Implement software fallback for render-to-texture when the texture format

can't be rendered by the hardware.

src/mesa/drivers/dri/i915/intel_buffers.c

@@ -384,11 +384,11 @@ static void intelClear(GLcontext *ctx,
    GLbitfield tri_mask = 0;
    GLbitfield blit_mask = 0;
    GLbitfield swrast_mask = 0;
+   GLuint i;
 
    if (0)
       fprintf(stderr, "%s\n", __FUNCTION__);
 
-
    /* HW color buffers (front, back, aux, generic FBO, etc) */
    if (colorMask == ~0) {
       /* clear all R,G,B,A */
@@ -429,6 +429,18 @@ static void intelClear(GLcontext *ctx,
    /* SW fallback clearing */
    swrast_mask = mask & ~tri_mask & ~blit_mask;
 
+   for (i = 0; i < BUFFER_COUNT; i++) {
+      GLuint bufBit = 1 << i;
+      if ((blit_mask | tri_mask) & bufBit) {
+         if (!ctx->DrawBuffer->Attachment[i].Renderbuffer->ClassID) {
+            blit_mask &= ~bufBit;
+            tri_mask &= ~bufBit;
+            swrast_mask |= bufBit;
+         }
+      }
+   }
+
+
    intelFlush( ctx ); /* XXX intelClearWithBlit also does this */
 
    if (blit_mask)
@@ -603,6 +615,13 @@ intel_draw_buffer(GLcontext *ctx, struct gl_framebuffer *fb)
       colorRegion = (irb && irb->region) ? irb->region : NULL;
    }
 
+   if (!colorRegion) {
+      FALLBACK( intel, INTEL_FALLBACK_DRAW_BUFFER, GL_TRUE );
+   }
+   else {
+      FALLBACK( intel, INTEL_FALLBACK_DRAW_BUFFER, GL_FALSE );
+   }
+
    /***
     *** Get depth buffer region and check if we need a software fallback.
     *** Note that the depth buffer is usually a DEPTH_STENCIL buffer.

src/mesa/drivers/dri/i915/intel_fbo.c

@@ -120,29 +120,15 @@ intel_delete_renderbuffer(struct gl_renderbuffer *rb)
 
 /**
  * Return a pointer to a specific pixel in a renderbuffer.
- * Note: y=0=bottom.
- * Called via gl_renderbuffer::GetPointer().
  */
 static void *
 intel_get_pointer(GLcontext *ctx, struct gl_renderbuffer *rb,
                   GLint x, GLint y)
 {
-   struct intel_renderbuffer *irb = intel_renderbuffer(rb);
-
-   /* Actually, we could _always_ return NULL from this function and
-    * be OK.  The swrast code would just use the Get/Put routines as needed.
-    * But by really implementing this function there's a chance for better
-    * performance.
+   /* By returning NULL we force all software rendering to go through
+    * the span routines.
     */
-   if (irb->region && irb->region->map) {
-      int offset;
-      y = irb->region->height - y - 1;
-      offset = (y * irb->region->pitch + x) * irb->region->cpp;
-      return (void *) (irb->region->map + offset);
-   }
-   else {
-      return NULL;
-   }
+   return NULL;
 }
 
 
@@ -572,9 +558,7 @@ intel_renderbuffer_texture(GLcontext *ctx,
       }
       else {
          /* fallback to software rendering */
-         _mesa_problem(ctx, "Render to texture - unsupported hw format");
          _mesa_renderbuffer_texture(ctx, fb, att);
-         /* XXX FBO: Need to map the buffer (or in intelSpanRenderStart???) */
          return;
       }
    }

src/mesa/drivers/dri/i915/intel_span.c

@@ -172,6 +172,11 @@
  * XXX in the future, we could probably convey extra information to
  * reduce the number of mappings needed.  I.e. if doing a glReadPixels
  * from the depth buffer, we really only need one mapping.
+ *
+ * XXX Rewrite this function someday.
+ * We can probably just loop over all the renderbuffer attachments,
+ * map/unmap all of them, and not worry about the _ColorDrawBuffers
+ * _ColorReadBuffer, _DepthBuffer or _StencilBuffer fields.
  */
 static void
 intel_map_unmap_buffers(struct intel_context *intel, GLboolean map)
@@ -185,9 +190,8 @@ intel_map_unmap_buffers(struct intel_context *intel, GLboolean map)
       for (j = 0; j < ctx->DrawBuffer->_NumColorDrawBuffers[i]; j++) {
          struct gl_renderbuffer *rb = ctx->DrawBuffer->_ColorDrawBuffers[i][j];
          irb = intel_renderbuffer(rb);
-         /* XXX FBO: check irb != NULL to catch software RBs??? */
-         ASSERT(irb);
-         if (irb->Base.Name != 0) { /* XXX FBO temporary test */
+         if (irb && irb->Base.Name != 0) { /* XXX FBO temporary test */
+            /* this is a user-created intel_renderbuffer */
             if (irb->region) {
                if (map)
                   intel_region_map(intel, irb->region);
@@ -200,6 +204,24 @@ intel_map_unmap_buffers(struct intel_context *intel, GLboolean map)
       }
    }
 
+   /* check for render to textures */
+   for (i = 0; i < BUFFER_COUNT; i++) {
+      struct gl_renderbuffer_attachment *att = ctx->DrawBuffer->Attachment + i;
+      struct gl_texture_object *tex = att->Texture;
+      if (tex) {
+         /* render to texture */
+         ASSERT(att->Renderbuffer);
+         if (map) {
+            struct gl_texture_image *texImg;
+            texImg = tex->Image[att->CubeMapFace][att->TextureLevel];
+            intel_tex_map_images(intel, intel_texture_object(tex));
+         }
+         else {
+            intel_tex_unmap_images(intel, intel_texture_object(tex));
+         }
+      }
+   }
+
    /* color read buffers */
    irb = intel_renderbuffer(ctx->ReadBuffer->_ColorReadBuffer);
    if (irb && irb->region && irb->Base.Name != 0) {
@@ -242,10 +264,16 @@ intel_map_unmap_buffers(struct intel_context *intel, GLboolean map)
    if (ctx->DrawBuffer->_DepthBuffer) {
       irb = intel_renderbuffer(ctx->DrawBuffer->_DepthBuffer->Wrapped);
       if (irb && irb->region && irb->Base.Name != 0) {
-         if (map)
+         if (map) {
             intel_region_map(intel, irb->region);
-         else
+            irb->pfMap = irb->region->map;
+            irb->pfPitch = irb->region->pitch;
+         }
+         else {
             intel_region_unmap(intel, irb->region);
+            irb->pfMap = NULL;
+            irb->pfPitch = 0;
+         }
       }
    }
 
@@ -253,10 +281,16 @@ intel_map_unmap_buffers(struct intel_context *intel, GLboolean map)
    if (ctx->DrawBuffer->_StencilBuffer) {
       irb = intel_renderbuffer(ctx->DrawBuffer->_StencilBuffer->Wrapped);
       if (irb && irb->region && irb->Base.Name != 0) {
-         if (map)
+         if (map) {
             intel_region_map(intel, irb->region);
-         else
+            irb->pfMap = irb->region->map;
+            irb->pfPitch = irb->region->pitch;
+         }
+         else {
             intel_region_unmap(intel, irb->region);
+            irb->pfMap = NULL;
+            irb->pfPitch = 0;
+         }
       }
    }
 }