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digitalmars.D.learn - No triangle with OpenGL (DerelictGLFW and DerelictGL3)

reply Peter Lewis <peter werl.me> writes:
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 

Any help is appreciated, Thanks!
Jun 11 2016
next sibling parent Joerg Joergonson <JJoergonson gmail.com> writes:
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 

 Any help is appreciated, Thanks!


I had similar issues when I tried it and never got it to work 
either.

Try Adam Druppe's stuff on github. It works and he has some 
support for images and stuff. It's not perfect but at least it 
works out of the box compared to alot of the other stuff floating 
around that mostly is outdated.
Jun 11 2016
prev sibling parent reply Mike Parker <aldacron gmail.com> writes:
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 

 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);
Jun 11 2016
parent Peter Lewis <peter werl.me> writes:
On Sunday, 12 June 2016 at 03:46:31 UTC, Mike Parker wrote:

 On Sunday, 12 June 2016 at 02:16:52 UTC, Peter Lewis wrote:

 [...]


 Your problem is this line:

 glBufferData(GL_ARRAY_BUFFER, verts.sizeof, &verts, 
 GL_STATIC_DRAW);

 [...]


Thank you very much. You are right, that fixed my issue
Jun 11 2016