'll allocate a sw_span structure as a local variable
387 * and set its 'array' pointer to point to this object. The reason is
388 * this object is big and causes problems when allocated on the stack
391 SWspanarrays
*SpanArrays
;
394 * Used to buffer N GL_POINTS, instead of rendering one by one.
398 /** Internal hooks, kept up to date by the same mechanism as above.
400 blend_func BlendFunc
;
401 texture_sample_func TextureSample
[MAX_TEXTURE_IMAGE_UNITS
];
403 /** Buffer for saving the sampled texture colors.
404 * Needed for GL_ARB_texture_env_crossbar implementation.
408 validate_texture_image_func ValidateTextureImage
;
414 _swrast_validate_derived( GLcontext
*ctx
);
417 #define SWRAST_CONTEXT(ctx) ((SWcontext *)ctx->swrast_context)
419 #define RENDER_START(SWctx, GLctx) \
421 if ((SWctx)->Driver.SpanRenderStart) { \
422 (*(SWctx)->Driver.SpanRenderStart)(GLctx); \
426 #define RENDER_FINISH(SWctx, GLctx) \
428 if ((SWctx)->Driver.SpanRenderFinish) { \
429 (*(SWctx)->Driver.SpanRenderFinish)(GLctx); \
436 * Size of an RGBA pixel, in bytes, for given datatype.
438 #define RGBA_PIXEL_SIZE(TYPE) \
439 ((TYPE == GL_UNSIGNED_BYTE) ? 4 * sizeof(GLubyte) : \
440 ((TYPE == GL_UNSIGNED_SHORT) ? 4 * sizeof(GLushort) \
441 : 4 * sizeof(GLfloat)))
446 * XXX these macros are just bandages for now in order to make
447 * CHAN_BITS==32 compile cleanly.
448 * These should probably go elsewhere at some point.
450 #if CHAN_TYPE == GL_FLOAT
451 #define ChanToFixed(X) (X)
452 #define FixedToChan(X) (X)
454 #define ChanToFixed(X) IntToFixed(X)
455 #define FixedToChan(X) FixedToInt(X)