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simple line drawing code
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Brian
parent
c9527eae8e
commit
6378dc3ae3
1 changed files with 240 additions and 32 deletions
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@ -36,6 +36,9 @@
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#include "g_tile.h"
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/**
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* Triangle edge info
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*/
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struct edge {
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GLfloat dx; /* X(v1) - X(v0), used only during setup */
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GLfloat dy; /* Y(v1) - Y(v0), used only during setup */
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@ -46,9 +49,13 @@ struct edge {
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};
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/**
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* Triangle setup info (derived from prim_stage).
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* Also used for line drawing (taking some liberties).
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*/
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struct setup_stage {
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struct prim_stage stage;
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struct prim_stage stage; /**< This must be first */
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/* Vertices are just an array of floats making up each attribute in
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* turn. Currently fixed at 4 floats, but should change in time.
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* Codegen will help cope with this.
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@ -57,7 +64,7 @@ struct setup_stage {
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const struct vertex_header *vmid;
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const struct vertex_header *vmin;
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const struct vertex_header *vprovoke;
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struct edge ebot;
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struct edge etop;
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struct edge emaj;
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@ -190,20 +197,9 @@ static void flush_spans( struct setup_stage *setup )
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}
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/**
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* Do setup for line rasterization, then render the line.
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*/
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static void
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setup_line( struct prim_stage *stage,
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struct prim_header *header )
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{
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}
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static GLboolean setup_sort_vertices( struct setup_stage *setup,
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const struct prim_header *prim )
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{
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const struct vertex_header *v0 = prim->v[0];
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const struct vertex_header *v1 = prim->v[1];
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const struct vertex_header *v2 = prim->v[2];
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@ -310,11 +306,12 @@ static void const_coeff( struct setup_stage *setup,
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/**
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* Compute a0, dadx and dady for a linearly interpolated coefficient.
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* Compute a0, dadx and dady for a linearly interpolated coefficient,
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* for a triangle.
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*/
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static void linear_coeff( struct setup_stage *setup,
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GLuint slot,
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GLuint i)
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static void tri_linear_coeff( struct setup_stage *setup,
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GLuint slot,
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GLuint i)
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{
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GLfloat botda = setup->vmid->data[slot][i] - setup->vmin->data[slot][i];
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GLfloat majda = setup->vmax->data[slot][i] - setup->vmin->data[slot][i];
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@ -349,11 +346,12 @@ static void linear_coeff( struct setup_stage *setup,
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/**
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* Compute a0, dadx and dady for a perspective-corrected interpolant.
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* Compute a0, dadx and dady for a perspective-corrected interpolant,
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* for a triangle.
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*/
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static void persp_coeff( struct setup_stage *setup,
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GLuint slot,
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GLuint i )
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static void tri_persp_coeff( struct setup_stage *setup,
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GLuint slot,
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GLuint i )
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{
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/* premultiply by 1/w:
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*/
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@ -379,15 +377,15 @@ static void persp_coeff( struct setup_stage *setup,
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* Compute the setup->coef[] array dadx, dady, a0 values.
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* Must be called after setup->vmin,vmid,vmax,vprovoke are initialized.
