From 6378dc3ae302e8a69f482fd99a63a23d1a1730a1 Mon Sep 17 00:00:00 2001 From: Brian Date: Tue, 12 Jun 2007 08:47:49 -0600 Subject: simple line drawing code --- src/mesa/softpipe/generic/g_prim_setup.c | 272 +++++++++++++++++++++++++++---- 1 file changed, 240 insertions(+), 32 deletions(-) (limited to 'src/mesa') diff --git a/src/mesa/softpipe/generic/g_prim_setup.c b/src/mesa/softpipe/generic/g_prim_setup.c index 614fc16c7c..125d361b92 100644 --- a/src/mesa/softpipe/generic/g_prim_setup.c +++ b/src/mesa/softpipe/generic/g_prim_setup.c @@ -36,6 +36,9 @@ #include "g_tile.h" +/** + * Triangle edge info + */ struct edge { GLfloat dx; /* X(v1) - X(v0), used only during setup */ GLfloat dy; /* Y(v1) - Y(v0), used only during setup */ @@ -46,9 +49,13 @@ struct edge { }; +/** + * Triangle setup info (derived from prim_stage). + * Also used for line drawing (taking some liberties). + */ struct setup_stage { - struct prim_stage stage; - + struct prim_stage stage; /**< This must be first */ + /* Vertices are just an array of floats making up each attribute in * turn. Currently fixed at 4 floats, but should change in time. * Codegen will help cope with this. @@ -57,7 +64,7 @@ struct setup_stage { const struct vertex_header *vmid; const struct vertex_header *vmin; const struct vertex_header *vprovoke; - + struct edge ebot; struct edge etop; struct edge emaj; @@ -190,20 +197,9 @@ static void flush_spans( struct setup_stage *setup ) } -/** - * Do setup for line rasterization, then render the line. - */ -static void -setup_line( struct prim_stage *stage, - struct prim_header *header ) -{ -} - - static GLboolean setup_sort_vertices( struct setup_stage *setup, const struct prim_header *prim ) { - const struct vertex_header *v0 = prim->v[0]; const struct vertex_header *v1 = prim->v[1]; const struct vertex_header *v2 = prim->v[2]; @@ -310,11 +306,12 @@ static void const_coeff( struct setup_stage *setup, /** - * Compute a0, dadx and dady for a linearly interpolated coefficient. + * Compute a0, dadx and dady for a linearly interpolated coefficient, + * for a triangle. */ -static void linear_coeff( struct setup_stage *setup, - GLuint slot, - GLuint i) +static void tri_linear_coeff( struct setup_stage *setup, + GLuint slot, + GLuint i) { GLfloat botda = setup->vmid->data[slot][i] - setup->vmin->data[slot][i]; GLfloat majda = setup->vmax->data[slot][i] - setup->vmin->data[slot][i]; @@ -349,11 +346,12 @@ static void linear_coeff( struct setup_stage *setup, /** - * Compute a0, dadx and dady for a perspective-corrected interpolant. + * Compute a0, dadx and dady for a perspective-corrected interpolant, + * for a triangle. */ -static void persp_coeff( struct setup_stage *setup, - GLuint slot, - GLuint i ) +static void tri_persp_coeff( struct setup_stage *setup, + GLuint slot, + GLuint i ) { /* premultiply by 1/w: */ @@ -379,15 +377,15 @@ static void persp_coeff( struct setup_stage *setup, * Compute the setup->coef[] array dadx, dady, a0 values. * Must be called after setup->vmin,vmid,vmax,vprovoke are initialized. */ -static void setup_coefficients( struct setup_stage *setup ) +static void setup_tri_coefficients( struct setup_stage *setup ) { const