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OpenGL 1D Texture to span 2D Quad

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In order to avoid "P=NP" style programming challenge (aka, box-sorting algorithm), I made my texture 1D (even though it should be 2D). Basically, I grab several Bitmaps, play around with the pixels until each are of long 1 pixel thin (contiguous) line, and then shove them all into a 1D Texture. In past, I do this (for when using 2D Texture):
cGL.glBegin(cGL.GL_QUADS);

cGL.glColor4ub(TheColor.MyR, TheColor.MyG, TheColor.MyB, TheColor.MyA);

cGL.glTexCoord2f(TheTextureX1, TheTextureY1);
cGL.glVertex2i(TheDstX, TheDstY);

cGL.glTexCoord2f(TheTextureX2, TheTextureY1);
cGL.glVertex2i(TheDstX + TheSrcWidth, TheDstY);

cGL.glTexCoord2f(TheTextureX2, TheTextureY2);
cGL.glVertex2i(TheDstX + TheSrcWidth, TheDstY + TheSrcHeight);

cGL.glTexCoord2f(TheTextureX1, TheTextureY2);
cGL.glVertex2i(TheDstX, TheDstY + TheSrcHeight);

cGL.glEnd();
cGL.sCheckOpenGLError();


But now I need to change that "glTexCoord2f" to "1f" (or 1d). And I'm not sure what values to put in it.

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It cannot be done in any sane way. If you want a 2D texture, what's wrong with a 2D texture?

I may be possible to achieve some kind of result if and only if the only thing you're drawing is a screen aligned quad whose size in pixel matches exactly that of the 2D sub-texture...

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Quote:
Original post by Brother Bob
It cannot be done in any sane way. If you want a 2D texture, what's wrong with a 2D texture?


It was Julian's recommendation on #gamedev two months ago that I use a 1D Texture to save myself from having to write a box-sorting algorithm for my hardware wrapper. Basically, my code allows the user to play with OpenGL as if it were GDI (aka, none of this power of 2 crap, or minimizing texture binds).

My code takes in any sized bitmap, and shoves it into VRAM (if the bitmap is larger than a texture, it will automatically make rendering it consider of multiple renders from different textured quads, and if the bitmap is small enough to fit onto an existing allocated texture (average case), it will simply shove it on it).

Because the user doesn't have to be concerned with how the textures are stored in VRAM, fragmentation (subtextures removed, and replaced with new ones) is very prone to occur. And by using a 1D texture, it becomes very easy to deal with.

Quote:
Original post by Brother Bob
I may be possible to achieve some kind of result if and only if the only thing you're drawing is a screen aligned quad whose size in pixel matches exactly that of the 2D sub-texture...


Yes, that holds. My wrapper cannot even do linear-filtering. A pixel on the texture will correspond to a pixel on the screen (or a natural integer power of 2 multiple; for instance, 1x 2x 4x 8x GL_NEAREST zooming) always.

What's your idea?

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Quote:
Original post by Thevenin
Yes, that holds. My wrapper cannot even do linear-filtering. A pixel on the texture will correspond to a pixel on the screen (or a natural integer power of 2 multiple; for instance, 1x 2x 4x 8x GL_NEAREST zooming) always.

What's your idea?

May be possible, but with 1x zoom only. I cannot see a solution with any other zoom at all. I had an initial idea though, but it failed because the necessary texture coordinates became non-planar and the interpolation failed.

The problem, really, is that you require two degrees of freedom in your interpolation, but you only have one interpolation factor. Concider this case as an example. You have a 2x2 texel 2D texture stuck in a 4 texel 1D texture, like this.

| A B |
2D = | | --> 1D = | A B C D |
| C D |

Sampling the texture between A and B is a matter of interpolating between A and B along the X-axis, which works in the 1D texture also. Sampling between A and C gives you B in the 1D texture though...

edit: Oh, and in case you wasn't aware of it, that "non-power of two only crap" was removed from the specification three and a half years ago.

