+
+/**
+ * Combine depth texture mode with "swizzle" so that depth mode swizzling
+ * takes place before texture swizzling, and return the resulting swizzle.
+ * If the format is not a depth format, return "swizzle" unchanged.
+ *
+ * \param format PIPE_FORMAT_*.
+ * \param swizzle Texture swizzle, a bitmask computed using MAKE_SWIZZLE4.
+ * \param depthmode One of GL_LUMINANCE, GL_INTENSITY, GL_ALPHA, GL_RED.
+ */
+static GLuint
+apply_depthmode(enum pipe_format format, GLuint swizzle, GLenum depthmode)
+{
+ const struct util_format_description *desc =
+ util_format_description(format);
+ unsigned char swiz[4];
+ unsigned i;
+
+ if (desc->colorspace != UTIL_FORMAT_COLORSPACE_ZS ||
+ desc->swizzle[0] == UTIL_FORMAT_SWIZZLE_NONE) {
+ /* Not a depth format. */
+ return swizzle;
+ }
+
+ for (i = 0; i < 4; i++)
+ swiz[i] = GET_SWZ(swizzle, i);
+
+ switch (depthmode) {
+ case GL_LUMINANCE:
+ /* Rewrite reads from W to ONE, and reads from XYZ to XXX. */
+ for (i = 0; i < 4; i++)
+ if (swiz[i] == SWIZZLE_W)
+ swiz[i] = SWIZZLE_ONE;
+ else if (swiz[i] < SWIZZLE_W)
+ swiz[i] = SWIZZLE_X;
+ break;
+
+ case GL_INTENSITY:
+ /* Rewrite reads from XYZW to XXXX. */
+ for (i = 0; i < 4; i++)
+ if (swiz[i] <= SWIZZLE_W)
+ swiz[i] = SWIZZLE_X;
+ break;
+
+ case GL_ALPHA:
+ /* Rewrite reads from W to X, and reads from XYZ to 000. */
+ for (i = 0; i < 4; i++)
+ if (swiz[i] == SWIZZLE_W)
+ swiz[i] = SWIZZLE_X;
+ else if (swiz[i] < SWIZZLE_W)
+ swiz[i] = SWIZZLE_ZERO;
+ break;
+ case GL_RED:
+ /* Rewrite reads W to 1, XYZ to X00 */
+ for (i = 0; i < 4; i++)
+ if (swiz[i] == SWIZZLE_W)
+ swiz[i] = SWIZZLE_ONE;
+ else if (swiz[i] == SWIZZLE_Y || swiz[i] == SWIZZLE_Z)
+ swiz[i] = SWIZZLE_ZERO;
+ break;
+ }
+
+ return MAKE_SWIZZLE4(swiz[0], swiz[1], swiz[2], swiz[3]);
+}
+
+
+/**
+ * Return TRUE if the swizzling described by "swizzle" and
+ * "depthmode" (for depth textures only) is different from the swizzling
+ * set in the given sampler view.
+ *
+ * \param sv A sampler view.
+ * \param swizzle Texture swizzle, a bitmask computed using MAKE_SWIZZLE4.
+ * \param depthmode One of GL_LUMINANCE, GL_INTENSITY, GL_ALPHA.
+ */
+static boolean
+check_sampler_swizzle(struct pipe_sampler_view *sv,
+ GLuint swizzle, GLenum depthmode)