2 * Mesa 3-D graphics library
5 * Copyright (C) 1999-2007 Brian Paul All Rights Reserved.
7 * Permission is hereby granted, free of charge, to any person obtaining a
8 * copy of this software and associated documentation files (the "Software"),
9 * to deal in the Software without restriction, including without limitation
10 * the rights to use, copy, modify, merge, publish, distribute, sublicense,
11 * and/or sell copies of the Software, and to permit persons to whom the
12 * Software is furnished to do so, subject to the following conditions:
14 * The above copyright notice and this permission notice shall be included
15 * in all copies or substantial portions of the Software.
17 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
18 * OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
19 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL
20 * BRIAN PAUL BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN
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22 * CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
27 * Line Rasterizer Template
29 * This file is #include'd to generate custom line rasterizers.
31 * The following macros may be defined to indicate what auxillary information
32 * must be interplated along the line:
33 * INTERP_Z - if defined, interpolate Z values
34 * INTERP_ATTRIBS - if defined, interpolate attribs (texcoords, varying, etc)
36 * When one can directly address pixels in the color buffer the following
37 * macros can be defined and used to directly compute pixel addresses during
38 * rasterization (see pixelPtr):
39 * PIXEL_TYPE - the datatype of a pixel (GLubyte, GLushort, GLuint)
40 * BYTES_PER_ROW - number of bytes per row in the color buffer
41 * PIXEL_ADDRESS(X,Y) - returns the address of pixel at (X,Y) where
42 * Y==0 at bottom of screen and increases upward.
44 * Similarly, for direct depth buffer access, this type is used for depth
46 * DEPTH_TYPE - either GLushort or GLuint
48 * Optionally, one may provide one-time setup code
49 * SETUP_CODE - code which is to be executed once per line
51 * To actually "plot" each pixel the PLOT macro must be defined...
52 * PLOT(X,Y) - code to plot a pixel. Example:
55 * color = pack_rgb( FixedToInt(r0), FixedToInt(g0),
57 * put_pixel( X, Y, color );
60 * This code was designed for the origin to be in the lower-left corner.
66 NAME( struct gl_context *ctx, const SWvertex *vert0, const SWvertex *vert1 )
68 const SWcontext *swrast = SWRAST_CONTEXT(ctx);
70 GLuint interpFlags = 0;
71 GLint x0 = (GLint) vert0->attrib[FRAG_ATTRIB_WPOS][0];
72 GLint x1 = (GLint) vert1->attrib[FRAG_ATTRIB_WPOS][0];
73 GLint y0 = (GLint) vert0->attrib[FRAG_ATTRIB_WPOS][1];
74 GLint y1 = (GLint) vert1->attrib[FRAG_ATTRIB_WPOS][1];
78 #if defined(DEPTH_TYPE)
79 const GLint depthBits = ctx->DrawBuffer->Visual.depthBits;
80 const GLint fixedToDepthShift = depthBits <= 16 ? FIXED_SHIFT : 0;
81 struct gl_renderbuffer *zrb = ctx->DrawBuffer->Attachment[BUFFER_DEPTH].Renderbuffer;
82 #define FixedToDepth(F) ((F) >> fixedToDepthShift)
83 GLint zPtrXstep, zPtrYstep;
85 #elif defined(INTERP_Z)
86 const GLint depthBits = ctx->DrawBuffer->Visual.depthBits;
90 GLint pixelXstep, pixelYstep;
99 /* Cull primitives with malformed coordinates.