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Alright, my solution is evidently "no go". Damn Julian and his (her?) misunderstanding of what it was I was trying to do! All the code I wrote this morning (for resolving when to shift around fragments in 1D) is useless now... [bawling]

Code Written This Morning

using System;
using System.Collections.Generic;
using System.Text;
using System.Drawing;
using System.IO;
using cMinimalDeps;

namespace FrostWindow
{
struct aVRAMSlot
{
public int MyIndex;
public int MyLength;
public cVRAMCylinder MyTexture;
public int MyFrequency; /* Number of times used in 100 frames. */

public aVRAMSlot(int TheIndex, int TheLength, cVRAMCylinder TheTexture)
{
this.MyIndex = TheIndex;
this.MyLength = TheLength;
this.MyTexture = TheTexture;
this.MyFrequency = 0;
}
}

internal class cVRAMCylinder
{
public aColor[] MyPixels = null;
public int MyTextureID = -1;

public cVRAMCylinder()
{
MyPixels = new aColor[cGL.MyTextureSize];
sLoad();
}
public void sLoad()
{
if (MyTextureID != -1)
throw new Exception("Texture is already loaded. Call sUnload() before sLoad()!");
MyTextureID = cGL.glGenerateTexture(MyPixels);
}
public void sUnload()
{
/* glDeleteTextures silently ignores 0's and names that do not
correspond to existing textures.
-- http://www.opengl.org/documentation/specs/man_pages/hardcopy/GL/html/gl/deletetextures.html
*/

cGL.glDeleteTexture(MyTextureID);
MyTextureID = -1;
}
}

public class cFrostTex : IDisposable
{
internal aVRAMSlot[] MyComposition = null;
public int MyWidth = 0;
public int MyHeight = 0;

public cFrostTex(int TheWidth, int TheHeight) : this(TheWidth, TheHeight, null) { }
public cFrostTex(int TheWidth, int TheHeight, aColor[] ThePixels)
{
if (TheWidth <= 0 || TheHeight <= 0)
throw new Exception("Width and Height must both be greater than 0.");

this.MyWidth = TheWidth;
this.MyHeight = TheHeight;
MyComposition = cVRAM.sNewTexture(TheWidth, TheHeight);

if (ThePixels != null)
{
for (int TheLoopX = 0; TheLoopX < MyWidth; TheLoopX++)
for (int TheLoopY = 0; TheLoopY < MyHeight; TheLoopY++)
sSetPixel(TheLoopX, TheLoopY, ThePixels[(TheLoopY * TheWidth) + TheLoopX]);
}

/* Write this to the VRAM. */
sRefresh();
}

public aColor sGetPixel(int TheX, int TheY)
{
int ThePixelAccessed = (MyWidth * TheY) + TheX;
int TheOffset = 0;

/* This code uses a loop and alot of reference lookups just to get a single pixel on system RAM. :/ */
for (int TheCylinderLoop = 0; TheCylinderLoop < MyComposition.Length; TheCylinderLoop++)
{
if (TheOffset + MyComposition[TheCylinderLoop].MyLength < ThePixelAccessed)
TheOffset += MyComposition[TheCylinderLoop].MyLength;
else
return MyComposition[TheCylinderLoop].MyTexture.MyPixels[ThePixelAccessed - TheOffset];
}

/* If we've gotten here, something terrible has happened. */
throw new Exception("Could not find requested pixel in texture.");
}

public void sDraw(int TheSrcX, int TheSrcY, int TheSrcWidth, int TheSrcHeight,
int TheDstX, int TheDstY, aRect TheClipping, aColor TheColor)
{


