demos/teapot: Add a tessellation demo.

Approved-by: Henri Verbeet (@hverbeet) Merge-Request: https://gitlab.winehq.org/wine/vkd3d/-/merge_requests/1575
2025-09-12 18:50:22 -07:00 · 2025-06-16 18:49:08 +02:00 · 2025-06-18 16:00:25 +02:00
parent d572f4ac1f
commit 5911e410a8
8 changed files with 932 additions and 24 deletions
--- a/Makefile.am
+++ b/Makefile.am
@@ -325,6 +325,7 @@ vkd3d_test_headers = \

 vkd3d_demos = \
 	demos/vkd3d-gears \
+	demos/vkd3d-teapot \
 	demos/vkd3d-triangle

 vkd3d_demos_headers = \
@@ -549,6 +550,14 @@ demos_vkd3d_gears_CFLAGS = $(DEMOS_CFLAGS)
 demos_vkd3d_gears_LDADD = $(DEMOS_LDADD) -lm
 demos/vkd3d_gears-gears.$(OBJEXT): demos/gears.hlsl

+demos_vkd3d_teapot_SOURCES = \
+	demos/teapot.c \
+	demos/teapot.h \
+	demos/teapot.hlsl
+demos_vkd3d_teapot_CFLAGS = $(DEMOS_CFLAGS)
+demos_vkd3d_teapot_LDADD = $(DEMOS_LDADD) -lm
+demos/vkd3d_teapot-teapot.$(OBJEXT): demos/teapot.hlsl
+
 demos_vkd3d_triangle_SOURCES = demos/triangle.c demos/triangle.hlsl
 demos_vkd3d_triangle_CFLAGS = $(DEMOS_CFLAGS)
 demos_vkd3d_triangle_LDADD = $(DEMOS_LDADD)
@@ -657,6 +666,7 @@ endif
 if BUILD_DEMOS
 CROSS32_EXEFILES += $(vkd3d_demos:demos/vkd3d-%=demos/%.cross32.exe)
 demos/gears.cross32.exe: demos/gears.hlsl
+demos/teapot.cross32.exe: demos/teapot.hlsl
 demos/triangle.cross32.exe: demos/triangle.hlsl
 endif

@@ -706,6 +716,7 @@ endif
 if BUILD_DEMOS
 CROSS64_EXEFILES += $(vkd3d_demos:demos/vkd3d-%=demos/%.cross64.exe)
 demos/gears.cross64.exe: demos/gears.hlsl
+demos/teapot.cross64.exe: demos/teapot.hlsl
 demos/triangle.cross64.exe: demos/triangle.hlsl
 endif

--- a/demos/demo.h
+++ b/demos/demo.h
@@ -38,6 +38,7 @@
 #define COBJMACROS
 #include <vkd3d_d3d12.h>
 #include <inttypes.h>
+#include <math.h>

 #ifdef __WIN32__
 #define DEMO_ASM_PUSHSECTION ".section rdata\n\t"
@@ -81,12 +82,14 @@

 #define ARRAY_SIZE(x) (sizeof(x) / sizeof(*x))

-#define DEMO_KEY_UNKNOWN    0x0000
-#define DEMO_KEY_ESCAPE     0xff1b
-#define DEMO_KEY_LEFT       0xff51
-#define DEMO_KEY_UP         0xff52
-#define DEMO_KEY_RIGHT      0xff53
-#define DEMO_KEY_DOWN       0xff54
+#define DEMO_KEY_UNKNOWN        0x0000
+#define DEMO_KEY_ESCAPE         0xff1b
+#define DEMO_KEY_LEFT           0xff51
+#define DEMO_KEY_UP             0xff52
+#define DEMO_KEY_RIGHT          0xff53
+#define DEMO_KEY_DOWN           0xff54
+#define DEMO_KEY_KP_ADD         0xffab
+#define DEMO_KEY_KP_SUBTRACT    0xffad

 struct demo_vec3
 {
@@ -103,6 +106,11 @@ struct demo_matrix
    float m[4][4];
 };

+struct demo_patch
+{
+    uint16_t p[4][4];
+};
+
 struct demo_swapchain_desc
 {
    unsigned int width;
@@ -120,6 +128,36 @@ static inline void demo_vec3_set(struct demo_vec3 *v, float x, float y, float z)
    v->z = z;
 }