102 GLfloat tmp = vert0->attrib[FRAG_ATTRIB_WPOS][0] + vert0->attrib[FRAG_ATTRIB_WPOS][1]
103 + vert1->attrib[FRAG_ATTRIB_WPOS][0] + vert1->attrib[FRAG_ATTRIB_WPOS][1];
104 if (IS_INF_OR_NAN(tmp))
109 printf("%s():\n", __FUNCTION__);
110 printf(" (%f, %f, %f) -> (%f, %f, %f)\n",
111 vert0->attrib[FRAG_ATTRIB_WPOS][0],
112 vert0->attrib[FRAG_ATTRIB_WPOS][1],
113 vert0->attrib[FRAG_ATTRIB_WPOS][2],
114 vert1->attrib[FRAG_ATTRIB_WPOS][0],
115 vert1->attrib[FRAG_ATTRIB_WPOS][1],
116 vert1->attrib[FRAG_ATTRIB_WPOS][2]);
117 printf(" (%d, %d, %d) -> (%d, %d, %d)\n",
118 vert0->color[0], vert0->color[1], vert0->color[2],
119 vert1->color[0], vert1->color[1], vert1->color[2]);
120 printf(" (%d, %d, %d) -> (%d, %d, %d)\n",
121 vert0->specular[0], vert0->specular[1], vert0->specular[2],
122 vert1->specular[0], vert1->specular[1], vert1->specular[2]);
126 * Despite being clipped to the view volume, the line's window coordinates
127 * may just lie outside the window bounds. That is, if the legal window
128 * coordinates are [0,W-1][0,H-1], it's possible for x==W and/or y==H.
129 * This quick and dirty code nudges the endpoints inside the window if
134 GLint w = ctx->DrawBuffer->Width;
135 GLint h = ctx->DrawBuffer->Height;
136 if ((x0==w) | (x1==w)) {
137 if ((x0==w) & (x1==w))
142 if ((y0==h) | (y1==h)) {
143 if ((y0==h) & (y1==h))
153 if (dx == 0 && dy == 0)
157 printf("%s %d,%d %g %g %g %g %g %g %g %g\n", __FUNCTION__, dx, dy,
158 vert0->attrib[FRAG_ATTRIB_COL1][0],
159 vert0->attrib[FRAG_ATTRIB_COL1][1],
160 vert0->attrib[FRAG_ATTRIB_COL1][2],
161 vert0->attrib[FRAG_ATTRIB_COL1][3],
162 vert1->attrib[FRAG_ATTRIB_COL1][0],
163 vert1->attrib[FRAG_ATTRIB_COL1][1],
164 vert1->attrib[FRAG_ATTRIB_COL1][2],
165 vert1->attrib[FRAG_ATTRIB_COL1][3]);
169 zPtr = (DEPTH_TYPE *) zrb->GetPointer(ctx, zrb, x0, y0);
172 pixelPtr = (PIXEL_TYPE *) PIXEL_ADDRESS(x0,y0);
176 dx = -dx; /* make positive */
179 zPtrXstep = -((GLint)sizeof(DEPTH_TYPE));
182 pixelXstep = -((GLint)sizeof(PIXEL_TYPE));
188 zPtrXstep = ((GLint)sizeof(DEPTH_TYPE));
191 pixelXstep = ((GLint)sizeof(PIXEL_TYPE));
196 dy = -dy; /* make positive */
199 zPtrYstep = -((GLint) (ctx->DrawBuffer->Width * sizeof(DEPTH_TYPE)));
202 pixelYstep = BYTES_PER_ROW;
208 zPtrYstep = (GLint) (ctx->DrawBuffer->Width * sizeof(DEPTH_TYPE));
211 pixelYstep = -(BYTES_PER_ROW);
218 numPixels = MAX2(dx, dy);
221 * Span setup: compute start and step values for all interpolated values.
