Replace gl_framebuffer's _ColorReadBufferMask with _ColorReadBufferIndex,

Streamline the _mesa_update_framebuffer() function a bit.

src/mesa/main/buffers.c

@@ -273,48 +273,49 @@ draw_buffer_enum_to_bitmask(GLenum buffer)
 
 /**
  * Helper routine used by glReadBuffer.
- * Given a GLenum naming (a) color buffer(s), return the corresponding
- * bitmask of DD_* flags.
+ * Given a GLenum naming a color buffer, return the index of the corresponding
+ * renderbuffer (a BUFFER_* value).
+ * return -1 for an invalid buffer.
  */
-static GLbitfield
-read_buffer_enum_to_bitmask(GLenum buffer)
+static GLint
+read_buffer_enum_to_index(GLenum buffer)
 {
    switch (buffer) {
       case GL_FRONT:
-         return BUFFER_BIT_FRONT_LEFT;
+         return BUFFER_FRONT_LEFT;
       case GL_BACK:
-         return BUFFER_BIT_BACK_LEFT;
+         return BUFFER_BACK_LEFT;
       case GL_RIGHT:
-         return BUFFER_BIT_FRONT_RIGHT;
+         return BUFFER_FRONT_RIGHT;
       case GL_FRONT_RIGHT:
-         return BUFFER_BIT_FRONT_RIGHT;
+         return BUFFER_FRONT_RIGHT;
       case GL_BACK_RIGHT:
-         return BUFFER_BIT_BACK_RIGHT;
+         return BUFFER_BACK_RIGHT;
       case GL_BACK_LEFT:
-         return BUFFER_BIT_BACK_LEFT;
+         return BUFFER_BACK_LEFT;
       case GL_LEFT:
-         return BUFFER_BIT_FRONT_LEFT;
+         return BUFFER_FRONT_LEFT;
       case GL_FRONT_LEFT:
-         return BUFFER_BIT_FRONT_LEFT;
+         return BUFFER_FRONT_LEFT;
       case GL_AUX0:
-         return BUFFER_BIT_AUX0;
+         return BUFFER_AUX0;
       case GL_AUX1:
-         return BUFFER_BIT_AUX1;
+         return BUFFER_AUX1;
       case GL_AUX2:
-         return BUFFER_BIT_AUX2;
+         return BUFFER_AUX2;
       case GL_AUX3:
-         return BUFFER_BIT_AUX3;
+         return BUFFER_AUX3;
       case GL_COLOR_ATTACHMENT0_EXT:
-         return BUFFER_BIT_COLOR0;
+         return BUFFER_COLOR0;
       case GL_COLOR_ATTACHMENT1_EXT:
-         return BUFFER_BIT_COLOR1;
+         return BUFFER_COLOR1;
       case GL_COLOR_ATTACHMENT2_EXT:
-         return BUFFER_BIT_COLOR2;
+         return BUFFER_COLOR2;
       case GL_COLOR_ATTACHMENT3_EXT:
-         return BUFFER_BIT_COLOR3;
+         return BUFFER_COLOR3;
       default:
          /* error */
-         return BAD_MASK;
+         return -1;
    }
 }
 
@@ -526,7 +527,8 @@ void GLAPIENTRY
 _mesa_ReadBuffer(GLenum buffer)
 {
    struct gl_framebuffer *fb;
-   GLbitfield srcMask, supportedMask;
+   GLbitfield supportedMask;
+   GLint srcBuffer;
    GLuint bufferID;
    GET_CURRENT_CONTEXT(ctx);
    ASSERT_OUTSIDE_BEGIN_END_AND_FLUSH(ctx);
@@ -538,18 +540,18 @@ _mesa_ReadBuffer(GLenum buffer)
       _mesa_debug(ctx, "glReadBuffer %s\n", _mesa_lookup_enum_by_nr(buffer));
 
    if (bufferID > 0 && buffer == GL_NONE) {
-      /* legal! */
-      srcMask = 0x0;
+      /* This is legal for user-created framebuffer objects */
+      srcBuffer = -1;
    }
    else {
-      /* general case */
-      srcMask = read_buffer_enum_to_bitmask(buffer);
-      if (srcMask == BAD_MASK) {
+      /* general case / window-system framebuffer */
+      srcBuffer = read_buffer_enum_to_index(buffer);
+      if (srcBuffer == -1) {
          _mesa_error(ctx, GL_INVALID_ENUM, "glReadBuffer(buffer)");
          return;
       }
       supportedMask = supported_buffer_bitmask(ctx, bufferID);
-      if ((srcMask & supportedMask) == 0) {
+      if (((1 << srcBuffer) & supportedMask) == 0) {
          _mesa_error(ctx, GL_INVALID_OPERATION, "glReadBuffer(buffer)");
          return;
       }
@@ -559,7 +561,7 @@ _mesa_ReadBuffer(GLenum buffer)
       ctx->Pixel.ReadBuffer = buffer;
    }
    fb->ColorReadBuffer = buffer;
-   fb->_ColorReadBufferMask = srcMask;
+   fb->_ColorReadBufferIndex = srcBuffer;
 
    ctx->NewState |= _NEW_PIXEL;
 

