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POGlowing/halo effect on cube mesh using TGA file
 

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  1. POGlowing/halo effect on cube mesh using TGA file
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    <p>First of all, we (my friends and I) are working on a Computer Graphics project where we are supposed to simulate particles (in our case, small cubes (mesh3d)) that would interact with each other in a space context. This is, hundreds of particles exploding and attracting each others using physics laws.</p> <p>We based our implementation on a framework provided from our school, so we have to "adapt ourselves" to it. </p> <p>While creating the cube (mesh3d), we provide a material containing a texture. </p> <pre><code>Mesh3D* SolarViewer:: createCube() { // initialize Mesh3D Mesh3D *cube = new Mesh3D(); MeshMaterial* mat = new MeshMaterial; //we create the material for the cube mat-&gt;m_diffuseTexture.create("particle.tga"); //we create the diffuse texture of the material to be particle.tga // setup uniform cube with side length 0.5 and center of cube being (0,0,0) std::vector&lt; Vector3 &gt; cubeVertices; std::vector&lt; Vector3 &gt; cubeNormals; std::vector&lt; Vector3 &gt; cubeColors; std::vector&lt; unsigned int &gt; cubeIndices; float d = 1.0; // front cubeVertices.push_back(Vector3(-d,-d, d)); cubeVertices.push_back(Vector3( d,-d, d)); cubeVertices.push_back(Vector3( d, d, d)); cubeVertices.push_back(Vector3(-d, d, d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(0,0,1)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.8,0.3,0.3)); cubeIndices.push_back(0); cubeIndices.push_back(1); cubeIndices.push_back(2); cubeIndices.push_back(0); cubeIndices.push_back(2); cubeIndices.push_back(3); // right cubeVertices.push_back(Vector3( d,-d,-d)); cubeVertices.push_back(Vector3( d,-d, d)); cubeVertices.push_back(Vector3( d, d, d)); cubeVertices.push_back(Vector3( d, d,-d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(1,0,0)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.3,0.8,0.3)); cubeIndices.push_back(4); cubeIndices.push_back(5); cubeIndices.push_back(6); cubeIndices.push_back(4); cubeIndices.push_back(6); cubeIndices.push_back(7); // back cubeVertices.push_back(Vector3( d,-d,-d)); cubeVertices.push_back(Vector3(-d,-d,-d)); cubeVertices.push_back(Vector3(-d, d,-d)); cubeVertices.push_back(Vector3( d, d,-d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(0,0,-1)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.3,0.3,0.8)); cubeIndices.push_back(8); cubeIndices.push_back(9); cubeIndices.push_back(10); cubeIndices.push_back(8); cubeIndices.push_back(10); cubeIndices.push_back(11); // left cubeVertices.push_back(Vector3(-d,-d, d)); cubeVertices.push_back(Vector3(-d,-d,-d)); cubeVertices.push_back(Vector3(-d, d,-d)); cubeVertices.push_back(Vector3(-d, d, d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(-1,0,0)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.8,0.8,0.3)); cubeIndices.push_back(12); cubeIndices.push_back(13); cubeIndices.push_back(14); cubeIndices.push_back(12); cubeIndices.push_back(14); cubeIndices.push_back(15); // top cubeVertices.push_back(Vector3(-d, d,-d)); cubeVertices.push_back(Vector3( d, d,-d)); cubeVertices.push_back(Vector3( d, d, d)); cubeVertices.push_back(Vector3(-d, d, d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(0,1,0)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.8,0.3,0.8)); cubeIndices.push_back(16); cubeIndices.push_back(17); cubeIndices.push_back(18); cubeIndices.push_back(16); cubeIndices.push_back(18); cubeIndices.push_back(19); // bottom cubeVertices.push_back(Vector3( d,-d,-d)); cubeVertices.push_back(Vector3(-d,-d,-d)); cubeVertices.push_back(Vector3(-d,-d, d)); cubeVertices.push_back(Vector3( d,-d, d)); for(int k = 0; k &lt; 4; k++) cubeNormals.push_back(Vector3(0,-1,0)); for(int k = 0; k &lt; 4; k++) cubeColors.push_back(Vector3(0.3,0.8,0.8)); cubeIndices.push_back(20); cubeIndices.push_back(21); cubeIndices.push_back(22); cubeIndices.push_back(20); cubeIndices.push_back(22); cubeIndices.push_back(23); cube-&gt;setIndices(cubeIndices, mat); //we