+static inline void demo_vec3_subtract(struct demo_vec3 *v, const struct demo_vec3 *a, const struct demo_vec3 *b)
+{
+    demo_vec3_set(v, a->x - b->x, a->y - b->y, a->z - b->z);
+}
+
+static inline float demo_vec3_dot(const struct demo_vec3 *a, const struct demo_vec3 *b)
+{
+    return a->x * b->x + a->y * b->y + a->z * b->z;
+}
+
+static inline float demo_vec3_length(const struct demo_vec3 *v)
+{
+    return sqrtf(demo_vec3_dot(v, v));
+}
+
+static inline void demo_vec3_scale(struct demo_vec3 *v, const struct demo_vec3 *a, float s)
+{
+    demo_vec3_set(v, a->x * s, a->y * s, a->z *s);
+}
+
+static inline void demo_vec3_normalise(struct demo_vec3 *v, const struct demo_vec3 *a)
+{
+    demo_vec3_scale(v, a, 1.0f / demo_vec3_length(a));
+}
+
+static inline void demo_vec3_cross(struct demo_vec3 *v, const struct demo_vec3 *a, const struct demo_vec3 *b)
+{
+    demo_vec3_set(v, a->y * b->z - a->z * b->y, a->z * b->x - a->x * b->z, a->x * b->y - a->y * b->x);
+}
+
 static inline void demo_vec4_set(struct demo_vec4 *v, float x, float y, float z, float w)
 {
    v->x = x;
@@ -128,6 +166,27 @@ static inline void demo_vec4_set(struct demo_vec4 *v, float x, float y, float z,
    v->w = w;
 }

+static inline void demo_matrix_look_at_rh(struct demo_matrix *m, const struct demo_vec3 *eye,
+        const struct demo_vec3 *ref, const struct demo_vec3 *up)
+{
+    struct demo_vec3 f, s, t, u;
+
+    demo_vec3_subtract(&f, eye, ref);
+    demo_vec3_normalise(&f, &f);
+    demo_vec3_cross(&s, up, &f);
+    demo_vec3_normalise(&s, &s);
+    demo_vec3_cross(&u, &f, &s);
+    demo_vec3_set(&t, demo_vec3_dot(&s, eye), demo_vec3_dot(&u, eye), demo_vec3_dot(&f, eye));
+
+    *m = (struct demo_matrix)
+    {{
+        { s.x,  u.x,  f.x, 0.0f},
+        { s.y,  u.y,  f.y, 0.0f},
+        { s.z,  u.z,  f.z, 0.0f},
+        {-t.x, -t.y, -t.z, 1.0f},
+    }};
+}
+
 static inline void demo_matrix_multiply(struct demo_matrix *out,
        const struct demo_matrix *a, const struct demo_matrix *b)
 {
--- a/demos/demo_macos.h
+++ b/demos/demo_macos.h
@@ -176,12 +176,16 @@ static demo_key demo_key_from_nsevent(id event)
 {
    enum vkey
    {
-        kVK_ANSI_A      = 0x00,
-        kVK_Escape      = 0x35,
-        kVK_LeftArrow   = 0x7b,
-        kVK_RightArrow  = 0x7c,
-        kVK_DownArrow   = 0x7d,
-        kVK_UpArrow     = 0x7e,
+        kVK_ANSI_A              = 0x00,
+        kVK_ANSI_Equal          = 0x18,
+        kVK_ANSI_Minus          = 0x1b,
+        kVK_Escape              = 0x35,
+        kVK_ANSI_KeypadPlus     = 0x45,
+        kVK_ANSI_KeypadMinus    = 0x4e,
+        kVK_LeftArrow           = 0x7b,
+        kVK_RightArrow          = 0x7c,
+        kVK_DownArrow           = 0x7d,
+        kVK_UpArrow             = 0x7e,
    } vkey;
    size_t i;

