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authorBrian <brian.paul@tungstengraphics.com>2008-02-12 19:14:58 -0700
committerBrian <brian.paul@tungstengraphics.com>2008-02-12 19:14:58 -0700
commite20e89e48287808068086ec148920dd89495d813 (patch)
treea94c73460a26791bd5fde4e58465bac673557aae /src
parent9af687c53037afe57e765f705906e12a86865c03 (diff)
gallium: initial code for wide/AA line drawing
Diffstat (limited to 'src')
-rw-r--r--src/mesa/pipe/draw/draw_wide_prims.c75
1 files changed, 69 insertions, 6 deletions
diff --git a/src/mesa/pipe/draw/draw_wide_prims.c b/src/mesa/pipe/draw/draw_wide_prims.c
index 9759e7e2e8..4c7e279b20 100644
--- a/src/mesa/pipe/draw/draw_wide_prims.c
+++ b/src/mesa/pipe/draw/draw_wide_prims.c
@@ -76,7 +76,6 @@ static void passthrough_tri( struct draw_stage *stage,
/**
* Draw a wide line by drawing a quad (two triangles).
- * XXX still need line stipple.
* XXX need to disable polygon stipple.
*/
static void wide_line( struct draw_stage *stage,
@@ -103,12 +102,9 @@ static void wide_line( struct draw_stage *stage,
/*
* Draw wide line as a quad (two tris) by "stretching" the line along
* X or Y.
- * XXX For AA lines, the quad corners have to be computed in a
- * more sophisticated way.
+ * We need to tweak coords in several ways to be conformant here.
*/
- /* need to tweak coords in several ways to be conformant here */
-
if (dx > dy) {
/* x-major line */
pos0[1] = pos0[1] - half_width - 0.25f;
@@ -166,6 +162,70 @@ static void wide_line( struct draw_stage *stage,
/**
+ * Draw a wide line by drawing a quad, using geometry which will
+ * fullfill GL's antialiased line requirements.
+ */
+static void wide_line_aa(struct draw_stage *stage,
+ struct prim_header *header)
+{
+ const struct wide_stage *wide = wide_stage(stage);
+ const float half_width = wide->half_line_width;
+ struct prim_header tri;
+ struct vertex_header *v[4];
+ float *pos;
+ float dx = header->v[1]->data[0][0] - header->v[0]->data[0][0];
+ float dy = header->v[1]->data[0][1] - header->v[0]->data[0][1];
+ const float len = sqrt(dx * dx + dy * dy);
+ uint i;
+
+ dx = dx * half_width / len;
+ dy = dy * half_width / len;
+
+ /* allocate/dup new verts */
+ for (i = 0; i < 4; i++) {
+ v[i] = dup_vert(stage, header->v[i/2], i);
+ }
+
+ /*
+ * Quad for line from v0 to v1:
+ *
+ * 1 3
+ * +-------------------------+
+ * | |
+ * *v0 v1*
+ * | |
+ * +-------------------------+
+ * 0 2
+ */
+
+ pos = v[0]->data[0];
+ pos[0] += dy;
+ pos[1] -= dx;
+
+ pos = v[1]->data[0];
+ pos[0] -= dy;
+ pos[1] += dx;
+
+ pos = v[2]->data[0];
+ pos[0] += dy;
+ pos[1] -= dx;
+
+ pos = v[3]->data[0];
+ pos[0] -= dy;
+ pos[1] += dx;
+
+ tri.det = header->det; /* only the sign matters */
+
+ tri.v[0] = v[2]; tri.v[1] = v[1]; tri.v[2] = v[0];
+ stage->next->tri( stage->next, &tri );
+
+ tri.v[0] = v[3]; tri.v[1] = v[1]; tri.v[2] = v[2];
+ stage->next->tri( stage->next, &tri );
+
+}
+
+
+/**
* Set the vertex texcoords for sprite mode.
* Coords may be left untouched or set to a right-side-up or upside-down
* orientation.
@@ -319,7 +379,10 @@ static void wide_first_line( struct draw_stage *stage,
wide->half_line_width = 0.5f * draw->rasterizer->line_width;
if (draw->rasterizer->line_width != 1.0) {
- wide->stage.line = wide_line;
+ if (draw->rasterizer->line_smooth)
+ wide->stage.line = wide_line_aa;
+ else
+ wide->stage.line = wide_line;
}
else {
wide->stage.line = passthrough_line;