src/mesa/main/framebuffer.c

@@ -106,7 +106,7 @@ _mesa_new_framebuffer(GLcontext *ctx, GLuint name)
       fb->ColorDrawBuffer[0] = GL_COLOR_ATTACHMENT0_EXT;
       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_COLOR0;
       fb->ColorReadBuffer = GL_COLOR_ATTACHMENT0_EXT;
-      fb->_ColorReadBufferMask = BUFFER_BIT_COLOR0;
+      fb->_ColorReadBufferIndex = BUFFER_COLOR0;
       fb->Delete = _mesa_destroy_framebuffer;
    }
    return fb;
@@ -134,13 +134,13 @@ _mesa_initialize_framebuffer(struct gl_framebuffer *fb, const GLvisual *visual)
       fb->ColorDrawBuffer[0] = GL_BACK;
       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_BACK_LEFT;
       fb->ColorReadBuffer = GL_BACK;
-      fb->_ColorReadBufferMask = BUFFER_BIT_BACK_LEFT;
+      fb->_ColorReadBufferIndex = BUFFER_BACK_LEFT;
    }
    else {
       fb->ColorDrawBuffer[0] = GL_FRONT;
       fb->_ColorDrawBufferMask[0] = BUFFER_BIT_FRONT_LEFT;
       fb->ColorReadBuffer = GL_FRONT;
-      fb->_ColorReadBufferMask = BUFFER_BIT_FRONT_LEFT;
+      fb->_ColorReadBufferIndex = BUFFER_FRONT_LEFT;
    }
 
    fb->Delete = _mesa_destroy_framebuffer;
@@ -357,24 +357,6 @@ _mesa_update_framebuffer_visual(struct gl_framebuffer *fb)
 }
 
 
-/**
- * Given a framebuffer and a buffer bit (like BUFFER_BIT_FRONT_LEFT), return
- * the corresponding renderbuffer.
- */
-static struct gl_renderbuffer *
-get_renderbuffer(struct gl_framebuffer *fb, GLbitfield bufferBit)
-{
-   GLuint index;
-   for (index = 0; index < BUFFER_COUNT; index++) {
-      if ((1 << index) == bufferBit) {
-         return fb->Attachment[index].Renderbuffer;
-      }
-   }
-   _mesa_problem(NULL, "Bad bufferBit in get_renderbuffer");
-   return NULL;
-}
-
-
 /**
  * Update state related to the current draw/read framebuffers.
  * Specifically, update these framebuffer fields:
@@ -396,7 +378,7 @@ _mesa_update_framebuffer(GLcontext *ctx)
       _mesa_test_framebuffer_completeness(ctx, fb);
 
    /*
-    * Update the list of drawing renderbuffer pointers.
+    * Update the list of color drawing renderbuffer pointers.
     * Later, when we're rendering we'll loop from 0 to _NumColorDrawBuffers
     * writing colors.  We need the inner loop here because
     * glDrawBuffer(GL_FRONT_AND_BACK) can specify writing to two or four
@@ -405,11 +387,11 @@ _mesa_update_framebuffer(GLcontext *ctx)
    for (output = 0; output < ctx->Const.MaxDrawBuffers; output++) {
       GLbitfield bufferMask = fb->_ColorDrawBufferMask[output];
       GLuint count = 0;
-      GLuint bufferBit;
-      /* for each bit that's set in the bufferMask... */
-      for (bufferBit = 1; bufferMask; bufferBit <<= 1) {
+      GLuint i;
+      for (i = 0; bufferMask && i < BUFFER_COUNT; i++) {
+         const GLuint bufferBit = 1 << i;
          if (bufferBit & bufferMask) {
-            struct gl_renderbuffer *rb = get_renderbuffer(fb, bufferBit);
+            struct gl_renderbuffer *rb = fb->Attachment[i].Renderbuffer;
             if (rb) {
                fb->_ColorDrawBuffers[output][count] = rb;
                count++;
@@ -424,13 +406,18 @@ _mesa_update_framebuffer(GLcontext *ctx)
    }
 
    /*
-    * Update the read renderbuffer pointer.
+    * Update the color read renderbuffer pointer.
     * Unlike the DrawBuffer, we can only read from one (or zero) color buffers.
     */
-   if (fb->_ColorReadBufferMask == 0x0)
+   if (fb->_ColorReadBufferIndex == -1) {
       fb->_ColorReadBuffer = NULL; /* legal! */
-   else
-      fb->_ColorReadBuffer = get_renderbuffer(fb, fb->_ColorReadBufferMask);
-
+   }
+   else {
+      ASSERT(fb->_ColorReadBufferIndex >= 0);
+      ASSERT(fb->_ColorReadBufferIndex < BUFFER_COUNT);
+      fb->_ColorReadBuffer
+         = fb->Attachment[fb->_ColorReadBufferIndex].Renderbuffer;
+      printf("Read buffer index %d\n", fb->_ColorReadBufferIndex);
+   }
    compute_depth_max(fb);
 }

src/mesa/main/mtypes.h

@@ -2198,7 +2198,7 @@ struct gl_framebuffer
 
    /* These are computed from ColorDrawBuffer and ColorReadBuffer */
    GLbitfield _ColorDrawBufferMask[MAX_DRAW_BUFFERS]; /* Mask of BUFFER_BIT_* flags */
-   GLbitfield _ColorReadBufferMask; /* Zero or one of BUFFER_BIT_ flags */
+   GLint _ColorReadBufferIndex; /* -1 = None */
 
    /* These are computed from _Draw/ReadBufferMask, above. */
    GLuint _NumColorDrawBuffers[MAX_DRAW_BUFFERS];