@@ -192,12 +196,16 @@ static demo_key demo_key_from_nsevent(id event)
    }
    lookup[] =
    {
-        {kVK_ANSI_A,        'a'},
-        {kVK_Escape,        DEMO_KEY_ESCAPE},
-        {kVK_LeftArrow,     DEMO_KEY_LEFT},
-        {kVK_RightArrow,    DEMO_KEY_RIGHT},
-        {kVK_UpArrow,       DEMO_KEY_UP},
-        {kVK_DownArrow,     DEMO_KEY_DOWN},
+        {kVK_ANSI_A,            'a'},
+        {kVK_ANSI_Equal,        '='},
+        {kVK_ANSI_Minus,        '-'},
+        {kVK_Escape,            DEMO_KEY_ESCAPE},
+        {kVK_ANSI_KeypadPlus,   DEMO_KEY_KP_ADD},
+        {kVK_ANSI_KeypadMinus,  DEMO_KEY_KP_SUBTRACT},
+        {kVK_LeftArrow,         DEMO_KEY_LEFT},
+        {kVK_RightArrow,        DEMO_KEY_RIGHT},
+        {kVK_DownArrow,         DEMO_KEY_DOWN},
+        {kVK_UpArrow,           DEMO_KEY_UP},
    };

    vkey = NSEvent_keyCode(event);
--- a/demos/demo_win32.h
+++ b/demos/demo_win32.h
@@ -127,11 +127,15 @@ static demo_key demo_key_from_win32_vkey(DWORD vkey)
    }
    lookup[] =
    {
-        {VK_ESCAPE, DEMO_KEY_ESCAPE},
-        {VK_LEFT,   DEMO_KEY_LEFT},
-        {VK_RIGHT,  DEMO_KEY_RIGHT},
-        {VK_UP,     DEMO_KEY_UP},
-        {VK_DOWN,   DEMO_KEY_DOWN},
+        {VK_OEM_MINUS,  '-'},
+        {VK_OEM_PLUS,   '='},
+        {VK_ESCAPE,     DEMO_KEY_ESCAPE},
+        {VK_LEFT,       DEMO_KEY_LEFT},
+        {VK_UP,         DEMO_KEY_UP},
+        {VK_RIGHT,      DEMO_KEY_RIGHT},
+        {VK_DOWN,       DEMO_KEY_DOWN},
+        {VK_ADD,        DEMO_KEY_KP_ADD},
+        {VK_SUBTRACT,   DEMO_KEY_KP_SUBTRACT},
    };
    unsigned int i;

--- a/demos/gears.c
+++ b/demos/gears.c
@@ -45,7 +45,6 @@
 #include <sys/time.h>
 #include <assert.h>
 #include <stdio.h>
-#include <math.h>
 #include "demo.h"