/* Ok, so basically, there may be mulitiple renders here, depending on how many cylinders were used. */
for (int TheLoop = 0; TheLoop < MyComposition.Length; TheLoop++)
{
/* Calculate the actual position of the*/
float TheTextureX1 = (float)TheSrcX / cGL.MyTextureSize;
float TheTextureY1 = (float)TheSrcY / cGL.MyTextureSize;

float TheTextureX2 = (float)(TheSrcX + TheSrcWidth) / cGL.MyTextureSize;
float TheTextureY2 = (float)(TheSrcY + TheSrcHeight) / cGL.MyTextureSize;



if (!TheTexture.MyOnVRAM) throw new Exception("Trying to render texture that isn't on VRAM.");
if (MyCurrentBoundTexture != TheTexture.MyTexture)
{
cGL.glBindTexture(cGL.GL_TEXTURE_1D, TheTexture.MyTexture);
MyCurrentBoundTexture = TheTexture.MyTexture;
}

cGL.glBegin(cGL.GL_QUADS);

cGL.glColor4ub(TheColor.MyR, TheColor.MyG, TheColor.MyB, TheColor.MyA);

cGL.glTexCoord2f(TheTextureX1, TheTextureY1);
cGL.glVertex2i(TheDstX, TheDstY);

cGL.glTexCoord2f(TheTextureX2, TheTextureY1);
cGL.glVertex2i(TheDstX + TheSrcWidth, TheDstY);

cGL.glTexCoord2f(TheTextureX2, TheTextureY2);
cGL.glVertex2i(TheDstX + TheSrcWidth, TheDstY + TheSrcHeight);

cGL.glTexCoord2f(TheTextureX1, TheTextureY2);
cGL.glVertex2i(TheDstX, TheDstY + TheSrcHeight);

cGL.glEnd();
cGL.sCheckOpenGLError();
}
}

public void sSetPixel(int TheX, int TheY, aColor TheColor)
{
cVRAM.sSetPixel(this, TheColor,TheX,TheY);
}
public void sRefresh()
{
cVRAM.sRefreshCylinders(this.MyComposition);
}

/* For debug support. */
public Bitmap sToBitmap()
{
/* Create a bitmap, and set pixel it. */
Bitmap TheBitmap = new Bitmap(cGL.MyTextureSize, cGL.MyTextureSize);
for (int TheLoopX = 0; TheLoopX < cGL.MyTextureSize; TheLoopX++)
for (int TheLoopY = 0; TheLoopY < cGL.MyTextureSize; TheLoopY++)
{
aColor TheColor = sGetPixel(TheLoopX, TheLoopY);
TheBitmap.SetPixel(TheLoopX, TheLoopY, Color.FromArgb(TheColor.MyA,
TheColor.MyR, TheColor.MyG, TheColor.MyB));
}
return TheBitmap;
}

void IDisposable.Dispose()
{
cVRAM.sDisposeTexture(this);
}
}

internal static class cVRAM
{
/* Graphics handling. */
public static int MyBlitCount = 0;
private static int MyCurrentBoundTexture = -1;

/* All of the VRAM cartridges are 1D, and are listed here. The Cylinder also contains RAM backup of their pixel data. */
static List<cVRAMCylinder> MyCylinders = new List<cVRAMCylinder>();

/* As we pull cFrostTexs out of RAM, we are going to end up with fragmentations. */
static List<aVRAMSlot> MyFragments = new List<aVRAMSlot>();

public static aVRAMSlot[] sNewTexture(int TheWidth, int TheHeight)
{
int ThePixelsRemaining = TheWidth * TheHeight;
List<aVRAMSlot> TheReturn = new List<aVRAMSlot>();

while (ThePixelsRemaining != 0)
{

/* Take the place of any fragments first! */
for (int TheLoop = 0; TheLoop < MyFragments.Count; TheLoop++)
{
aVRAMSlot TheSlot = MyFragments[TheLoop];

/* If we need the entire slot, then take it. */
if (TheSlot.MyLength <= ThePixelsRemaining)
{
TheReturn.Add(TheSlot);
MyFragments.Remove(TheSlot);
ThePixelsRemaining -= TheSlot.MyLength;
}
/* Else if we only need a little bit of it. */
else if (ThePixelsRemaining != 0)
{
MyFragments.Remove(TheSlot);

