+extern void GLAPIENTRY
+_mesa_ClipControl(GLenum origin, GLenum depth)
+{
+ GET_CURRENT_CONTEXT(ctx);
+
+ if (MESA_VERBOSE&VERBOSE_API)
+ _mesa_debug(ctx, "glClipControl(%s, %s)\n",
+ _mesa_lookup_enum_by_nr(origin),
+ _mesa_lookup_enum_by_nr(depth));
+
+ ASSERT_OUTSIDE_BEGIN_END(ctx);
+
+ if (!ctx->Extensions.ARB_clip_control) {
+ _mesa_error(ctx, GL_INVALID_OPERATION, "glClipControl");
+ return;
+ }
+
+ if (origin != GL_LOWER_LEFT && origin != GL_UPPER_LEFT) {
+ _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
+ return;
+ }
+
+ if (depth != GL_NEGATIVE_ONE_TO_ONE && depth != GL_ZERO_TO_ONE) {
+ _mesa_error(ctx, GL_INVALID_ENUM, "glClipControl");
+ return;
+ }
+
+ if (ctx->Transform.ClipOrigin == origin &&
+ ctx->Transform.ClipDepthMode == depth)
+ return;
+
+ /* Affects transform state and the viewport transform */
+ FLUSH_VERTICES(ctx, _NEW_TRANSFORM | _NEW_VIEWPORT);
+
+ if (ctx->Transform.ClipOrigin != origin) {
+ ctx->Transform.ClipOrigin = origin;
+
+ /* Affects the winding order of the front face. */
+ ctx->NewState |= _NEW_POLYGON;
+
+ if (ctx->Driver.FrontFace)
+ ctx->Driver.FrontFace(ctx, ctx->Polygon.FrontFace);
+ }
+
+ if (ctx->Transform.ClipDepthMode != depth) {
+ ctx->Transform.ClipDepthMode = depth;
+
+ if (ctx->Driver.DepthRange)
+ ctx->Driver.DepthRange(ctx);
+ }
+}
+
+/**
+ * Computes the scaling and the translation part of the
+ * viewport transform matrix of the \param i-th viewport
+ * and writes that into \param scale and \param translate.
+ */
+void
+_mesa_get_viewport_xform(struct gl_context *ctx, unsigned i,
+ double scale[3], double translate[3])
+{
+ double x = ctx->ViewportArray[i].X;
+ double y = ctx->ViewportArray[i].Y;
+ double half_width = 0.5*ctx->ViewportArray[i].Width;
+ double half_height = 0.5*ctx->ViewportArray[i].Height;
+ double n = ctx->ViewportArray[i].Near;
+ double f = ctx->ViewportArray[i].Far;
+
+ scale[0] = half_width;
+ translate[0] = half_width + x;
+ if (ctx->Transform.ClipOrigin == GL_UPPER_LEFT) {
+ scale[1] = -half_height;
+ translate[1] = half_height - y;
+ } else {
+ scale[1] = half_height;
+ translate[1] = half_height + y;
+ }
+ if (ctx->Transform.ClipDepthMode == GL_NEGATIVE_ONE_TO_ONE) {
+ scale[2] = 0.5*(f - n);
+ translate[2] = 0.5*(n + f);
+ } else {
+ scale[2] = f - n;
+ translate[2] = n;
+ }
+}