 DEMO_EMBED(gears_hlsl, "gears.hlsl");
--- a/demos/teapot.c
+++ b/demos/teapot.c
--- a/demos/teapot.h
+++ b/demos/teapot.h
@@ -0,0 +1,129 @@
+/*
+ * Copyright 2025 Henri Verbeet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+/* Teapot data adapted from freeglut's fg_teapot_data.h with the following license:
+ *
+ *     Permission is hereby granted, free of charge, to any person obtaining a
+ *     copy of this software and associated documentation files (the "Software"),
+ *     to deal in the Software without restriction, including without limitation
+ *     the rights to use, copy, modify, merge, publish, distribute, sublicense,
+ *     and/or sell copies of the Software, and to permit persons to whom the
+ *     Software is furnished to do so, subject to the following conditions:
+ *
+ *     The above copyright notice and this permission notice shall be included
+ *     in all copies or substantial portions of the Software.
+ *
+ *     THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS
+ *     OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ *     FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT.  IN NO EVENT SHALL
+ *     PAWEL W. OLSZTA BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER
+ *     IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN
+ *     CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.
+ *
+ * The data is of course ultimately derived from Martin Newell's famous
+ * teapot, also known as the Utah teapot.
+ */
+
+/* Rim, body, lid, and bottom data must be rotated along all four quadrants;
+ * handle and spout data is flipped (negate y values) only. */
+
+static const struct demo_patch teapot_rotate_patches[] =
+{
+    {{{  0,   1,   2,   3}, {  4,   5,   6,   7}, {  8,   9,  10,  11}, { 12,  13,  14,  15}}}, /* rim    */
+    {{{ 12,  13,  14,  15}, { 16,  17,  18,  19}, { 20,  21,  22,  23}, { 24,  25,  26,  27}}}, /* body   */
+    {{{ 24,  25,  26,  27}, { 28,  29,  30,  31}, { 32,  33,  34,  35}, { 36,  37,  38,  39}}},
+    {{{ 40,  40,  40,  40}, { 43,  44,  45,  46}, { 47,  47,  47,  47}, { 48,  49,  50,  51}}}, /* lid    */
+    {{{ 48,  49,  50,  51}, { 52,  53,  54,  55}, { 56,  57,  58,  59}, { 60,  61,  62,  63}}},
+    {{{ 64,  64,  64,  64}, { 65,  66,  67,  68}, { 69,  70,  71,  72}, { 39,  38,  37,  36}}}, /* bottom */
+},
+teapot_flip_patches[] =
+{
+    {{{ 73,  74,  75,  76}, { 77,  78,  79,  80}, { 81,  82,  83,  84}, { 85,  86,  87,  88}}}, /* handle */
+    {{{ 85,  86,  87,  88}, { 89,  90,  91,  92}, { 93,  94,  95,  96}, { 97,  98,  99, 100}}},
+    {{{101, 102, 103, 104}, {105, 106, 107, 108}, {109, 110, 111, 112}, {113, 114, 115, 116}}}, /* spout  */
+    {{{113, 114, 115, 116}, {117, 118, 119, 120}, {121, 122, 123, 124}, {125, 126, 127, 128}}},
+};
+
+static const struct demo_vec3 teapot_control_points[] =
+{
+    { 1.40000f,  0.00000f,  2.40000f}, { 1.40000f, -0.78400f,  2.40000f},
+    { 0.78400f, -1.40000f,  2.40000f}, { 0.00000f, -1.40000f,  2.40000f},
+    { 1.33750f,  0.00000f,  2.53125f}, { 1.33750f, -0.74900f,  2.53125f},
+    { 0.74900f, -1.33750f,  2.53125f}, { 0.00000f, -1.33750f,  2.53125f},
+    { 1.43750f,  0.00000f,  2.53125f}, { 1.43750f, -0.80500f,  2.53125f},
+    { 0.80500f, -1.43750f,  2.53125f}, { 0.00000f, -1.43750f,  2.53125f},
+    { 1.50000f,  0.00000f,  2.40000f}, { 1.50000f, -0.84000f,  2.40000f},
+    { 0.84000f, -1.50000f,  2.40000f}, { 0.00000f, -1.50000f,  2.40000f},
+    { 1.75000f,  0.00000f,  1.87500f}, { 1.75000f, -0.98000f,  1.87500f},
+    { 0.98000f, -1.75000f,  1.87500f}, { 0.00000f, -1.75000f,  1.87500f},
+    { 2.00000f,  0.00000f,  1.35000f}, { 2.00000f, -1.12000f,  1.35000f},
