Databases
StackOverflow2013
Postsdbo
PO
 

Note that there are some explanatory texts on larger screens.

plurals
  1. PO
    primarykey
    data
    text
    <p>There is no pointer arithmetic for <code>void*</code> pointers. Use <code>char*</code> pointers to perform byte-wise pointer computations.</p> <p>Or a lot better than that: Use the <em>real</em> type the pointer is pointing to, and don't multiply offsets. Simply write <code>vertex[index+base]</code> assuming <code>vertex</code> points to your type containing 28 bytes of data.</p> <p><strong>Performance consideration:</strong> Align your vertex attributes to a power of two for coalesced memory access. This means, add 4 bytes of padding after each vertex entry. To automatically do this, use <code>float8</code> as the vertex type if your attributes are all floating point values. I assume you work with position and normal data or something similar, so it might be a good idea to write a custom struct which encapsulates both vectors in a convenient and self-explaining way:</p> <pre class="lang-opencl prettyprint-override"><code>// Defining a type for the vertex data. This is 32 bytes large. // You can share this code in a header for inclusion in both OpenCL and C / C++! typedef struct { float4 pos; float4 normal; } VertexData; // Example kernel __kernel void computeNormalKernel(__global VertexData *vertex, uint base) { uint index = get_global_id(0); VertexData thisVertex = vertex[index+base]; // It can't be simpler! thisVertex.normal = computeNormal(...); // Like you'd do it in C / C++! vertex[index+base] = thisVertex; // Of couse also when writing } </code></pre> <p>Note: This code doesn't work with your stride of 28 if you just change one of the <code>float4</code>s to a <code>float3</code>, since <code>float3</code> also consumes 4 floats of memory. But you can write it like this, which will not add padding (but note that this will penalize memory access bandwidth):</p> <pre><code>typedef struct { float pos[4]; float normal[3]; // Assuming you want 3 floats here } VertexData; </code></pre>
    singulars
    1. This table or related slice is empty.
    1. POOpenCL void pointer arithmetic - strange behavior
      singulars
      1. PTQuestion
    1. PTAnswer
    1. USleemes
    1. USleemes
    plurals
    1. This table or related slice is empty.
    1. This table or related slice is empty.
    1. POOpenCL void pointer arithmetic - strange behavior
      singulars
      1. PTQuestion
    1. This table or related slice is empty.
    1. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    2. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTUpMod
    3. VO
      singulars
      1. PO
      1. This table or related slice is empty.
      1. VTAcceptedByOriginator
    1. COthanks for you answer :) But does opengl do some automatic buffer alignment or something like that? I am using an vertex type array now just as you said, but I still get wrong values.. When I am using `VertexType vertex1 = vertices_gl[indices.x+base];` in OpenCL I get wrong values, but when I am doing the same in my C++ program (using the raw pointer to the same buffer) I get the correct result
      singulars
      1. PO
      1. USAurus
    2. COokay turned out that printf is just printing the wrong values :(
      singulars
      1. PO
      1. USAurus
    3. COSo it works now? Just remember: When aligning your attributes, make sure you use the same alignment on the host, in OpenCL and in OpenGL.
      singulars
      1. PO
      1. USleemes
 

Querying!

 
Guidance
A row detail

Detail views are divided into sections. All the information in the data section comes from columns in the selected row. The other sections display data from other, related rows.

Related data can be related in a to-one or a to-many fashion. Captions of data related in a to-many fashion link to a list view showing a filtered view of the table.

Try moving around until you find a non-empty to-many entry and click on the label to get to one. You can move back to the root by clicking on the database name in the header.

SQuiL has stopped working due to an internal error.

If you are curious you may find further information in the browser console, which is accessible through the devtools (F12).

Reload