223 interpFlags |= SPAN_RGBA;
224 if (ctx->Light.ShadeModel == GL_SMOOTH) {
225 span.red = ChanToFixed(vert0->color[0]);
226 span.green = ChanToFixed(vert0->color[1]);
227 span.blue = ChanToFixed(vert0->color[2]);
228 span.alpha = ChanToFixed(vert0->color[3]);
229 span.redStep = (ChanToFixed(vert1->color[0]) - span.red ) / numPixels;
230 span.greenStep = (ChanToFixed(vert1->color[1]) - span.green) / numPixels;
231 span.blueStep = (ChanToFixed(vert1->color[2]) - span.blue ) / numPixels;
232 span.alphaStep = (ChanToFixed(vert1->color[3]) - span.alpha) / numPixels;
235 span.red = ChanToFixed(vert1->color[0]);
236 span.green = ChanToFixed(vert1->color[1]);
237 span.blue = ChanToFixed(vert1->color[2]);
238 span.alpha = ChanToFixed(vert1->color[3]);
244 #if defined(INTERP_Z) || defined(DEPTH_TYPE)
245 interpFlags |= SPAN_Z;
247 if (depthBits <= 16) {
248 span.z = FloatToFixed(vert0->attrib[FRAG_ATTRIB_WPOS][2]) + FIXED_HALF;
249 span.zStep = FloatToFixed( vert1->attrib[FRAG_ATTRIB_WPOS][2]
250 - vert0->attrib[FRAG_ATTRIB_WPOS][2]) / numPixels;
253 /* don't use fixed point */
254 span.z = (GLuint) vert0->attrib[FRAG_ATTRIB_WPOS][2];
255 span.zStep = (GLint) (( vert1->attrib[FRAG_ATTRIB_WPOS][2]
256 - vert0->attrib[FRAG_ATTRIB_WPOS][2]) / numPixels);
260 #if defined(INTERP_ATTRIBS)
262 const GLfloat invLen = 1.0F / numPixels;
263 const GLfloat invw0 = vert0->attrib[FRAG_ATTRIB_WPOS][3];
264 const GLfloat invw1 = vert1->attrib[FRAG_ATTRIB_WPOS][3];
266 span.attrStart[FRAG_ATTRIB_WPOS][3] = invw0;
267 span.attrStepX[FRAG_ATTRIB_WPOS][3] = (invw1 - invw0) * invLen;
268 span.attrStepY[FRAG_ATTRIB_WPOS][3] = 0.0;
271 if (swrast->_InterpMode[attr] == GL_FLAT) {
272 COPY_4V(span.attrStart[attr], vert1->attrib[attr]);
273 ASSIGN_4V(span.attrStepX[attr], 0.0, 0.0, 0.0, 0.0);
277 for (c = 0; c < 4; c++) {
279 span.attrStart[attr][c] = invw0 * vert0->attrib[attr][c];
280 da = (invw1 * vert1->attrib[attr][c]) - span.attrStart[attr][c];
281 span.attrStepX[attr][c] = da * invLen;
284 ASSIGN_4V(span.attrStepY[attr], 0.0, 0.0, 0.0, 0.0);
289 INIT_SPAN(span, GL_LINE);
290 span.end = numPixels;
291 span.interpMask = interpFlags;
292 span.arrayMask = SPAN_XY;
294 span.facing = swrast->PointLineFacing;
302 /*** X-major line ***/
304 GLint errorInc = dy+dy;
305 GLint error = errorInc-dx;
306 GLint errorDec = error-dx;
308 for (i = 0; i < dx; i++) {
310 GLuint Z = FixedToDepth(span.z);
315 span.array->x[i] = x0;
316 span.array->y[i] = y0;
320 zPtr = (DEPTH_TYPE *) ((GLubyte*) zPtr + zPtrXstep);
321 span.z += span.zStep;
324 pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelXstep);
333 zPtr = (DEPTH_TYPE *) ((GLubyte*) zPtr + zPtrYstep);
336 pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelYstep);
342 /*** Y-major line ***/
344 GLint errorInc = dx+dx;
345 GLint error = errorInc-dy;
346 GLint errorDec = error-dy;
350 GLuint Z = FixedToDepth(span.z);
355 span.array->x[i] = x0;
356 span.array->y[i] = y0;
360 zPtr = (DEPTH_TYPE *) ((GLubyte*) zPtr + zPtrYstep);
361 span.z += span.zStep;
364 pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelYstep);
373 zPtr = (DEPTH_TYPE *) ((GLubyte*) zPtr + zPtrXstep);
376 pixelPtr = (PIXEL_TYPE*) ((GLubyte*) pixelPtr + pixelXstep);
393 #undef INTERP_ATTRIBS