# Lil_Lloyd

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1. ## My custom mem allocator isn't working because....

Eek! I have another issue now, and it shows my ignorance with pointers to pointers. I search through a linked list like so: //use two pointers to gague where the new ptr should go MallocStruct** ptr1 = NULL; MallocStruct** ptr2 = &freeListHeader; //case3 other wise needs to be inserted into a list somewhere... while(newFree > *ptr2){ ptr1 = ptr2; ptr2 = &((*ptr2)->next); //if next is NULL we need to go to case 4 - inserting at the end if(*ptr2 == NULL) break; }    Then, if I need to insert my new block, I insert it like so: // end of the list if(ptr2 == NULL){ (*ptr1)->next = newFree; newFree->prev = (*ptr1); }else if(ptr1 == NULL){ //beginning of the list (*ptr2)->prev = newFree; newFree->next = (*ptr2); (*ptr2) = newFree; }else{ //middle of the list (*ptr1)->next = newFree; newFree->next = (*ptr2); (*ptr2)->prev = newFree; newFree->prev = (*ptr1); }  The problem is the middle of the list insertion. I'm under the false assumption that (*ptr1)->next = newFree; merely changes the address that (*ptr1)->next points to, however it changes the value of *ptr2 too! How am I supposed to insert a node into a list like this?
2. ## Making a sliding puzzle

What you need to do is have many quads (tiles or squares in the puzzle) and have the main image as a texture. Then for the coordinates of the quads you also need texture coordinates between 0.0 and 1.0. As an example if I had four squares the texture coordinates of the top left square would be (0.0,0.0)---------(0.25,0.0) | | | | | | (0.0,0.25)--------(0.25,0.25) As the square moves around its screen coordinates will change but its texture coordinates will remain constant. I also made a sliding puzzle some time ago, you can see it under my projects here: http://www.lloydcrawley.com/projects/ at the bottom of the screen There is a github repo link there too if you want to look at the source code. Good luck!

Thank you!

5. ## Frustum culling - culling nearby objects?

You know I said this didn't work? Well, before I started normalising the planes properly it didn't. I tried it again last night and it worked PERFECTLY. However, it was only after agonising hours of experimentation that I decided to try this again. Including making a debug view from above with the bounding rectangles shown on screen. Taught me a few things though! Thanks. :)
6. ## Tutorial: an XBOX360 pad Class using GLFW

Well I can't remember clearly but last summer I tried using Xinput with GLFW and thought it was a pain, and found GLFW by itself easier to manage as long as I didn't want to use the shoulder triggers
7. ## Tutorial: an XBOX360 pad Class using GLFW

When I wrote the article (last summer) I was unaware that the left and right triggers thing was related to the drivers used by the o/s whilst apparently xInput uses some different drivers to most to read the input from the pad.    However you can install a driver from here that helps:  http://www.jonnys-place.com/index.php?topic=10495.0   The negative being every user of your game will need the driver. Unless I become a driver programmer and use such arcane wizardry instead of GLFW.
8. ## Frustum culling - culling nearby objects?

RENDERING A FRUSTUM   So I found some code on rendering a frustum in old school style fixed pipeline GL   void Frustum::DrawFrustum(){ mat4x4 temp = m_projMatrix * m_modView; mat4x4 inv = temp._inverse(); vec4 fr[8]= { // near vec4(-1, -1, -1, 1), vec4( 1, -1, -1, 1), vec4( 1, 1, -1, 1), vec4(-1, 1, -1, 1), // far vec4(-1, -1, 1, 1), vec4( 1, -1, 1, 1), vec4( 1, 1, 1, 1), vec4(-1, 1, 1, 1) }; // Transform all vertices: // multiply vertex array (fr) by matrix. result is transformed vertex array (tfr) for(int i = 0; i < 8; i++) fr[i] = inv * fr[i]; for (int i=0; i<8; i++) { fr[i].x /= fr[i].w; fr[i].y /= fr[i].w; fr[i].z /= fr[i].w; fr[i].w = 1.0f; } glColor3f(1.0f,0.0f,0.0f); glBegin(GL_LINES); glVertex4fv(&(fr[0][0])); glVertex4fv(&(fr[1][0])); glVertex4fv(&(fr[1][0])); glVertex4fv(&(fr[2][0])); glVertex4fv(&(fr[2][0])); glVertex4fv(&(fr[3][0])); glVertex4fv(&(fr[3][0])); glVertex4fv(&(fr[0][0])); glVertex4fv(&(fr[4][0])); glVertex4fv(&(fr[5][0])); glVertex4fv(&(fr[5][0])); glVertex4fv(&(fr[6][0])); glVertex4fv(&(fr[6][0])); glVertex4fv(&(fr[7][0])); glVertex4fv(&(fr[7][0])); glVertex4fv(&(fr[4][0])); glVertex4fv(&(fr[0][0])); glVertex4fv(&(fr[4][0])); glVertex4fv(&(fr[1][0])); glVertex4fv(&(fr[5][0])); glVertex4fv(&(fr[2][0])); glVertex4fv(&(fr[6][0])); glVertex4fv(&(fr[3][0])); glVertex4fv(&(fr[7][0])); glEnd(); }   It seems solid to me, and I have a new 'debug' mode where I detach the camera from the frustum and can control it from above in an orthographic view. However, I'm getting behaviour that is odd. There is no frustum being rendered but only odd lines of varying length depending on camera rotation and sometimes the line doesn't even render unless the camera is in a certain location. Bizarre.    Here's a video link/demo   http://www.youtube.com/watch?v=_Jw1luubvz0&feature=youtu.be
9. ## Frustum culling - culling nearby objects?

