2 files changed, 97 insertions, 1 deletions

diff --git a/copy_experiments/Makefile b/copy_experiments/Makefile
index ede22dc..5adda53 100644
--- a/copy_experiments/Makefile
+++ b/copy_experiments/Makefile
@@ -1,5 +1,6 @@
 .PHONY: all clean
 NVCC ?= nvcc
+CC ?= gcc
 
 all: copy_contender mon_cross_ctx_copies
 
@@ -9,5 +10,8 @@ copy_contender: copy_contender.cu copy_testbench.h ../testbench.h
 mon_cross_ctx_copies: mon_cross_ctx_copies.cu copy_testbench.h ../testbench.h
         $(NVCC) mon_cross_ctx_copies.cu -o $@ -lcuda -lpthread -g
 
+gl_copies: gl_copies.c
+        $(CC) gl_copies.c -o $@ -lGL -lglut -g
+
 clean:
-        rm -f copy_contender mon_cross_ctx_copies
+        rm -f copy_contender mon_cross_ctx_copies gl_copies
diff --git a/copy_experiments/gl_copies.c b/copy_experiments/gl_copies.c
new file mode 100644
index 0000000..4d6de1f
--- /dev/null
+++ b/copy_experiments/gl_copies.c
@@ -0,0 +1,92 @@
+// Built off the Triangle and Checkered Triangle OpenGL examples by Ray Toal
+// (https://cs.lmu.edu/~ray/notes/openglexamples/)
+#include <stdio.h>
+
+#include <GL/glut.h>
+
+#define red {0xff, 0x00, 0x00}
+#define yellow {0xff, 0xff, 0x00}
+#define magenta {0xff, 0, 0xff}
+
+GLubyte* texture;
+
+const unsigned side = 1024*10; // 30 MiB
+
+// Clears the current window and draws a triangle.
+void display() {
+
+  // Set every pixel in the frame buffer to the current clear color.
+  glClear(GL_COLOR_BUFFER_BIT);
+
+  // Re-upload the texture on every frame
+  glTexSubImage2D(GL_TEXTURE_2D, 0, 0, 0, side, side, GL_RGB, GL_UNSIGNED_BYTE, texture);
+
+  // Drawing is done by specifying a sequence of vertices.  The way these
+  // vertices are connected (or not connected) depends on the argument to
+  // glBegin.  GL_POLYGON constructs a filled polygon.
+  glBegin(GL_POLYGON);
+  glTexCoord2f(0.5, side); glVertex3f(-0.6, -0.75, 0.5);
+  glTexCoord2f(0.0, 0.0); glVertex3f(0.6, -0.75, 0);
+  glTexCoord2f(side, 0.0); glVertex3f(0, 0.75, 0);
+  glEnd();
+
+  // Flush drawing command buffer to make drawing happen as soon as possible.
+  glFlush();
+
+  // Request a redraw on the next loop
+  glutPostRedisplay();
+}
+
+// Initializes GLUT, the display mode, and main window; registers callbacks;
+// enters the main event loop.
+int main(int argc, char** argv) {
+  // No arguments are accepted
+  if (argc != 1) {
+    fprintf(stderr, "Usage: %s\n", argv[0]);
+    return 1;
+  }
+
+  // 30 MiB image
+  texture = malloc(side*side*3u);
+
+  // Add a checkered pattern to the texture
+  for (unsigned i = 0; i < side*side; i++) {
+    if (i % 2 == 0) { // Yellow
+      texture[i*3] = 0xff;
+      texture[i*3+1] = 0xff;
+    } else // Red
+      texture[i*3] = 0xff;
+  }
+
+  // Use a single buffered window in RGB mode (as opposed to a double-buffered
+  // window or color-index mode).
+  glutInit(&argc, argv);
+  glutInitDisplayMode(GLUT_SINGLE | GLUT_RGB);
+
+  // Position window at (80,80)-(480,380) and give it a title.
+  glutInitWindowPosition(80, 80);
+  glutInitWindowSize(400, 300);
+  glutCreateWindow("A Simple Triangle");
+
+  // Tell GLUT that whenever the main window needs to be repainted that it
+  // should call the function display().
+  glutDisplayFunc(display);
+
+  glEnable(GL_TEXTURE_2D);
+  glPixelStorei(GL_UNPACK_ALIGNMENT, 1);
+  glTexImage2D(GL_TEXTURE_2D,
+               0,                    // level 0
+               3,                    // use only R, G, and B components
+               side, side,           // texture has 2x2 texels
+               0,                    // no border
+               GL_RGB,               // texels are in RGB format
+               GL_UNSIGNED_BYTE,     // color components are unsigned bytes
+               texture);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
+  glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
+
+  // Tell GLUT to start reading and processing events.  This function
+  // never returns; the program only exits when the user closes the main
+  // window or kills the process.
+  glutMainLoop();
+}