[Mesa-dev] [v4 PATCH 05/10] mesa: helper function for scissor box of gl_framebuffer

[Kevin Rogovin]

Add helper convenience function that intersects the scissor values
against a passed bounding box. In addition, to avoid replicated code,
make the function _mesa_scissor_bounding_box() use this new function.

v2:
 Split from patch "mesa:helper-conveniance functions for drivers to implement ARB_framebuffer_no_attachment".
 White space and long line fixes.

v3:
 No changes.

v4:
 No changes.


Signed-off-by: Kevin Rogovin <kevin.rogovin at intel.com>
---
 src/mesa/main/framebuffer.c | 63 +++++++++++++++++++++++++++++++--------------
 src/mesa/main/framebuffer.h |  5 ++++
 2 files changed, 48 insertions(+), 20 deletions(-)

diff --git a/src/mesa/main/framebuffer.c b/src/mesa/main/framebuffer.c
index c2cfb92..dd9e4bc 100644
--- a/src/mesa/main/framebuffer.c
+++ b/src/mesa/main/framebuffer.c
@@ -357,42 +357,38 @@ update_framebuffer_size(struct gl_context *ctx, struct gl_framebuffer *fb)
 }
 
 
+
 /**
- * Calculate the inclusive bounding box for the scissor of a specific viewport
+ * Given a bounding box, intersect the bounding box with the scissor of
+ * a specified vieport.
  *
  * \param ctx     GL context.
- * \param buffer  Framebuffer to be checked against
  * \param idx     Index of the desired viewport
  * \param bbox    Bounding box for the scissored viewport.  Stored as xmin,
  *                xmax, ymin, ymax.
- *
- * \warning This function assumes that the framebuffer dimensions are up to
- * date (e.g., update_framebuffer_size has been recently called on \c buffer).
- *
- * \sa _mesa_clip_to_region
  */
-void
-_mesa_scissor_bounding_box(const struct gl_context *ctx,
-                           const struct gl_framebuffer *buffer,
-                           unsigned idx, int *bbox)
+extern void
+_mesa_intersect_scissor_bounding_box(const struct gl_context *ctx,
+                                     unsigned idx, int *bbox)
 {
-   bbox[0] = 0;
-   bbox[2] = 0;
-   bbox[1] = buffer->Width;
-   bbox[3] = buffer->Height;
-
    if (ctx->Scissor.EnableFlags & (1u << idx)) {
+      int xmax, ymax;
+
+      xmax = ctx->Scissor.ScissorArray[idx].X
+        + ctx->Scissor.ScissorArray[idx].Width;
+      ymax = ctx->Scissor.ScissorArray[idx].Y
+        + ctx->Scissor.ScissorArray[idx].Height;
       if (ctx->Scissor.ScissorArray[idx].X > bbox[0]) {
          bbox[0] = ctx->Scissor.ScissorArray[idx].X;
       }
       if (ctx->Scissor.ScissorArray[idx].Y > bbox[2]) {
          bbox[2] = ctx->Scissor.ScissorArray[idx].Y;
       }
-      if (ctx->Scissor.ScissorArray[idx].X + ctx->Scissor.ScissorArray[idx].Width < bbox[1]) {
-         bbox[1] = ctx->Scissor.ScissorArray[idx].X + ctx->Scissor.ScissorArray[idx].Width;
+      if (xmax < bbox[1]) {
+         bbox[1] = xmax;
       }
-      if (ctx->Scissor.ScissorArray[idx].Y + ctx->Scissor.ScissorArray[idx].Height < bbox[3]) {
-         bbox[3] = ctx->Scissor.ScissorArray[idx].Y + ctx->Scissor.ScissorArray[idx].Height;
+      if (ymax < bbox[3]) {
+        bbox[3] = ymax;
       }
       /* finally, check for empty region */
       if (bbox[0] > bbox[1]) {
@@ -402,6 +398,33 @@ _mesa_scissor_bounding_box(const struct gl_context *ctx,
          bbox[2] = bbox[3];
       }
    }
+}
+
+/**
+ * Calculate the inclusive bounding box for the scissor of a specific viewport
+ *
+ * \param ctx     GL context.
+ * \param buffer  Framebuffer to be checked against
+ * \param idx     Index of the desired viewport
+ * \param bbox    Bounding box for the scissored viewport.  Stored as xmin,
+ *                xmax, ymin, ymax.
+ *
+ * \warning This function assumes that the framebuffer dimensions are up to
+ * date (e.g., update_framebuffer_size has been recently called on \c buffer).
+ *
+ * \sa _mesa_clip_to_region
+ */
+void
+_mesa_scissor_bounding_box(const struct gl_context *ctx,
+                           const struct gl_framebuffer *buffer,
+                           unsigned idx, int *bbox)
+{
+   bbox[0] = 0;
+   bbox[2] = 0;
+   bbox[1] = buffer->Width;
+   bbox[3] = buffer->Height;
+
+   _mesa_intersect_scissor_bounding_box(ctx, idx, bbox);
 
    assert(bbox[0] <= bbox[1]);
    assert(bbox[2] <= bbox[3]);
diff --git a/src/mesa/main/framebuffer.h b/src/mesa/main/framebuffer.h
index 8b2aa34..bb1f2ea 100644
--- a/src/mesa/main/framebuffer.h
+++ b/src/mesa/main/framebuffer.h
@@ -76,6 +76,10 @@ _mesa_scissor_bounding_box(const struct gl_context *ctx,
                            const struct gl_framebuffer *buffer,
                            unsigned idx, int *bbox);
 
+extern void
+_mesa_intersect_scissor_bounding_box(const struct gl_context *ctx,
+                                     unsigned idx, int *bbox);
+
 static inline  GLuint
 _mesa_geometric_width(const struct gl_framebuffer *buffer)
 {
@@ -83,6 +87,7 @@ _mesa_geometric_width(const struct gl_framebuffer *buffer)
       buffer->Width : buffer->DefaultGeometry.Width;
 }
 
+
 static inline  GLuint
 _mesa_geometric_height(const struct gl_framebuffer *buffer)
 {
-- 
1.9.1