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-rw-r--r--src/mesa/main/image.c31
1 files changed, 31 insertions, 0 deletions
diff --git a/src/mesa/main/image.c b/src/mesa/main/image.c
index 394a7c65cdf..dcd7f10b26e 100644
--- a/src/mesa/main/image.c
+++ b/src/mesa/main/image.c
@@ -3893,6 +3893,36 @@ _mesa_unpack_depth_span( const GLcontext *ctx, GLuint n,
{
GLfloat depthTemp[MAX_WIDTH], *depthValues;
+ /* Look for special cases first.
+ * Not only are these faster, they're less prone to numeric conversion
+ * problems. Otherwise, converting from an int type to a float then
+ * back to an int type can introduce errors that will show up as
+ * artifacts in things like depth peeling which uses glCopyTexImage.
+ */
+ if (ctx->Pixel.DepthScale == 1.0 && ctx->Pixel.DepthBias == 0.0) {
+ if (srcType == GL_UNSIGNED_INT && dstType == GL_UNSIGNED_SHORT) {
+ const GLuint *src = (const GLuint *) source;
+ GLushort *dst = (GLushort *) dest;
+ GLuint i;
+ for (i = 0; i < n; i++) {
+ dst[i] = src[i] >> 16;
+ }
+ return;
+ }
+ if (srcType == GL_UNSIGNED_SHORT && dstType == GL_UNSIGNED_INT) {
+ const GLushort *src = (const GLushort *) source;
+ GLuint *dst = (GLuint *) dest;
+ GLuint i;
+ for (i = 0; i < n; i++) {
+ dst[i] = src[i] | (src[i] << 16);
+ }
+ return;
+ }
+ /* XXX may want to add additional cases here someday */
+ }
+
+ /* general case path */
+
if (dstType == GL_FLOAT) {
depthValues = (GLfloat *) dest;
}
@@ -3903,6 +3933,7 @@ _mesa_unpack_depth_span( const GLcontext *ctx, GLuint n,
/* XXX we need to obey srcPacking->SwapBytes here!!! */
(void) srcPacking;
+ /* convert incoming values to GLfloat */
switch (srcType) {
case GL_BYTE:
DEPTH_VALUES(GLbyte, BYTE_TO_FLOAT);