radeonsi: do per-pixel clipping based on viewport states

In other words, vport scissors are derived from viewport states.
If the scissor test is enabled, the intersection of both is used.

The guard band will disable clipping, so we have to clip per-pixel.

Reviewed-by: Nicolai Hähnle <[email protected]>

2 files changed, 85 insertions, 11 deletions

diff --git a/src/gallium/drivers/radeonsi/si_state.c b/src/gallium/drivers/radeonsi/si_state.c
index 057458c843a..8087d2331ff 100644
--- a/src/gallium/drivers/radeonsi/si_state.c
+++ b/src/gallium/drivers/radeonsi/si_state.c
@@ -830,25 +830,93 @@ static void si_set_scissor_states(struct pipe_context *ctx,
 	for (i = 0; i < num_scissors; i++)
 		sctx->scissors.states[start_slot + i] = state[i];
 
+	if (!sctx->queued.named.rasterizer ||
+	    !sctx->queued.named.rasterizer->scissor_enable)
+		return;
+
 	sctx->scissors.dirty_mask |= ((1 << num_scissors) - 1) << start_slot;
 	si_mark_atom_dirty(sctx, &sctx->scissors.atom);
 }
 
+static void si_get_scissor_from_viewport(struct pipe_viewport_state *vp,
+					 struct pipe_scissor_state *scissor)
+{
+	/* These must be signed, unlike pipe_scissor_state. */
+	int minx, miny, maxx, maxy, tmp;
+
+	/* Convert (-1, -1) and (1, 1) from clip space into window space. */
+	minx = -vp->scale[0] + vp->translate[0];
+	miny = -vp->scale[1] + vp->translate[1];
+	maxx = vp->scale[0] + vp->translate[0];
+	maxy = vp->scale[1] + vp->translate[1];
+
+	/* r600_draw_rectangle sets this. Disable the scissor. */
+	if (minx == -1 && miny == -1 && maxx == 1 && maxy == 1) {
+		minx = miny = 0;
+		maxx = maxy = 16384;
+	}
+
+	/* Handle inverted viewports. */
+	if (minx > maxx) {
+		tmp = minx;
+		minx = maxx;
+		maxx = tmp;
+	}
+	if (miny > maxy) {
+		tmp = miny;
+		miny = maxy;
+		maxy = tmp;
+	}
+
+	scissor->minx = CLAMP(minx, 0, 16384);
+	scissor->miny = CLAMP(miny, 0, 16384);
+	scissor->maxx = CLAMP(maxx, 0, 16384);
+	scissor->maxy = CLAMP(maxy, 0, 16384);
+}
+
+static void si_clip_scissor(struct pipe_scissor_state *out,
+			    struct pipe_scissor_state *clip)
+{
+	out->minx = MAX2(out->minx, clip->minx);
+	out->miny = MAX2(out->miny, clip->miny);
+	out->maxx = MIN2(out->maxx, clip->maxx);
+	out->maxy = MIN2(out->maxy, clip->maxy);
+}
+
+static void si_emit_one_scissor(struct radeon_winsys_cs *cs,
+				struct pipe_viewport_state *vp,
+				struct pipe_scissor_state *scissor)
+{
+	struct pipe_scissor_state final;
+
+	/* Since the guard band disables clipping, we have to clip per-pixel
+	 * using a scissor.
+	 */
+	si_get_scissor_from_viewport(vp, &final);
+
+	if (scissor)
+		si_clip_scissor(&final, scissor);
+
+	radeon_emit(cs, S_028250_TL_X(final.minx) |
+			S_028250_TL_Y(final.miny) |
+			S_028250_WINDOW_OFFSET_DISABLE(1));
+	radeon_emit(cs, S_028254_BR_X(final.maxx) |
+			S_028254_BR_Y(final.maxy));
+}
+
 static void si_emit_scissors(struct si_context *sctx, struct r600_atom *atom)
 {
 	struct radeon_winsys_cs *cs = sctx->b.gfx.cs;
 	struct pipe_scissor_state *states = sctx->scissors.states;
 	unsigned mask = sctx->scissors.dirty_mask;
+	bool scissor_enable = sctx->queued.named.rasterizer->scissor_enable;
 