+    { 1.12000f, -2.00000f,  1.35000f}, { 0.00000f, -2.00000f,  1.35000f},
+    { 2.00000f,  0.00000f,  0.90000f}, { 2.00000f, -1.12000f,  0.90000f},
+    { 1.12000f, -2.00000f,  0.90000f}, { 0.00000f, -2.00000f,  0.90000f},
+    { 2.00000f,  0.00000f,  0.45000f}, { 2.00000f, -1.12000f,  0.45000f},
+    { 1.12000f, -2.00000f,  0.45000f}, { 0.00000f, -2.00000f,  0.45000f},
+    { 1.50000f,  0.00000f,  0.22500f}, { 1.50000f, -0.84000f,  0.22500f},
+    { 0.84000f, -1.50000f,  0.22500f}, { 0.00000f, -1.50000f,  0.22500f},
+    { 1.50000f,  0.00000f,  0.15000f}, { 1.50000f, -0.84000f,  0.15000f},
+    { 0.84000f, -1.50000f,  0.15000f}, { 0.00000f, -1.50000f,  0.15000f},
+    { 0.00000f,  0.00000f,  3.15000f}, { 0.00000f, -0.00200f,  3.15000f},
+    { 0.00200f,  0.00000f,  3.15000f}, { 0.80000f,  0.00000f,  3.15000f},
+    { 0.80000f, -0.45000f,  3.15000f}, { 0.45000f, -0.80000f,  3.15000f},
+    { 0.00000f, -0.80000f,  3.15000f}, { 0.00000f,  0.00000f,  2.85000f},
+    { 0.20000f,  0.00000f,  2.70000f}, { 0.20000f, -0.11200f,  2.70000f},
+    { 0.11200f, -0.20000f,  2.70000f}, { 0.00000f, -0.20000f,  2.70000f},
+    { 0.40000f,  0.00000f,  2.55000f}, { 0.40000f, -0.22400f,  2.55000f},
+    { 0.22400f, -0.40000f,  2.55000f}, { 0.00000f, -0.40000f,  2.55000f},
+    { 1.30000f,  0.00000f,  2.55000f}, { 1.30000f, -0.72800f,  2.55000f},
+    { 0.72800f, -1.30000f,  2.55000f}, { 0.00000f, -1.30000f,  2.55000f},
+    { 1.30000f,  0.00000f,  2.40000f}, { 1.30000f, -0.72800f,  2.40000f},
+    { 0.72800f, -1.30000f,  2.40000f}, { 0.00000f, -1.30000f,  2.40000f},
+    { 0.00000f,  0.00000f,  0.00000f}, { 0.00000f, -1.42500f,  0.00000f},
+    { 0.79800f, -1.42500f,  0.00000f}, { 1.42500f, -0.79800f,  0.00000f},
+    { 1.42500f,  0.00000f,  0.00000f}, { 0.00000f, -1.50000f,  0.07500f},
+    { 0.84000f, -1.50000f,  0.07500f}, { 1.50000f, -0.84000f,  0.07500f},
+    { 1.50000f,  0.00000f,  0.07500f}, {-1.60000f,  0.00000f,  2.02500f},
+    {-1.60000f, -0.30000f,  2.02500f}, {-1.50000f, -0.30000f,  2.25000f},
+    {-1.50000f,  0.00000f,  2.25000f}, {-2.30000f,  0.00000f,  2.02500f},
+    {-2.30000f, -0.30000f,  2.02500f}, {-2.50000f, -0.30000f,  2.25000f},
+    {-2.50000f,  0.00000f,  2.25000f}, {-2.70000f,  0.00000f,  2.02500f},
+    {-2.70000f, -0.30000f,  2.02500f}, {-3.00000f, -0.30000f,  2.25000f},
+    {-3.00000f,  0.00000f,  2.25000f}, {-2.70000f,  0.00000f,  1.80000f},
+    {-2.70000f, -0.30000f,  1.80000f}, {-3.00000f, -0.30000f,  1.80000f},
+    {-3.00000f,  0.00000f,  1.80000f}, {-2.70000f,  0.00000f,  1.57500f},
+    {-2.70000f, -0.30000f,  1.57500f}, {-3.00000f, -0.30000f,  1.35000f},
+    {-3.00000f,  0.00000f,  1.35000f}, {-2.50000f,  0.00000f,  1.12500f},
+    {-2.50000f, -0.30000f,  1.12500f}, {-2.65000f, -0.30000f,  0.93750f},
+    {-2.65000f,  0.00000f,  0.93750f}, {-2.00000f,  0.00000f,  0.90000f},
+    {-2.00000f, -0.30000f,  0.90000f}, {-1.90000f, -0.30000f,  0.60000f},
+    {-1.90000f,  0.00000f,  0.60000f}, { 1.70000f,  0.00000f,  1.42500f},
+    { 1.70000f, -0.66000f,  1.42500f}, { 1.70000f, -0.66000f,  0.60000f},
+    { 1.70000f,  0.00000f,  0.60000f}, { 2.60000f,  0.00000f,  1.42500f},
+    { 2.60000f, -0.66000f,  1.42500f}, { 3.10000f, -0.66000f,  0.82500f},
+    { 3.10000f,  0.00000f,  0.82500f}, { 2.30000f,  0.00000f,  2.10000f},
+    { 2.30000f, -0.25000f,  2.10000f}, { 2.40000f, -0.25000f,  2.02500f},
+    { 2.40000f,  0.00000f,  2.02500f}, { 2.70000f,  0.00000f,  2.40000f},
+    { 2.70000f, -0.25000f,  2.40000f}, { 3.30000f, -0.25000f,  2.40000f},
+    { 3.30000f,  0.00000f,  2.40000f}, { 2.80000f,  0.00000f,  2.47500f},