/* Build the remaining slot, and add it. */
aVRAMSlot TheRemainingSlot = new aVRAMSlot();
TheRemainingSlot.MyIndex = TheSlot.MyIndex + ThePixelsRemaining;
TheRemainingSlot.MyLength = TheSlot.MyLength - ThePixelsRemaining;
TheRemainingSlot.MyTexture = TheSlot.MyTexture;
MyFragments.Add(TheRemainingSlot);

/* Add what we took, to the return. */
aVRAMSlot TheWhatWeUsed = new aVRAMSlot();
TheWhatWeUsed.MyIndex = TheSlot.MyIndex;
TheWhatWeUsed.MyLength = ThePixelsRemaining;
TheWhatWeUsed.MyTexture = TheSlot.MyTexture;
TheReturn.Add(TheWhatWeUsed);
}
}

/* If after the fragments have been used, there still isn't enough room for the texture,
* build a new cylinder, and subsequently another (huge) fragment. */

if (ThePixelsRemaining != 0)
{
cVRAMCylinder TheNewCylinder = new cVRAMCylinder();
MyCylinders.Add(TheNewCylinder);
MyFragments.Add(new aVRAMSlot(0, cGL.MyTextureSize, TheNewCylinder));
}
}
return TheReturn.ToArray();
}

internal static void sSetPixel(cFrostTex TheTexture, aColor ThePixel, int TheX, int TheY)
{
int ThePixelAccessed = (TheTexture.MyWidth * TheY) + TheX;
int TheOffset = 0;

/* This code uses a loop and alot of reference lookups just to place a single pixel on system RAM. :/ */
for(int TheCylinderLoop = 0; TheCylinderLoop<TheTexture.MyComposition.Length; TheCylinderLoop++)
{
if(TheOffset + TheTexture.MyComposition[TheCylinderLoop].MyLength < ThePixelAccessed)
TheOffset += TheTexture.MyComposition[TheCylinderLoop].MyLength;
else
{
TheTexture.MyComposition[TheCylinderLoop].MyTexture.MyPixels[ThePixelAccessed - TheOffset] = ThePixel;
return;
}
}

/* If we've gotten here, we could not find the pixel to write to. */
throw new Exception("Could not find the pixel we were suppose to write to.");
}

/* To handle reallocating the surfaces, lest they become lost or disposed. */
internal static void sLoadResources()
{
for (int TheLoop = 0; TheLoop < MyCylinders.Count; TheLoop++)
MyCylinders[TheLoop].sLoad();
}
internal static void sUnloadResources()
{
for (int TheLoop = 0; TheLoop < MyCylinders.Count; TheLoop++)
MyCylinders[TheLoop].sUnload();
}
internal static void sDisposeTexture(cFrostTex TheTexture)
{
/* All of the segments that correspond to this texture become loose fragments! */
for (int TheLoop = 0; TheLoop < TheTexture.MyComposition.Length; TheLoop++)
MyFragments.Add(TheTexture.MyComposition[TheLoop]);
}

/* To handling applying the changes made to textures in cylinders. */
internal static void sRefreshCylinders(aVRAMSlot[] TheBands)
{
for (int TheLoop = 0; TheLoop < TheBands.Length; TheLoop++)
{
aColor[] TheCopiedPixels = new aColor[TheBands[TheLoop].MyLength];
Array.Copy(TheBands[TheLoop].MyTexture.MyPixels, TheBands[TheLoop].MyIndex, TheCopiedPixels,0, TheBands[TheLoop].MyLength);
cGL.glBindTexture(cGL.GL_TEXTURE_1D, TheBands[TheLoop].MyTexture.MyTextureID);
cGL.glTexSubImage1D(cGL.GL_TEXTURE_1D, 0, TheBands[TheLoop].MyIndex, TheBands[TheLoop].MyLength,
cGL.GL_RGBA, cGL.GL_UNSIGNED_BYTE, TheCopiedPixels);
}
}

internal static void sOptimize()
{
/* There was a barber and his wife... */
throw new Exception("sOptimize() not implemented yet.");
}
}
}



... oh well, it was fun. And I learned a valuable lesson about optimistically adhering to advice given by those whose gender is otherwise disputed.