set the cubeIndices and the material for the cube cube-&gt;setVertexPositions(cubeVertices); cube-&gt;setVertexNormals(cubeNormals); cube-&gt;setVertexColors(cubeColors); return cube; } </code></pre> <p>and then we iterate through all of our cubes in the draw scene method in order to draw them</p> <pre><code>for (std::vector&lt;Mesh3D*&gt;::iterator mIt = m_meshes.begin(); mIt != m_meshes.end(); ++mIt) { Mesh3D* cube = *mIt; m_meshShaderTexture.setMatrix4x4Uniform("modelworld", cube-&gt;getTransformation()); cube-&gt;getMaterial(0).m_diffuseTexture.bind(); m_meshShaderTexture.setIntUniform("texture", cube-&gt;getMaterial(0).m_diffuseTexture.getLayer()); draw_object(m_meshShaderTexture, cube);// method called to draw the cube } </code></pre> <p>We called this line in the method "drawObject" which has for purpose to draw the mesh3d objects : </p> <pre><code> void SolarViewer::draw_object(Shader&amp; sh, Mesh3D *mesh) { sh.setMatrix4x4Uniform("modelworld", mesh-&gt;getTransformation() ); glEnableClientState(GL_VERTEX_ARRAY); glEnableClientState(GL_NORMAL_ARRAY); glEnableClientState(GL_TEXTURE_COORD_ARRAY); glVertexPointer( 3, GL_DOUBLE, 0, mesh-&gt;getVertexPointer() ); glNormalPointer( GL_DOUBLE, 0, mesh-&gt;getNormalPointer() ); glTexCoordPointer( 2, GL_DOUBLE, 0, mesh-&gt;getUvTextureCoordPointer() ); for(unsigned int i = 0; i &lt; mesh-&gt;getNumberOfParts(); i++) { glDrawElements( GL_TRIANGLES, mesh-&gt;getNumberOfFaces()*3, GL_UNSIGNED_INT, mesh-&gt;getVertexIndicesPointer() ); } glDisableClientState(GL_NORMAL_ARRAY); glDisableClientState(GL_VERTEX_ARRAY); glDisableClientState(GL_TEXTURE_COORD_ARRAY); } </code></pre> <p>But at the end, while trying to compile, the following line gives us a BAD_ACCESS :(</p> <pre><code>glDrawElements( GL_TRIANGLES, mesh-&gt;getNumberOfFaces()*3, GL_UNSIGNED_INT, mesh-&gt;getVertexIndicesPointer() ); </code></pre> <p>What are we doing wrong ? Is it enough to bind the following texture (.tga) to have the glowing effect ? : <a href="http://i166.photobucket.com/albums/u83/j1m68/star.jpg" rel="nofollow">http://i166.photobucket.com/albums/u83/j1m68/star.jpg</a></p>
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    1. PTQuestion
    1. USgenpfault
    1. USFloran Gmehlin
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      1. POGlowing/halo effect on cube mesh using TGA file
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      1. VTUpMod
    1. COLooks right to me (although you could use a number of techniques to speed things up). What does mesh->getNumberOfParts(), mesh->getNumberOfFaces(), etc return? Looks like they might be the cause of your problem.
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      1. POGlowing/halo effect on cube mesh using TGA file
      1. USAni
    2. COIn the actual state before the bad_access, we have the following output : `mesh number of parts : 1` `mesh number of faces : 12` These are, the number of faces of the mesh (although i do not get it why it is 12 instead of 6, for a cube) and number of part, I don0t really know :/ As I said, we used a framework that was provided, so there are some things we have no idea about -.- ...
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      1. POGlowing/halo effect on cube mesh using TGA file
      1. USFloran Gmehlin
    3. COWell - there you have it. If mesh->getNumberOfFaces() is already 12, mesh->getNumberOfFaces() * 3 = 36 which means OpenGL expects many more indices and vertices in the arrays you specified and therefore you're getting an access violation. If you replace "mesh->getNumberOfFaces() * 3" with "mesh->getNumberOfFaces()", it ought to be ok. Remember - that argument is number of primitives (triangles). If that fixes it - I'll suggest it as an answer you can accept.
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      1. POGlowing/halo effect on cube mesh using TGA file
      1. USAni
 

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