+    { 2.80000f, -0.25000f,  2.47500f}, { 3.52500f, -0.25000f,  2.49375f},
+    { 3.52500f,  0.00000f,  2.49375f}, { 2.90000f,  0.00000f,  2.47500f},
+    { 2.90000f, -0.15000f,  2.47500f}, { 3.45000f, -0.15000f,  2.51250f},
+    { 3.45000f,  0.00000f,  2.51250f}, { 2.80000f,  0.00000f,  2.40000f},
+    { 2.80000f, -0.15000f,  2.40000f}, { 3.20000f, -0.15000f,  2.40000f},
+    { 3.20000f,  0.00000f,  2.40000f}
+};
--- a/demos/teapot.hlsl
+++ b/demos/teapot.hlsl
@@ -0,0 +1,121 @@
+/*
+ * Copyright 2025 Henri Verbeet
+ *
+ * This library is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU Lesser General Public
+ * License as published by the Free Software Foundation; either
+ * version 2.1 of the License, or (at your option) any later version.
+ *
+ * This library is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
+ * Lesser General Public License for more details.
+ *
+ * You should have received a copy of the GNU Lesser General Public
+ * License along with this library; if not, write to the Free Software
+ * Foundation, Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301, USA
+ */
+
+cbuffer teapot_cb : register(b0)
+{
+    float4x4 mvp_matrix;
+    float level;
+};
+
+struct control_point
+{
+    float4 position : SV_POSITION;
+};
+
+struct patch_constant_data
+{
+    float edges[4] : SV_TessFactor;
+    float inside[2] : SV_InsideTessFactor;
+};
+
+struct ps_in
+{
+    float4 position : SV_POSITION;
+};
+
+float4 vs_main(float4 position : POSITION, uint id : SV_InstanceID) : SV_POSITION
+{
+    /* Mirror/flip patches based on the instance ID. */
+    position.w = -1.0;
+    if (id & 1)
+        position.yw = -position.yw;
+    if (id & 2)
+        position.xw = -position.xw;
+
+    return position;
+}
+
+struct patch_constant_data patch_constant(InputPatch<control_point, 16> input)
+{
+    struct patch_constant_data output;
+
+    output.edges[0] = level;
+    output.edges[1] = level;
+    output.edges[2] = level;
+    output.edges[3] = level;
+    output.inside[0] = level;
+    output.inside[1] = level;
+
+    return output;
+}
+
+[domain("quad")]
+[outputcontrolpoints(16)]
+[outputtopology("triangle_ccw")]
+[partitioning("integer")]
+[patchconstantfunc("patch_constant")]
+struct control_point hs_main(InputPatch<control_point, 16> input, uint i : SV_OutputControlPointID)
+{
+    /* Reorder mirrored/flipped control points. */
+    if (input[0].position.w < 0.0)
+    {
+        uint u = i % 4, v = i / 4;
+        return input[v * 4 + (3 - u)];
+    }
+
+    return input[i];
+}
+
+float3 eval_quadratic(float3 p0, float3 p1, float3 p2, float t)
+{
+    return lerp(lerp(p0, p1, t), lerp(p1, p2, t), t);
+}
+
+float3 eval_cubic(float3 p0, float3 p1, float3 p2, float3 p3, float t)
+{
+    return lerp(eval_quadratic(p0, p1, p2, t),
+            eval_quadratic(p1, p2, p3, t), t);
+}
+
+struct ps_in eval_patch(float2 t, float4 p[16])
+{
+    float3 position, q[4];
+    struct ps_in o;
+
+    q[0] = eval_cubic(p[0].xyz, p[4].xyz,  p[8].xyz, p[12].xyz, t.y);
+    q[1] = eval_cubic(p[1].xyz, p[5].xyz,  p[9].xyz, p[13].xyz, t.y);
+    q[2] = eval_cubic(p[2].xyz, p[6].xyz, p[10].xyz, p[14].xyz, t.y);
+    q[3] = eval_cubic(p[3].xyz, p[7].xyz, p[11].xyz, p[15].xyz, t.y);
+
+    position = eval_cubic(q[0], q[1], q[2], q[3], t.x);
+    o.position = mul(mvp_matrix, float4(position, 1.0));
+
+    return o;
+}
+
+[domain("quad")]
+struct ps_in ds_main(struct patch_constant_data input,
+        float2 tess_coord : SV_DomainLocation, const OutputPatch<control_point, 16> patch)
+{
+    return eval_patch(tess_coord, patch);
+}
+
+float4 ps_main(struct ps_in i) : SV_TARGET
+{
+    return float4(1.0, 0.69, 0.0, 1.0);
+}