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-rw-r--r--src/mesa/swrast/s_depth.c41
1 files changed, 27 insertions, 14 deletions
diff --git a/src/mesa/swrast/s_depth.c b/src/mesa/swrast/s_depth.c
index 0b6bb7e3ec9..ac5dae2148b 100644
--- a/src/mesa/swrast/s_depth.c
+++ b/src/mesa/swrast/s_depth.c
@@ -497,17 +497,24 @@ depth_test_span32( GLcontext *ctx, GLuint n,
return passed;
}
-/* Apply ARB_depth_clamp to span of fragments. */
+
+
+/**
+ * Clamp fragment Z values to the depth near/far range (glDepthRange()).
+ * This is used when GL_ARB_depth_clamp/GL_DEPTH_CLAMP is turned on.
+ * In that case, vertexes are not clipped against the near/far planes
+ * so rasterization will produce fragment Z values outside the usual
+ * [0,1] range.
+ */
void
_swrast_depth_clamp_span( GLcontext *ctx, SWspan *span )
{
struct gl_framebuffer *fb = ctx->DrawBuffer;
- struct gl_renderbuffer *rb = fb->_DepthBuffer;
const GLuint count = span->end;
- GLuint *zValues = span->array->z;
- GLuint min, max;
+ GLint *zValues = (GLint *) span->array->z; /* sign change */
+ GLint min, max;
GLfloat min_f, max_f;
- int i;
+ GLuint i;
if (ctx->Viewport.Near < ctx->Viewport.Far) {
min_f = ctx->Viewport.Near;
@@ -517,15 +524,21 @@ _swrast_depth_clamp_span( GLcontext *ctx, SWspan *span )
max_f = ctx->Viewport.Near;
}
- if (rb->DataType == GL_UNSIGNED_SHORT) {
- CLAMPED_FLOAT_TO_USHORT(min, min_f);
- CLAMPED_FLOAT_TO_USHORT(max, max_f);
- } else {
- assert(rb->DataType == GL_UNSIGNED_INT);
- min = FLOAT_TO_UINT(min_f);
- max = FLOAT_TO_UINT(max_f);
- }
-
+ /* Convert floating point values in [0,1] to device Z coordinates in
+ * [0, DepthMax].
+ * ex: If the the Z buffer has 24 bits, DepthMax = 0xffffff.
+ *
+ * XXX this all falls apart if we have 31 or more bits of Z because
+ * the triangle rasterization code produces unsigned Z values. Negative
+ * vertex Z values come out as large fragment Z uints.
+ */
+ min = (GLint) (min_f * fb->_DepthMaxF);
+ max = (GLint) (max_f * fb->_DepthMaxF);
+ if (max < 0)
+ max = 0x7fffffff; /* catch over flow for 30-bit z */
+
+ /* Note that we do the comparisons here using signed integers.
+ */
for (i = 0; i < count; i++) {
if (zValues[i] < min)
zValues[i] = min;