Teartest with -o flag to specify override redirect window and -r number to specify refresh rate.

client/deps/glbench/src/teartest.cc

+// Copyright (c) 2010 The Chromium OS Authors. All rights reserved.
+// Use of this source code is governed by a BSD-style license that can be
+// found in the LICENSE file.
+
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <time.h>
+
+#include "main.h"
+#include "utils.h"
+
+
+GLuint GenerateAndBindTexture() {
+  GLuint name = ~0;
+  glGenTextures(1, &name);
+  glBindTexture(GL_TEXTURE_2D, name);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
+  return name;
+}
+
+
+char *CreateBitmap(int w, int h) {
+  char *bitmap = new char[w * h];
+  memset(bitmap, 255, w * h);
+  memset(bitmap + w * (1 + h / 2), 0, w);
+  memset(bitmap + w * (5 + h / 2), 0, w);
+  return bitmap;
+}
+
+
+const char *vertex_shader =
+    "attribute vec4 c;"
+    "uniform float shift;"
+    "void main() {"
+    "    gl_Position = c;"
+    "    gl_TexCoord[0] = vec4(c.y, c.x - shift, 0.0, 0.0);"
+    "}";
+
+const char *fragment_shader =
+    "uniform sampler2D tex;"
+    "void main() {"
+    "    gl_FragColor = texture2D(tex, gl_TexCoord[0].xy);"
+    "}";
+
+
+// If refresh is set to zero, we enable vsync.  Otherwise we redraw that many
+// times a second.
+struct timespec* g_sleep_duration = NULL;
+static void ParseArgs(int argc, char* argv[]) {
+  bool refresh_arg = false;
+  for (int i = 0; i < argc; i++) {
+    if (refresh_arg) {
+      refresh_arg = false;
+
+      int refresh = atoi(argv[i]);
+      if (refresh > 1) {
+        delete g_sleep_duration;
+        g_sleep_duration = new struct timespec;
+        g_sleep_duration->tv_sec = 0;
+        g_sleep_duration->tv_nsec = static_cast<long>(1.e9 / refresh);
+      } else {
+        printf("-r requires integer greater than one.\n");
+      }
+    } else if (strcmp("-o", argv[i]) == 0) {
+      g_override_redirect = false;
+      printf("blah\n");

[piman, 2010/03/12 22:52:11]

bleh.

+    } else if (strcmp("-r", argv[i]) == 0) {
+      refresh_arg = true;
+    }
+  }
+}
+
+
+int main(int argc, char* argv[]) {
+  ParseArgs(argc, argv);
+  g_height = -1;
+  if (!Init()) {
+    printf("# Failed to initialize.\n");
+    return 1;
+  }
+
+  InitContext();
+  glViewport(-g_width, -g_height, g_width*2, g_height*2);
+
+  char *bitmap = CreateBitmap(g_height, g_width*2);
+  GLuint texture = GenerateAndBindTexture();
+  glTexImage2D(GL_TEXTURE_2D, 0, GL_LUMINANCE, g_height, g_width, 0,
+               GL_LUMINANCE, GL_UNSIGNED_BYTE, bitmap + g_height * g_width);
+
+  GLfloat vertices[8] = {
+    0.f, 0.f,
+    1.f, 0.f,
+    0.f, 1.f,
+    1.f, 1.f,
+  };
+
+  GLuint program = InitShaderProgram(vertex_shader, fragment_shader);
+  int attribute_index = glGetAttribLocation(program, "c");
+  glVertexAttribPointer(attribute_index, 2, GL_FLOAT, GL_FALSE, 0, vertices);
+  glEnableVertexAttribArray(attribute_index);
+
+  int texture_sampler = glGetUniformLocation(program, "tex");
+  glUniform1f(texture_sampler, 0);
+
+  int shift_uniform = glGetUniformLocation(program, "shift");
+  int i = 0;
+  // TODO: do something clever to set use_vsync.

[piman, 2010/03/12 22:52:11]

You can remove the TODO

+  SwapInterval(g_sleep_duration ? 0 : 1);
+  for (;;) {
+    glClear(GL_COLOR_BUFFER_BIT);
+    glUniform1f(shift_uniform, 1.f / g_width *
+                (i < g_width ? i : 2 * g_width - i));
+    i = (i + 4) % (2 * g_width);
+    glDrawArrays(GL_TRIANGLE_STRIP, 0, 4);
+    glFlush();
+
+    if (g_sleep_duration)
+      nanosleep(g_sleep_duration, NULL);
+
+    SwapBuffers();
+  }
+
+  glDeleteTextures(1, &texture);
+  DestroyContext();
+  return 0;
+}