i965/gen6+: enable EXT_polygon_offset_clamp

Replace the hard-coded 0's with the context clamp value.

Signed-off-by: Ilia Mirkin <imirkin@alum.mit.edu>
Reviewed-by: Kenneth Graunke <kenneth@whitecape.org>

docs/relnotes/10.5.0.html

@@ -47,6 +47,7 @@ Note: some of the new features are only available with certain drivers.
 <li>GL_ARB_framebuffer_sRGB on freedreno</li>
 <li>GL_ARB_texture_rg on freedreno</li>
 <li>GL_EXT_packed_float on freedreno</li>
+<li>GL_EXT_polygon_offset_clamp on i965</li>
 <li>GL_EXT_texture_shared_exponent on freedreno</li>
 <li>GL_EXT_texture_snorm on freedreno</li>
 </ul>

src/mesa/drivers/dri/i965/gen6_sf_state.c

@@ -427,7 +427,7 @@ upload_sf_state(struct brw_context *brw)
    OUT_BATCH(dw4);
    OUT_BATCH_F(ctx->Polygon.OffsetUnits * 2); /* constant.  copied from gen4 */
    OUT_BATCH_F(ctx->Polygon.OffsetFactor); /* scale */
-   OUT_BATCH_F(0.0); /* XXX: global depth offset clamp */
+   OUT_BATCH_F(ctx->Polygon.OffsetClamp); /* global depth offset clamp */
    for (i = 0; i < 8; i++) {
       OUT_BATCH(attr_overrides[i * 2] | attr_overrides[i * 2 + 1] << 16);
    }

src/mesa/drivers/dri/i965/gen7_sf_state.c

@@ -242,7 +242,7 @@ upload_sf_state(struct brw_context *brw)
    OUT_BATCH(dw3);
    OUT_BATCH_F(ctx->Polygon.OffsetUnits * 2); /* constant.  copied from gen4 */
    OUT_BATCH_F(ctx->Polygon.OffsetFactor); /* scale */
-   OUT_BATCH_F(0.0); /* XXX: global depth offset clamp */
+   OUT_BATCH_F(ctx->Polygon.OffsetClamp); /* global depth offset clamp */
    ADVANCE_BATCH();
 }
 

src/mesa/drivers/dri/i965/gen8_sf_state.c

@@ -314,7 +314,7 @@ upload_raster(struct brw_context *brw)
    OUT_BATCH(dw1);
    OUT_BATCH_F(ctx->Polygon.OffsetUnits * 2); /* constant.  copied from gen4 */
    OUT_BATCH_F(ctx->Polygon.OffsetFactor); /* scale */
-   OUT_BATCH_F(0.0);
+   OUT_BATCH_F(ctx->Polygon.OffsetClamp); /* global depth offset clamp */
    ADVANCE_BATCH();
 }
 

src/mesa/drivers/dri/i965/intel_extensions.c

@@ -285,6 +285,7 @@ intelInitExtensions(struct gl_context *ctx)
       ctx->Extensions.ARB_texture_gather = true;
       ctx->Extensions.ARB_conditional_render_inverted = true;
       ctx->Extensions.AMD_vertex_shader_layer = true;
+      ctx->Extensions.EXT_polygon_offset_clamp = true;
 
       /* Test if the kernel has the ioctl. */
       if (drm_intel_reg_read(brw->bufmgr, TIMESTAMP, &dummy) == 0)