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*/
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static void setup_coefficients( struct setup_stage *setup )
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static void setup_tri_coefficients( struct setup_stage *setup )
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{
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const enum interp_mode *interp = setup->stage.generic->interp;
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GLuint slot, j;
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/* z and w are done by linear interpolation:
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*/
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linear_coeff(setup, 0, 2);
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linear_coeff(setup, 0, 3);
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tri_linear_coeff(setup, 0, 2);
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tri_linear_coeff(setup, 0, 3);
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/* setup interpolation for all the remaining attributes:
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*/
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@ -400,12 +398,12 @@ static void setup_coefficients( struct setup_stage *setup )
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case INTERP_LINEAR:
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for (j = 0; j < NUM_CHANNELS; j++)
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linear_coeff(setup, slot, j);
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tri_linear_coeff(setup, slot, j);
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break;
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case INTERP_PERSPECTIVE:
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for (j = 0; j < NUM_CHANNELS; j++)
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persp_coeff(setup, slot, j);
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tri_persp_coeff(setup, slot, j);
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break;
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}
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}
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@ -413,7 +411,7 @@ static void setup_coefficients( struct setup_stage *setup )
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static void setup_edges( struct setup_stage *setup )
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static void setup_tri_edges( struct setup_stage *setup )
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{
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GLfloat vmin_x = setup->vmin->data[0][0] + 0.5;
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GLfloat vmid_x = setup->vmid->data[0][0] + 0.5;
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@ -531,8 +529,8 @@ static void setup_tri( struct prim_stage *stage,
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_mesa_printf("%s\n", __FUNCTION__ );
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setup_sort_vertices( setup, prim );
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setup_coefficients( setup );
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setup_edges( setup );
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setup_tri_coefficients( setup );
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setup_tri_edges( setup );
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setup->span.y = 0;
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setup->span.y_flags = 0;
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@ -559,14 +557,224 @@ static void setup_tri( struct prim_stage *stage,
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}
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/**
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* Compute a0, dadx and dady for a linearly interpolated coefficient,
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* for a line.
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*/
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static void
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line_linear_coeff(struct setup_stage *setup, GLuint slot, GLuint i)
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{
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const GLfloat dz = setup->vmax->data[slot][i] - setup->vmin->data[slot][i];
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const GLfloat dadx = dz * setup->emaj.dx * setup->oneoverarea;
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const GLfloat dady = dz * setup->emaj.dy * setup->oneoverarea;
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setup->coef[slot].dadx[i] = dadx;
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setup->coef[slot].dady[i] = dady;
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setup->coef[slot].a0[i]
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= (setup->vmin->data[slot][i] -
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(dadx * (setup->vmin->data[0][0] - 0.5) +
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dady * (setup->vmin->data[0][1] - 0.5)));
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}
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/**
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* Compute a0, dadx and dady for a perspective-corrected interpolant,
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* for a line.
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*/
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static void
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line_persp_coeff(struct setup_stage *setup, GLuint slot, GLuint i)
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{
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/* XXX to do */
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line_linear_coeff(setup, slot, i); /* XXX temporary */
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}
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/**
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* Compute the setup->coef[] array dadx, dady, a0 values.
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* Must be called after setup->vmin,vmax are initialized.
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*/
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static INLINE void
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setup_line_coefficients(struct setup_stage *setup, struct prim_header *prim)
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{
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const enum interp_mode *interp = setup->stage.generic->interp;
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GLuint slot, j;
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/* use setup->vmin, vmax to point to vertices */
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setup->vprovoke = prim->v[1];
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setup->vmin = prim->v[0];
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setup->vmax = prim->v[1];
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setup->emaj.dx = setup->vmax->data[0][0] - setup->vmin->data[0][0];
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setup->emaj.dy = setup->vmax->data[0][1] - setup->vmin->data[0][1];
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/* NOTE: this is not really 1/area */
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setup->oneoverarea = 1.0 / (setup->emaj.dx * setup->emaj.dx +
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setup->emaj.dy * setup->emaj.dy);
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/* z and w are done by linear interpolation:
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*/
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line_linear_coeff(setup, 0, 2);
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line_linear_coeff(setup, 0, 3);
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/* setup interpolation for all the remaining attributes:
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*/
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for (slot = 1; slot < setup->quad.nr_attrs; slot++) {
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switch (interp[slot]) {
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case INTERP_CONSTANT:
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for (j = 0; j < NUM_CHANNELS; j++)
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const_coeff(setup, slot, j);
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break;
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case INTERP_LINEAR:
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for (j = 0; j < NUM_CHANNELS; j++)
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line_linear_coeff(setup, slot, j);
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break;
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case INTERP_PERSPECTIVE:
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for (j = 0; j < NUM_CHANNELS; j++)
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line_persp_coeff(setup, slot, j);
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break;
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}
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}
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}
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/**
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* Plot a pixel in a line segment.