enum interp_mode *interp = setup->stage.generic->interp; GLuint slot, j; /* z and w are done by linear interpolation: */ - linear_coeff(setup, 0, 2); - linear_coeff(setup, 0, 3); + tri_linear_coeff(setup, 0, 2); + tri_linear_coeff(setup, 0, 3); /* setup interpolation for all the remaining attributes: */ @@ -400,12 +398,12 @@ static void setup_coefficients( struct setup_stage *setup ) case INTERP_LINEAR: for (j = 0; j < NUM_CHANNELS; j++) - linear_coeff(setup, slot, j); + tri_linear_coeff(setup, slot, j); break; case INTERP_PERSPECTIVE: for (j = 0; j < NUM_CHANNELS; j++) - persp_coeff(setup, slot, j); + tri_persp_coeff(setup, slot, j); break; } } @@ -413,7 +411,7 @@ static void setup_coefficients( struct setup_stage *setup ) -static void setup_edges( struct setup_stage *setup ) +static void setup_tri_edges( struct setup_stage *setup ) { GLfloat vmin_x = setup->vmin->data[0][0] + 0.5; GLfloat vmid_x = setup->vmid->data[0][0] + 0.5; @@ -531,8 +529,8 @@ static void setup_tri( struct prim_stage *stage, _mesa_printf("%s\n", __FUNCTION__ ); setup_sort_vertices( setup, prim ); - setup_coefficients( setup ); - setup_edges( setup ); + setup_tri_coefficients( setup ); + setup_tri_edges( setup ); setup->span.y = 0; setup->span.y_flags = 0; @@ -559,14 +557,224 @@ static void setup_tri( struct prim_stage *stage, } + +/** + * Compute a0, dadx and dady for a linearly interpolated coefficient, + * for a line. + */ +static void +line_linear_coeff(struct setup_stage *setup, GLuint slot, GLuint i) +{ + const GLfloat dz = setup->vmax->data[slot][i] - setup->vmin->data[slot][i]; + const GLfloat dadx = dz * setup->emaj.dx * setup->oneoverarea; + const GLfloat dady = dz * setup->emaj.dy * setup->oneoverarea; + setup->coef[slot].dadx[i] = dadx; + setup->coef[slot].dady[i] = dady; + setup->coef[slot].a0[i] + = (setup->vmin->data[slot][i] - + (dadx * (setup->vmin->data[0][0] - 0.5) + + dady * (setup->vmin->data[0][1] - 0.5))); +} + + +/** + * Compute a0, dadx and dady for a perspective-corrected interpolant, + * for a line. + */ +static void +line_persp_coeff(struct setup_stage *setup, GLuint slot, GLuint i) +{ + /* XXX to do */ + line_linear_coeff(setup, slot, i); /* XXX temporary */ +} + + +/** + * Compute the setup->coef[] array dadx, dady, a0 values. + * Must be called after setup->vmin,vmax are initialized. + */ +static INLINE void +setup_line_coefficients(struct setup_stage *setup, struct prim_header *prim) +{ + const enum interp_mode *interp = setup->stage.generic->interp; + GLuint slot, j; + + /* use setup->vmin, vmax to point to vertices */ + setup->vprovoke = prim->v[1]; + setup->vmin = prim->v[0]; + setup->vmax = prim->v[1]; + + setup->emaj.dx = setup->vmax->data[0][0] - setup->vmin->data[0][0]; + setup->emaj.dy = setup->vmax->data[0][1] - setup->vmin->data[0][1]; + /* NOTE: this is not really 1/area */ + setup->oneoverarea = 1.0 / (setup->emaj.dx * setup->emaj.dx + + setup->emaj.dy * setup->emaj.dy); + + /* z and w are done by linear interpolation: + */ + line_linear_coeff(setup, 0, 2); + line_linear_coeff(setup, 0, 3); + + /* setup interpolation for all the remaining attributes: + */ + for (slot = 1; slot < setup->quad.nr_attrs; slot++) { + switch (interp[slot]) { + case INTERP_CONSTANT: + for (j = 0; j < NUM_CHANNELS; j++) + const_coeff(setup, slot, j); + break; + + case INTERP_LINEAR: + for (j = 0; j < NUM_CHANNELS; j++) + line_linear_coeff(setup, slot, j); + break; + + case INTERP_PERSPECTIVE: + for (j = 0; j < NUM_CHANNELS; j++) + line_persp_coeff(setup, slot, j); + break; + } + } +} + + +/** + * Plot a pixel in a line segment. + */ +static INLINE void +plot(struct setup_stage *setup, GLint x, GLint y) +{ + const GLint quadX = block(x); + const GLint quadY = block(y); + + if ((quadX != setup->quad.x0 || quadY != setup->quad.y0) + && setup->quad.x0 != -1) { + /* flush prev quad, start new quad */ + quad_shade(setup->stage.generic, &setup->quad); + setup->quad.mask = 0x0; + } + setup->quad.x0 = quadX; + setup->quad.y0 = quadY; + + if (x & 1) { + if (y & 1) + setup->quad.mask |= MASK_TOP_RIGHT; + else + setup->quad.mask |= MASK_BOTTOM_RIGHT; + } + else { + if (y & 1) + setup->quad.mask |= MASK_TOP_LEFT; + else + setup->quad.mask |= MASK_BOTTOM_LEFT; + } +} + + + +/** + * Do setup for line rasterization, then render the line. + * XXX single-pixel width, no stipple, etc + * XXX no scissoring yet. + */ +static void +setup_line(struct prim_stage *stage, struct prim_header *prim) +{ + const struct vertex_header *v0 = prim->v[0]; + const struct vertex_header *v1 = prim->v[1]; + struct setup_stage *setup = setup_stage( stage ); + + GLint x0 = (GLint) v0->data[0][0]; + GLint x1 = (GLint) v1->data[0][0]; + GLint y0 = (GLint) v0->data[0][1]; + GLint y1 = (GLint) v1->data[0][1]; + GLint dx = x1 - x0; + GLint dy = y1 - y0; + GLint xstep, ystep; + + if (dx == 0 && dy == 0) + return; + + setup_line_coefficients(setup, prim); + + if (dx < 0) { + dx = -dx; /* make positive */ + xstep = -1; + } + else { + xstep = 1; + } + + if (dy < 0) { + dy = -dy; /* make positive */ + ystep = -1; + } + else { + ystep = 1; + } + + assert(dx >= 0); + assert(dy >= 0); + + setup->quad.x0 = setup->quad.y0 = -1; + setup->quad.mask = 0x0; + + if (dx > dy) { + /*** X-major line ***/ + GLint i; + const GLint errorInc = dy + dy; + GLint error = errorInc - dx; + const GLint errorDec = error - dx; + + for (i = 0; i < dx; i++) { + plot(setup, x0, y0); + + x0 += xstep; + if (error < 0) { + error += errorInc; + } + else { + error += errorDec; + y0 += ystep; + } + } + } + else { + /*** Y-major line ***/ + GLint i; + const GLint errorInc = dx + dx; + GLint error = errorInc - dy; + const GLint errorDec = error - dy; + + for (i = 0; i < dy; i++) { + plot(setup, x0, y0); + + y0 += ystep; + + if (error < 0) { + error += errorInc; + } + else { + error += errorDec; + x0 += xstep; + } + } + } + + /* draw final quad */ + if (setup->quad.mask) { + quad_shade(setup->stage.generic, &setup->quad); + } +} + + /** * Do setup for point rasterization, then render the point. * Round or square points... * XXX could optimize a lot for 1-pixel points. */ static void -setup_point( struct prim_stage *stage, - struct prim_header *prim ) +setup_point(struct prim_stage *stage, struct prim_header *prim) { struct setup_stage *setup = setup_stage( stage ); GLfloat halfSize = 7.3; /*XXX this is a vertex attrib */ -- cgit v1.2.3