On Sunday, 12 June 2016 at 02:16:52 UTC, Peter Lewis wrote:
Hi all.
I am trying to create a basic OpenGL triangle in a GLFW
instance. The window works, I can change the background colour
and everything but for the life of me I can't get the triangle
to show up. Instead of trying to put everything in the post, I
have put it on github. (https://github.com/werl/d_glfw_tests) I
am currently following a tutorial I found
(http://learnopengl.com/#!Getting-started/Hello-Triangle).
Any help is appreciated, Thanks!
Your problem is this line:
glBufferData(GL_ARRAY_BUFFER, verts.sizeof, &verts,
GL_STATIC_DRAW);
First, the array declarations in the example C code create static
arrays. Calling sizeof(array) on a static array in C will give
you the combined size of all the elements. For a dynamic array,
it will give you the size of a pointer.
The same is true in D, but there's a difference in the
declaration syntax. float[9] foo; is a static array, but float[]
bar; is *always* a dynamic array. foo.size of will give you 36.
bar.size of will give you 8 in 32-bit and 16 in 64-bit, because
its giving you the size of the length and pointer that make up
the array itself, not of the contents.
Second, &verts is giving you a pointer to the array itself (i.e.
the length and pointer pair) and *not* the contents. D arrays are
not C arrays!
With the two changes below, your triangle renders fine.
glBufferData(GL_ARRAY_BUFFER, verts.length * float.sizeof,
verts.ptr, GL_STATIC_DRAW);