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*/
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static INLINE void
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plot(struct setup_stage *setup, GLint x, GLint y)
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{
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const GLint quadX = block(x);
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const GLint quadY = block(y);
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if ((quadX != setup->quad.x0 || quadY != setup->quad.y0)
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&& setup->quad.x0 != -1) {
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/* flush prev quad, start new quad */
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quad_shade(setup->stage.generic, &setup->quad);
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setup->quad.mask = 0x0;
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}
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setup->quad.x0 = quadX;
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setup->quad.y0 = quadY;
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if (x & 1) {
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if (y & 1)
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setup->quad.mask |= MASK_TOP_RIGHT;
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else
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setup->quad.mask |= MASK_BOTTOM_RIGHT;
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}
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else {
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if (y & 1)
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setup->quad.mask |= MASK_TOP_LEFT;
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else
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setup->quad.mask |= MASK_BOTTOM_LEFT;
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}
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}
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/**
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* Do setup for line rasterization, then render the line.
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* XXX single-pixel width, no stipple, etc
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* XXX no scissoring yet.
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*/
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static void
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setup_line(struct prim_stage *stage, struct prim_header *prim)
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{
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const struct vertex_header *v0 = prim->v[0];
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const struct vertex_header *v1 = prim->v[1];
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struct setup_stage *setup = setup_stage( stage );
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GLint x0 = (GLint) v0->data[0][0];
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GLint x1 = (GLint) v1->data[0][0];
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GLint y0 = (GLint) v0->data[0][1];
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GLint y1 = (GLint) v1->data[0][1];
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GLint dx = x1 - x0;
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GLint dy = y1 - y0;
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GLint xstep, ystep;
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if (dx == 0 && dy == 0)
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return;
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setup_line_coefficients(setup, prim);
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if (dx < 0) {
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dx = -dx; /* make positive */
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xstep = -1;
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}
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else {
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xstep = 1;
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}
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if (dy < 0) {
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dy = -dy; /* make positive */
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ystep = -1;
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}
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else {
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ystep = 1;
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}
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assert(dx >= 0);
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assert(dy >= 0);
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setup->quad.x0 = setup->quad.y0 = -1;
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setup->quad.mask = 0x0;
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if (dx > dy) {
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/*** X-major line ***/
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GLint i;
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const GLint errorInc = dy + dy;
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GLint error = errorInc - dx;
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const GLint errorDec = error - dx;
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for (i = 0; i < dx; i++) {
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plot(setup, x0, y0);
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x0 += xstep;
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if (error < 0) {
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error += errorInc;
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}
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else {
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error += errorDec;
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y0 += ystep;
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}
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}
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}
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else {
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/*** Y-major line ***/
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GLint i;
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const GLint errorInc = dx + dx;
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GLint error = errorInc - dy;
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const GLint errorDec = error - dy;
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for (i = 0; i < dy; i++) {
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plot(setup, x0, y0);
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y0 += ystep;
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if (error < 0) {
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error += errorInc;
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}
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else {
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error += errorDec;
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x0 += xstep;
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}
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}
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}
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/* draw final quad */
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if (setup->quad.mask) {
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quad_shade(setup->stage.generic, &setup->quad);
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}
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}
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/**
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* Do setup for point rasterization, then render the point.
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* Round or square points...
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* XXX could optimize a lot for 1-pixel points.
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*/
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static void
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setup_point( struct prim_stage *stage,
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struct prim_header *prim )
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setup_point(struct prim_stage *stage, struct prim_header *prim)
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{
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struct setup_stage *setup = setup_stage( stage );
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GLfloat halfSize = 7.3; /*XXX this is a vertex attrib */
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