Thanks guys!
@Erik Rufelt An example would be great! :)
Render only the Depth Buffer
What OS/compiler are you on?
This is for Windows, should compile in VC++ in an empty Windows project.
This is for Windows, should compile in VC++ in an empty Windows project.
#include <windows.h>#include <gl/gl.h>#include <gl/glu.h>#include <gl/glext.h>#pragma comment (lib, "opengl32.lib")#pragma comment (lib, "glu32.lib")LRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam);// Mainint WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nCmdShow) { // Register windowclass WNDCLASSEX wc; ZeroMemory(&wc, sizeof(wc)); wc.cbSize = sizeof(wc); wc.lpszClassName = TEXT("MyClass"); wc.hInstance = hInstance; wc.lpfnWndProc = WndProc; wc.hCursor = LoadCursor(NULL, IDC_ARROW); wc.hIcon = LoadIcon(NULL, IDI_APPLICATION); RegisterClassEx(&wc); // Create window HWND hWnd = CreateWindowEx( 0, wc.lpszClassName, TEXT("OpenGL Depth Display"), WS_OVERLAPPEDWINDOW, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, CW_USEDEFAULT, NULL, NULL, hInstance, NULL ); // Get DC HDC hDC = GetDC(hWnd); // Pixelformat PIXELFORMATDESCRIPTOR pfd; ZeroMemory(&pfd, sizeof(pfd)); pfd.nSize = sizeof(pfd); pfd.nVersion = 1; pfd.dwFlags = PFD_DRAW_TO_WINDOW | PFD_SUPPORT_OPENGL | PFD_DOUBLEBUFFER | PFD_SUPPORT_COMPOSITION; pfd.iPixelType = PFD_TYPE_RGBA; pfd.cColorBits = 32; pfd.cDepthBits = 24; pfd.cStencilBits = 8; int pf = ChoosePixelFormat(hDC, &pfd); SetPixelFormat(hDC, pf, &pfd); // OpenGL context HGLRC hGLRC = wglCreateContext(hDC); wglMakeCurrent(hDC, hGLRC); // Create a 1D texture fading from black to white GLuint fadeTextureId; glGenTextures(1, &fadeTextureId); glBindTexture(GL_TEXTURE_1D, fadeTextureId); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MAG_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_MIN_FILTER, GL_LINEAR); glTexParameteri(GL_TEXTURE_1D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); unsigned int fadeTextureData[256]; for(int i=0;i<256;++i) fadeTextureData = 0xff000000 | (i << 16) | (i << 8) | i; glTexImage1D(GL_TEXTURE_1D, 0, GL_RGBA, 256, 0, GL_RGBA, GL_UNSIGNED_BYTE, fadeTextureData); // Main loop ShowWindow(hWnd, nCmdShow); while(true) { MSG msg; if(PeekMessage(&msg, NULL, 0, 0, PM_REMOVE) != 0) { if(msg.message == WM_QUIT) break; else { TranslateMessage(&msg); DispatchMessage(&msg); } } else { // Clear glClearColor(0.0f, 0.0f, 0.0f, 0.0f); glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT); glEnable(GL_DEPTH_TEST); // Reset modelview matrix glMatrixMode(GL_MODELVIEW); glLoadIdentity(); // Set texture coord generation plane based on Z // Takes current matrix into account, so do it now with identity set // -1/100 is because the far-plane is at 100, use the actual far-plane value GLfloat splane[4] = {0.0f, 0.0f, -1.0f/100.0f, 0.0f}; glTexGenfv(GL_S, GL_EYE_PLANE, splane); // Enable texture-coord generation. The texture S coordinate will be set to // the same relative position in [0, 1] as the Z-value is in [0, far-plane] // Since the 1D-texture fades from black to white, colors will fade from black // to white based on distance when using this texture with tex-coord generation glEnable(GL_TEXTURE_1D); glEnable(GL_TEXTURE_GEN_S); glTexGeni(GL_S, GL_TEXTURE_GEN_MODE, GL_EYE_LINEAR); // Camera glRotatef(20.0f, 1.0f, 0.0f, 0.0f); glRotatef(-20.0f, 0.0f, 1.0f, 0.0f); glTranslatef(-10.0f, -10.0f, -20.0f); // Draw test cubes glEnable(GL_CULL_FACE); glCullFace(GL_BACK); const GLfloat cubeVertices[] = { -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, 1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, -1.0f, 1.0f, -1.0f, -1.0f, 1.0f, 1.0f, -1.0f, -1.0f, 1.0f, -1.0f, }; const int cubeIndices[] = {0, 1, 3, 2, 6, 1, 5, 0, 4, 3, 7, 6, 4, 5}; glTranslatef(0.0f, 0.0f, -80.0f); for(int cubeIndex=0;cubeIndex<20;++cubeIndex) { glTranslatef(0.0f, 0.0f, 5.0f); glBegin(GL_TRIANGLE_STRIP); for(int