[Edited by - Thevenin on February 20, 2008 1:13:36 PM]

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      #shader vertex #version 330 core layout(location = 0) in vec4 aPos; layout(location = 1) in vec2 aTexCoord; out vec2 t_TexCoord; uniform mat4 u_MVP; void main() { gl_Position = u_MVP * aPos; t_TexCoord = aTexCoord; } #shader fragment #version 330 core out vec4 aColor; in vec2 t_TexCoord; uniform sampler2D u_Texture; void main() { aColor = texture(u_Texture, t_TexCoord); } Also i'm pretty sure that every time i'm hitting the up, down, left and right arrows on the keyboard, i'm changing the model Matrix of the Player and not the others.
       
      Window Class:
      #include "Window.h" #include <GL/glew.h> #include <GLFW/glfw3.h> #include "Error.h" #include "Renderer.h" #include "Scene.h" #include "Input.h" //Global Variables. int screen_width, screen_height; //On Window Resize. void OnWindowResize(GLFWwindow *window, int width, int height); //Implementation Structure. struct Window::Implementation { //GLFW Window. GLFWwindow *GLFW_window; //Renderer. Renderer *renderer; //Delta Time. double delta_time; //Frames Per Second. int fps; //Scene. Scene *scnene; //Input. Input *input; //Deconstructor. ~Implementation(); }; //Window Constructor. Window::Window(std::string title, int width, int height) { //Initializing width and height. screen_width = width; screen_height = height; //Create Pointer To Implementation. m_Impl = new Implementation(); //Try initializing GLFW. if (!glfwInit()) { std::cout << "GLFW could not be initialized!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); exit(-1); } //Setting up OpenGL Version 3.3 Core Profile. glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3); glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3); glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE); /* Create a windowed mode window and its OpenGL context */ m_Impl->GLFW_window = glfwCreateWindow(width, height, title.c_str(), NULL, NULL); if (!m_Impl->GLFW_window) { std::cout << "GLFW could not create a window!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); glfwTerminate(); exit(-1); } /* Make the window's context current */ glfwMakeContextCurrent(m_Impl->GLFW_window); //Initialize GLEW. if(glewInit() != GLEW_OK) { std::cout << "GLEW could not be initialized!" << std::endl; std::cout << "Press ENTER to exit..." << std::endl; std::cin.get(); glfwTerminate(); exit(-1); } //Enabling Blending. GLCall(glEnable(GL_BLEND)); GLCall(glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA)); //Setting the ViewPort. GLCall(glViewport(0, 0, width, height)); //**********Initializing Implementation**********// m_Impl->renderer = new Renderer(); m_Impl->delta_time = 0.0; m_Impl->fps = 0; m_Impl->input = new Input(this); //**********Initializing Implementation**********// //Set Frame Buffer Size Callback. glfwSetFramebufferSizeCallback(m_Impl->GLFW_window, OnWindowResize); } //Window Deconstructor. Window::~Window() { delete m_Impl; } //Window Main Loop. void Window::MainLoop() { //Time Variables. double start_time = 0, end_time = 0, old_time = 0, total_time = 0; //Frames Counter. int frames = 0; /* Loop until the user closes the window */ while (!glfwWindowShouldClose(m_Impl->GLFW_window)) { old_time = start_time; //Total time of previous frame. start_time = glfwGetTime(); //Current frame start time. //Calculate the Delta Time. m_Impl->delta_time = start_time - old_time; //Get Frames Per Second. if (total_time >= 1) { m_Impl->fps = frames; total_time = 0; frames = 0; } //Clearing The Screen. m_Impl->renderer->Clear(0, 0, 0); //Render The Scene. if (m_Impl->scnene != NULL) m_Impl->scnene->Render(this); //Updating the Screen. m_Impl->renderer->Update(m_Impl->GLFW_window); //Increasing frames counter. frames++; //End Time. end_time = glfwGetTime(); //Total time after the frame completed. total_time += end_time - start_time; } //Terminate GLFW. glfwTerminate(); } //Load Scene. void Window::LoadScene(Scene * scene) { //Set the scene. m_Impl->scnene = scene; } //Get Delta Time. double Window::GetDeltaTime() { return m_Impl->delta_time; } //Get FPS. int Window::GetFPS() { return m_Impl->fps; } //Get Width. int Window::GetWidth() { return screen_width; } //Get Height. int Window::GetHeight() { return screen_height; } //Get Input. Input * Window::GetInput() { return m_Impl->input; } Renderer * Window::GetRenderer() { return m_Impl->renderer; } GLFWwindow * Window::GetGLFWindow() { return m_Impl->GLFW_window; } //Implementation Deconstructor. Window::Implementation::~Implementation() { delete renderer; delete input; } //OnWindowResize void OnWindowResize(GLFWwindow *window, int width, int height) { screen_width = width; screen_height = height; //Updating the ViewPort. GLCall(glViewport(0, 0, width, height)); }  
      Brain Class
      #include "Brain.h" #include "Sprite.h" #include "Window.h" struct Brain::Implementation { //Just A Flag. bool started; //Window Pointer. Window *window; //Sprite Pointer. Sprite *sprite; }; Brain::Brain(Window *window, Sprite *sprite) { //Create Pointer To Implementation. m_Impl = new Implementation(); //Initialize Implementation. m_Impl->started = true; m_Impl->window = window; m_Impl->sprite = sprite; } Brain::~Brain() { //Delete Pointer To Implementation. delete m_Impl; } void Brain::Start() { } void Brain::Update() { } Window * Brain::GetWindow() { return m_Impl->window; } Sprite * Brain::GetSprite() { return m_Impl->sprite; } bool Brain::GetStart() { return m_Impl->started; } void Brain::SetStart(bool value) { m_Impl->started = value; } Script Class (Its a Brain Subclass!!!)
      #include "Script.h" Script::Script(Window *window, Sprite *sprite) : Brain(window, sprite) { } Script::~Script() { } void Script::Start() { std::cout << "Game Started!" << std::endl; } void Script::Update() { Input *input = this->GetWindow()->GetInput(); Sprite *sp = this->GetSprite(); //Move this sprite. this->GetSprite()->Move(200 * this->GetWindow()->GetDeltaTime(), input->GetKeyDown("left"), input->GetKeyDown("right"), input->GetKeyDown("up"), input->GetKeyDown("down")); std::cout << sp->GetTag().c_str() << ".x = " << sp->GetPos()->x << ", " << sp->GetTag().c_str() << ".y = " << sp->GetPos()->y << std::endl; }  
      Main:
      #include "SpaceShooterEngine.h" #include "Script.h" int main() { Window w("title", 600,600); Scene *scene = new Scene(); Sprite *player = new Sprite("Resources/Images/player.png", "Player", 100,100); Sprite *other = new Sprite("Resources/Images/cherno.png", "Other", 400, 100); Sprite *other2 = new Sprite("Resources/Images/cherno.png", "Other", 300, 400); Brain *brain = new Script(&w, player); player->AddBrain(brain); scene->AddSprite(player); scene->AddSprite(other); scene->AddSprite(other2); w.LoadScene(scene); w.MainLoop(); return 0; }  
       
      I literally can't find what is wrong. If you need more code, ask me to post it. I will also attach all the source files.
      Brain.cpp
      Error.cpp
      IndexBuffer.cpp
      Input.cpp
      Renderer.cpp
      Scene.cpp
      Shader.cpp
      Sprite.cpp
      Texture.cpp
      VertexArray.cpp
      VertexBuffer.cpp
      VertexBufferLayout.cpp
      Window.cpp
      Brain.h
      Error.h
      IndexBuffer.h
      Input.h
      Renderer.h
      Scene.h
      Shader.h
      SpaceShooterEngine.h
      Sprite.h
      Texture.h
      VertexArray.h
      VertexBuffer.h
      VertexBufferLayout.h
      Window.h
    • By Cristian Decu
      Hello fellow programmers,
      For a couple of days now i've decided to build my own planet renderer just to see how floating point precision issues
      can be tackled. As you probably imagine, i've quickly faced FPP issues when trying to render absurdly large planets.
       
