1 <!DOCTYPE HTML PUBLIC
"-//W3C//DTD HTML 4.01 Transitional//EN" "http://www.w3.org/TR/html4/loose.dtd">
4 <meta http-equiv=
"content-type" content=
"text/html; charset=utf-8">
5 <title>Viewperf Issues
</title>
6 <link rel=
"stylesheet" type=
"text/css" href=
"mesa.css">
10 <h1>Viewperf Issues
</h1>
13 This page lists known issues with
14 <a href=
"http://www.spec.org/gwpg/gpc.static/vp11info.html" target=
"_main">SPEC Viewperf
11</a>
15 when running on Mesa-based drivers.
19 The Viewperf data sets are basically GL API traces that are recorded from
20 CAD applications, then replayed in the Viewperf framework.
24 The primary problem with these traces is they blindly use features and
25 OpenGL extensions that were supported by the OpenGL driver when the trace
27 but there's no checks to see if those features are supported by the driver
28 when playing back the traces with Viewperf.
32 These issues have been reported to the SPEC organization in the hope that
33 they'll be fixed in the future.
37 Some of the Viewperf tests use a lot of memory.
38 At least
2GB of RAM is recommended.
42 <h2>Catia-
03 test
2</h2>
45 This test creates over
38000 vertex buffer objects. On some systems
46 this can exceed the maximum number of buffer allocations. Mesa
47 generates GL_OUT_OF_MEMORY errors in this situation, but Viewperf
48 does no error checking and continues. When this happens, some drawing
49 commands become no-ops. This can also eventually lead to a segfault
50 either in Viewperf or the Mesa driver.
55 <h2>Catia-
03 tests
3,
4,
8</h2>
58 These tests use features of the
59 <a href=
"http://www.opengl.org/registry/specs/NV/fragment_program2.txt"
61 GL_NV_fragment_program2
</a> and
62 <a href=
"http://www.opengl.org/registry/specs/NV/vertex_program3.txt"
64 GL_NV_vertex_program3
</a> extensions without checking if the driver supports
68 When Mesa tries to compile the vertex/fragment programs it generates errors
69 (which Viewperf ignores).
70 Subsequent drawing calls become no-ops and the rendering is incorrect.
75 <h2>sw-
02 tests
1,
2,
4,
6</h2>
78 These tests depend on the
79 <a href=
"http://www.opengl.org/registry/specs/NV/primitive_restart.txt"
80 target=
"_main">GL_NV_primitive_restart
</a> extension.
84 If the Mesa driver doesn't support this extension the rendering will
85 be incorrect and the test will fail.
89 Also, the color of the line drawings in test
2 seem to appear in a random
90 color. This is probably due to some uninitialized state somewhere.
98 The lines drawn in this test appear in a random color.
99 That's because texture mapping is enabled when the lines are drawn, but no
100 texture image is defined (glTexImage2D() is called with pixels=NULL).
101 Since GL says the contents of the texture image are undefined in that
102 situation, we get a random color.
107 <h2>Lightwave-
01 test
3</h2>
110 This test uses a number of mipmapped textures, but the textures are
111 incomplete because the last/smallest mipmap level (
1 x
1 pixel) is
116 A trace captured with
117 <a href=
"https://github.com/apitrace/apitrace" target=
"_main">API trace
</a>
118 shows this sequences of calls like this:
121 2504 glBindTexture(target = GL_TEXTURE_2D, texture =
55)
122 2505 glTexImage2D(target = GL_TEXTURE_2D, level =
0, internalformat = GL_RGBA, width =
512, height =
512, border =
0, format = GL_RGB, type = GL_UNSIGNED_SHORT, pixels = blob(
1572864))
123 2506 glTexImage2D(target = GL_TEXTURE_2D, level =
1, internalformat = GL_RGBA, width =
256, height =
256, border =
0, format = GL_RGB, type = GL_UNSIGNED_SHORT, pixels = blob(
393216))
124 2507 glTexImage2D(target = GL_TEXTURE_2D, level =
2, internalformat = GL_RGBA, width =
128, height =
128, border =
0, format = GL_RGB, type = GL_UNSIGNED_SHORT, pixels = blob(
98304))
126 2512 glTexImage2D(target = GL_TEXTURE_2D, level =
7, internalformat = GL_RGBA, width =
4, height =
4, border =
0, format = GL_RGB, type = GL_UNSIGNED_SHORT, pixels = blob(
96))
127 2513 glTexImage2D(target = GL_TEXTURE_2D, level =
8, internalformat = GL_RGBA, width =
2, height =
2, border =
0, format = GL_RGB, type = GL_UNSIGNED_SHORT, pixels = blob(
24))
128 2514 glTexParameteri(target = GL_TEXTURE_2D, pname = GL_TEXTURE_MIN_FILTER, param = GL_LINEAR_MIPMAP_LINEAR)
129 2515 glTexParameteri(target = GL_TEXTURE_2D, pname = GL_TEXTURE_WRAP_S, param = GL_REPEAT)
130 2516 glTexParameteri(target = GL_TEXTURE_2D, pname = GL_TEXTURE_WRAP_T, param = GL_REPEAT)
131 2517 glTexParameteri(target = GL_TEXTURE_2D, pname = GL_TEXTURE_MAG_FILTER, param = GL_NEAREST)
135 Note that one would expect call
2514 to be glTexImage(level=
9, width=
1,
136 height=
1) but it's not there.
140 The minification filter is GL_LINEAR_MIPMAP_LINEAR and the texture's
141 GL_TEXTURE_MAX_LEVEL is
1000 (the default) so a full mipmap is expected.
145 Later, these incomplete textures are bound before drawing calls.
146 According to the GL specification, if a fragment program or fragment shader
147 is being used, the sampler should return (
0,
0,
0,
1) (
"black") when sampling
148 from an incomplete texture.
149 This is what Mesa does and the resulting rendering is darker than it should
154 It appears that NVIDIA's driver (and possibly AMD's driver) detects this case
155 and returns (
1,
1,
1,
1) (white) which causes the rendering to appear brighter
156 and match the reference image (however, AMD's rendering is
<em>much
</em>
157 brighter than NVIDIA's).
161 If the fallback texture created in _mesa_get_fallback_texture() is
162 initialized to be full white instead of full black the rendering appears
164 However, we have no plans to implement this work-around in Mesa.
168 <h2>Maya-
03 test
2</h2>
171 This test makes some unusual calls to glRotate. For example:
174 glRotate(
50,
50,
50,
1);
175 glRotate(
100,
100,
100,
1);
176 glRotate(
52,
52,
52,
1);
179 These unusual values lead to invalid modelview matrices.
180 For example, the last glRotate command above produces this matrix with Mesa:
182 1.08536e+24 2.55321e-23 -
0.000160389 0
183 5.96937e-25 1.08536e+24 103408 0
184 103408 -
0.000160389 1.74755e+09 0
187 and with NVIDIA's OpenGL:
190 0 1.4013e-45 1.4013e-45 0
191 1.4013e-45 -nan
1.4013e-45 0
195 This causes the object in question to be drawn in a strange orientation
196 and with a semi-random color (between white and black) since GL_FOG is enabled.