Well, vectors/points are things described by an x,y and z value so sometimes they can be easily confused at times unless you keep in mind except that vectors describe direction and magnitude and points, well, describe points in space! In 4d points and vectors the difference is the w component, points have a value of one and vectors have a value of zero, when you subtract a point from a point to get a vector the w component goes to zero as required.   As for testing points against planes as opposed to testing 'vectors' is that you do in fact test points such as corners of a cube etc. With that said, yes normalizing a point is indeed odd.
10. ## Frustum culling - culling nearby objects?

ALSO - this may be a noobish question, but when I test a point against a frustum plane, do I have to normalise the point? Or leave it as it is? Additionally I have been using points defined in WORLD SPACE. This is correct yes?
11. ## Frustum culling - culling nearby objects?

OK I just noticed something big, but fixing still hasn't solved the problem   void Frustum::NormalizePlane(int index){ float normFactor = m_planes[index][0] * m_planes[index][0] + m_planes[index][1] * m_planes[index][1] + m_planes[index][2] * m_planes[index][2]; m_planes[index] /= normFactor; }     Should have been   void Frustum::NormalizePlane(int index){ float normFactor = m_planes[index][0] * m_planes[index][0] + m_planes[index][1] * m_planes[index][1] + m_planes[index][2] * m_planes[index][2]; normFactor = glm::sqrt(normFactor); m_planes[index] /= normFactor; }   I was forgetting to squareroot the length! However I'm still getting weird errors... :(
12. ## Frustum culling - culling nearby objects?

Nope that didn't work, but thanks anyway!
13. ## Frustum culling - culling nearby objects?

Thanks, I'll try that. This project is causing me a lot of trouble over simple things I understood the theory behind, but actually implementing it is so deceptively frustrating.
14. ## Frustum culling - culling nearby objects?

I have a quadtree terrain, but nearby quads are being culled. Like so:   http://www.youtube.com/watch?v=b8ztYDkO_28&feature=youtu.be   I was thinking maybe its my frustum extraction code? This is in OpenGL by the way in case matrix layout has any bearing on the problem and I am using the glm mat4x4 and vec4 types to represent my projection matrices and frustum planes    void Frustum::Extract(const vec3& eye,const mat4x4& camMatrix) { m_pos = eye; m_modView = camMatrix; m_projMatrix = GraphicsApp::GetInstance()->GetProjection(); mat4x4 MVPMatrix = m_projMatrix * m_modView; for(int plane = 0; plane < 3; plane ++){ int index = plane * 2; m_planes[index] = MVPMatrix[3] - MVPMatrix[plane]; NormalizePlane(index); } for(int plane = 0; plane < 3; plane ++){ int index = plane * 2 + 1; m_planes[index] = MVPMatrix[3] + MVPMatrix[plane]; NormalizePlane(index); } } void Frustum::NormalizePlane(int index){ float normFactor = m_planes[index][0] * m_planes[index][0] + m_planes[index][1] * m_planes[index][1] + m_planes[index][2] * m_planes[index][2]; m_planes[index] /= normFactor; }