diff options
| -rw-r--r-- | src/gallium/auxiliary/draw/draw_pipe_wide_point.c | 48 |
1 files changed, 36 insertions, 12 deletions
diff --git a/src/gallium/auxiliary/draw/draw_pipe_wide_point.c b/src/gallium/auxiliary/draw/draw_pipe_wide_point.c index 014d8c7346d..7d76a7dbf39 100644 --- a/src/gallium/auxiliary/draw/draw_pipe_wide_point.c +++ b/src/gallium/auxiliary/draw/draw_pipe_wide_point.c @@ -28,6 +28,30 @@ /* Authors: Keith Whitwell <[email protected]> */ +/** + * Notes on wide points and sprite mode: + * + * In wide point/sprite mode we effectively need to convert each incoming + * vertex into four outgoing vertices specifying the corners of a quad. + * Since we don't (yet) have geometry shaders, we have to handle this here + * in the draw module. + * + * For sprites, it also means that this is where we have to handle texcoords + * for the vertices of the quad. OpenGL's GL_COORD_REPLACE state specifies + * if/how enabled texcoords are automatically generated for sprites. We pass + * that info through gallium in the pipe_rasterizer_state::sprite_coord_mode + * array. + * + * Additionally, GLSL's gl_PointCoord fragment attribute has to be handled + * here as well. This is basically an additional texture/generic attribute + * that varies .x from 0 to 1 horizontally across the point and varies .y + * vertically from 0 to 1 down the sprite. + * + * With geometry shaders, the state tracker could create a GS to do + * most/all of this. + */ + + #include "util/u_math.h" #include "util/u_memory.h" #include "pipe/p_defines.h" @@ -52,7 +76,7 @@ struct widepoint_stage { int psize_slot; - int point_coord_fs_input; /**< input for pointcoord (and fog) */ + int point_coord_fs_input; /**< input for pointcoord */ }; @@ -64,8 +88,6 @@ widepoint_stage( struct draw_stage *stage ) } - - /** * Set the vertex texcoords for sprite mode. * Coords may be left untouched or set to a right-side-up or upside-down @@ -89,10 +111,12 @@ static void set_texcoords(const struct widepoint_stage *wide, } if (wide->point_coord_fs_input >= 0) { - /* put gl_PointCoord into extra vertex output's zw components */ - uint k = wide->stage.draw->extra_vp_outputs.slot; - v->data[k][2] = tc[0]; - v->data[k][3] = tc[1]; + /* put gl_PointCoord into the extra vertex slot */ + uint slot = wide->stage.draw->extra_vp_outputs.slot; + v->data[slot][0] = tc[0]; + v->data[slot][1] = tc[1]; + v->data[slot][2] = 0.0F; + v->data[slot][3] = 1.0F; } } @@ -182,10 +206,10 @@ static void widepoint_point( struct draw_stage *stage, static int -find_fog_input_attrib(struct draw_context *draw) +find_pntc_input_attrib(struct draw_context *draw) { - /* Scan the fragment program's input decls to find the fogcoord - * attribute. The z/w components will store the point coord. + /* Scan the fragment program's input decls to find the pointcoord + * attribute. The xy components will store the point coord. */ return 0; /* XXX fix this */ } @@ -229,8 +253,8 @@ static void widepoint_first_point( struct draw_stage *stage, } wide->num_texcoords = j; - /* find fragment shader PointCoord/Fog input */ - wide->point_coord_fs_input = find_fog_input_attrib(draw); + /* find fragment shader PointCoord input */ + wide->point_coord_fs_input = find_pntc_input_attrib(draw); /* setup extra vp output (point coord implemented as a texcoord) */ draw->extra_vp_outputs.semantic_name = TGSI_SEMANTIC_GENERIC; |