[Mesa-dev] [PATCH 36/37] i965: Enable ARB_viewport_array

[Ian Romanick]

From: Courtney Goeltzenleuchter <courtney at LunarG.com>

v2 (idr): Only enable the extension on GEN7+ w/core profile because it
requires geometry shaders.

v3 (idr): Add some casting to fix setting of ViewportBounds.Min.
Negating an unsigned value, then casting to float doesn't do what you
might think it does.

Signed-off-by: Courtney Goeltzenleuchter <courtney at LunarG.com>
Signed-off-by: Ian Romanick <ian.d.romanick at intel.com>
Reviewed-by: Kenneth Graunke <kenneth at whitecape.org>
---
 src/mesa/drivers/dri/i965/brw_context.c      | 11 +++++++++++
 src/mesa/drivers/dri/i965/intel_extensions.c |  6 ++++++
 2 files changed, 17 insertions(+)

diff --git a/src/mesa/drivers/dri/i965/brw_context.c b/src/mesa/drivers/dri/i965/brw_context.c
index 51918b9..7227c58 100644
--- a/src/mesa/drivers/dri/i965/brw_context.c
+++ b/src/mesa/drivers/dri/i965/brw_context.c
@@ -474,6 +474,17 @@ brw_initialize_context_constants(struct brw_context *brw)
    }
 
    ctx->ShaderCompilerOptions[MESA_SHADER_VERTEX].PreferDP4 = true;
+
+   /* ARB_viewport_array */
+   if (brw->gen >= 7 && ctx->API == API_OPENGL_CORE) {
+      ctx->Const.MaxViewports = GEN7_NUM_VIEWPORTS;
+      ctx->Const.ViewportSubpixelBits = 0;
+
+      /* Cast to float before negating becuase MaxViewportWidth is unsigned.
+       */
+      ctx->Const.ViewportBounds.Min = -(float)ctx->Const.MaxViewportWidth;
+      ctx->Const.ViewportBounds.Max = ctx->Const.MaxViewportWidth;
+   }
 }
 
 /**
diff --git a/src/mesa/drivers/dri/i965/intel_extensions.c b/src/mesa/drivers/dri/i965/intel_extensions.c
index f3dc823..ab73434 100644
--- a/src/mesa/drivers/dri/i965/intel_extensions.c
+++ b/src/mesa/drivers/dri/i965/intel_extensions.c
@@ -294,6 +294,12 @@ intelInitExtensions(struct gl_context *ctx)
          ctx->Extensions.ARB_transform_feedback_instanced = true;
          ctx->Extensions.ARB_draw_indirect = true;
       }
+
+      /* Only enable this in core profile because other parts of Mesa behave
+       * slightly differently when the extension is enabled.
+       */
+      if (ctx->API == API_OPENGL_CORE)
+         ctx->Extensions.ARB_viewport_array = true;
    }
 
    if (brw->gen == 5 || can_write_oacontrol(brw))
-- 
1.8.1.4