 	/* The simple case: Only 1 viewport is active. */
 	if (mask & 1 &&
 	    !si_get_vs_info(sctx)->writes_viewport_index) {
 		radeon_set_context_reg_seq(cs, R_028250_PA_SC_VPORT_SCISSOR_0_TL, 2);
-		radeon_emit(cs, S_028250_TL_X(states[0].minx) |
-				S_028250_TL_Y(states[0].miny) |
-				S_028250_WINDOW_OFFSET_DISABLE(1));
-		radeon_emit(cs, S_028254_BR_X(states[0].maxx) |
-				S_028254_BR_Y(states[0].maxy));
+		si_emit_one_scissor(cs, &sctx->viewports.states[0],
+				    scissor_enable ? &states[0] : NULL);
 		sctx->scissors.dirty_mask &= ~1; /* clear one bit */
 		return;
 	}
@@ -861,11 +929,8 @@ static void si_emit_scissors(struct si_context *sctx, struct r600_atom *atom)
 		radeon_set_context_reg_seq(cs, R_028250_PA_SC_VPORT_SCISSOR_0_TL +
 					       start * 4 * 2, count * 2);
 		for (i = start; i < start+count; i++) {
-			radeon_emit(cs, S_028250_TL_X(states[i].minx) |
-					S_028250_TL_Y(states[i].miny) |
-					S_028250_WINDOW_OFFSET_DISABLE(1));
-			radeon_emit(cs, S_028254_BR_X(states[i].maxx) |
-					S_028254_BR_Y(states[i].maxy));
+			si_emit_one_scissor(cs, &sctx->viewports.states[i],
+					    scissor_enable ? &states[i] : NULL);
 		}
 	}
 	sctx->scissors.dirty_mask = 0;
@@ -883,7 +948,9 @@ static void si_set_viewport_states(struct pipe_context *ctx,
 		sctx->viewports.states[start_slot + i] = state[i];
 
 	sctx->viewports.dirty_mask |= ((1 << num_viewports) - 1) << start_slot;
+	sctx->scissors.dirty_mask |= ((1 << num_viewports) - 1) << start_slot;
 	si_mark_atom_dirty(sctx, &sctx->viewports.atom);
+	si_mark_atom_dirty(sctx, &sctx->scissors.atom);
 }
 
 static void si_emit_viewports(struct si_context *sctx, struct r600_atom *atom)
@@ -980,6 +1047,7 @@ static void *si_create_rs_state(struct pipe_context *ctx,
 		return NULL;
 	}
 
+	rs->scissor_enable = state->scissor;
 	rs->two_side = state->light_twoside;
 	rs->multisample_enable = state->multisample;
 	rs->force_persample_interp = state->force_persample_interp;
@@ -1038,7 +1106,7 @@ static void *si_create_rs_state(struct pipe_context *ctx,
 		       S_028A48_MSAA_ENABLE(state->multisample ||
 					    state->poly_smooth ||
 					    state->line_smooth) |
-		       S_028A48_VPORT_SCISSOR_ENABLE(state->scissor));
+		       S_028A48_VPORT_SCISSOR_ENABLE(1));
 
 	si_pm4_set_reg(pm4, R_028BE4_PA_SU_VTX_CNTL,
 		       S_028BE4_PIX_CENTER(state->half_pixel_center) |
@@ -1105,6 +1173,11 @@ static void si_bind_rs_state(struct pipe_context *ctx, void *state)
 	    (!old_rs || old_rs->multisample_enable != rs->multisample_enable))
 		si_mark_atom_dirty(sctx, &sctx->db_render_state);
 
+	if (!old_rs || old_rs->scissor_enable != rs->scissor_enable) {
+		sctx->scissors.dirty_mask = (1 << SI_MAX_VIEWPORTS) - 1;
+		si_mark_atom_dirty(sctx, &sctx->scissors.atom);
+	}
+
 	si_pm4_bind_state(sctx, rasterizer, rs);
 	si_update_poly_offset_state(sctx);
 
diff --git a/src/gallium/drivers/radeonsi/si_state.h b/src/gallium/drivers/radeonsi/si_state.h
index bec99e15efa..f55f19e2918 100644
--- a/src/gallium/drivers/radeonsi/si_state.h
+++ b/src/gallium/drivers/radeonsi/si_state.h
@@ -68,6 +68,7 @@ struct si_state_rasterizer {
 	bool			uses_poly_offset;
 	bool			clamp_fragment_color;
 	bool			rasterizer_discard;
+	bool			scissor_enable;
 };
 
 struct si_dsa_stencil_ref_part {