      I have used the classical quadtree LOD approach;
      I've generated my grids with 33 vertices, (x: -1 to 1, y: -1 to 1, z = 0).
      Each grid is managed by a TerrainNode class that, depending on the side it represents (top, bottom, left right, front, back),
      creates a special rotation-translation matrix that moves and rotates the grid away from the origin so that when i finally
      normalize all the vertices on my vertex shader i can get a perfect sphere.
      T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, 1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(180.0), glm::dvec3(1.0, 0.0, 0.0)); sides[0] = new TerrainNode(1.0, radius, T * R, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_FRONT)); T = glm::translate(glm::dmat4(1.0), glm::dvec3(0.0, 0.0, -1.0)); R = glm::rotate(glm::dmat4(1.0), glm::radians(0.0), glm::dvec3(1.0, 0.0, 0.0)); sides[1] = new TerrainNode(1.0, radius, R * T, glm::dvec2(0.0, 0.0), new TerrainTile(1.0, SIDE_BACK)); // So on and so forth for the rest of the sides As you can see, for the front side grid, i rotate it 180 degrees to make it face the camera and push it towards the eye;
      the back side is handled almost the same way only that i don't need to rotate it but simply push it away from the eye.
      The same technique is applied for the rest of the faces (obviously, with the proper rotations / translations).
      The matrix that result from the multiplication of R and T (in that particular order) is send to my vertex shader as `r_Grid'.
      // spherify vec3 V = normalize((r_Grid * vec4(r_Vertex, 1.0)).xyz); gl_Position = r_ModelViewProjection * vec4(V, 1.0); The `r_ModelViewProjection' matrix is generated on the CPU in this manner.
      // No the most efficient way, but it works. glm::dmat4 Camera::getMatrix() { // Create the view matrix // Roll, Yaw and Pitch are all quaternions. glm::dmat4 View = glm::toMat4(Roll) * glm::toMat4(Pitch) * glm::toMat4(Yaw); // The model matrix is generated by translating in the oposite direction of the camera. glm::dmat4 Model = glm::translate(glm::dmat4(1.0), -Position); // Projection = glm::perspective(fovY, aspect, zNear, zFar); // zNear = 0.1, zFar = 1.0995116e12 return Projection * View * Model; } I managed to get rid of z-fighting by using a technique called Logarithmic Depth Buffer described in this article; it works amazingly well, no z-fighting at all, at least not visible.
      Each frame i'm rendering each node by sending the generated matrices this way.
      // set the r_ModelViewProjection uniform // Sneak in the mRadiusMatrix which is a matrix that contains the radius of my planet. Shader::setUniform(0, Camera::getInstance()->getMatrix() * mRadiusMatrix); // set the r_Grid matrix uniform i created earlier. Shader::setUniform(1, r_Grid); grid->render(); My planet's radius is around 6400000.0 units, absurdly large, but that's what i really want to achieve;
      Everything works well, the node's split and merge as you'd expect, however whenever i get close to the surface
      of the planet the rounding errors start to kick in giving me that lovely stairs effect.
      I've read that if i could render each grid relative to the camera i could get better precision on the surface, effectively
      getting rid of those rounding errors.
       
      My question is how can i achieve this relative to camera rendering in my scenario here?
      I know that i have to do most of the work on the CPU with double, and that's exactly what i'm doing.
      I only use double on the CPU side where i also do most of the matrix multiplications.
      As you can see from my vertex shader i only do the usual r_ModelViewProjection * (some vertex coords).
       
      Thank you for your suggestions!
       
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