i=0;i<14;++i) glVertex3fv(cubeVertices+cubeIndices*3); glEnd(); } // Swap SwapBuffers(hDC); } } glDeleteTextures(1, &fadeTextureId); wglDeleteContext(hGLRC); UnregisterClass(wc.lpszClassName, hInstance); return 0;}// Window procedureLRESULT CALLBACK WndProc(HWND hWnd, UINT msg, WPARAM wParam, LPARAM lParam) { switch(msg) { case WM_DESTROY: PostQuitMessage(0); break; case WM_SIZE: glViewport(0, 0, LOWORD(lParam), HIWORD(lParam)); glMatrixMode(GL_PROJECTION); glLoadIdentity(); gluPerspective(45.0, (GLdouble)LOWORD(lParam) / HIWORD(lParam), 1.0, 100.0); break; } return DefWindowProc(hWnd, msg, wParam, lParam);}
I'm having the same issue.
Doing
results in a solid gray teapot. It's the same color no matter how far the teapot is and you can't see any features. Here is an image:
Doing
glutSolidTeapot(4); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, 3, WIDTH, HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, 0); glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 0, 0, WIDTH, HEIGHT, 0); glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -17); //render quad with texture, etcresults in a solid gray teapot. It's the same color no matter how far the teapot is and you can't see any features. Here is an image:
Actually I just read ignifex's reply and I set the near and far clip planes from 1 and 100 to 12 and 20 respectively
code:
gluPerspective( 60.0, ratio, 12.0, 20.0 );
which resulted in this nice render:
@Jayinmn I think your problem has to do with the near and far clip planes cause you mentioned getting a gray texture. That's probably from the z buffer inaccuracies issue I had.
@Erik Rufelt Your code produced some funky results. The teapot ended up looking all striped and crazy.
code:
gluPerspective( 60.0, ratio, 12.0, 20.0 );
which resulted in this nice render:
@Jayinmn I think your problem has to do with the near and far clip planes cause you mentioned getting a gray texture. That's probably from the z buffer inaccuracies issue I had.
@Erik Rufelt Your code produced some funky results. The teapot ended up looking all striped and crazy.
Author
@nycsamurai Hey, great progress you've got there. You mind showing me your texture creation code too? I've tried your method there and still my output was still a solid gray box, I did decrease the near and the far range. Not even a slight hint of bands in the output.
I'm guessing the texture creation was the problem.
Below are my codes. I'm not sure where I've gone wrong.
My resulting scene.
If I changed GL_DEPTH_COMPONENT in glCopyTexImage2D to GL_RGB, my output will be the scene itself, which means the texture creation shouldn't be a problem. I'm not sure though.
I'm using Glut by the way. Could it be some buffers that I didn't enable that causes my depth not showing? I did include this line.
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH | GLUT_ACCUM | GLUT_MULTISAMPLE | GLUT_STENCIL);
I'm guessing the texture creation was the problem.
Below are my codes. I'm not sure where I've gone wrong.
//This is my texture creation part.
GLuint texid;
GLubyte *imageData=NULL;
glGenTextures(1, &texid);
glBindTexture(GL_TEXTURE_2D, texid);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 256, 256, 0,
GL_DEPTH_COMPONENT, GL_UNSIGNED_BYTE,imageData);
//The part where I drew the depth image.
//My screen resolution is 800x600.
glBindTexture(GL_TEXTURE_2D, texid);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexImage2D(GL_TEXTURE_2D, 0, 3,800, 600, 0,GL_RGB, GL_UNSIGNED_BYTE, 0);
glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 0, 0, 800, 600, 0);
My resulting scene.
If I changed GL_DEPTH_COMPONENT in glCopyTexImage2D to GL_RGB, my output will be the scene itself, which means the texture creation shouldn't be a problem. I'm not sure though.
I'm using Glut by the way. Could it be some buffers that I didn't enable that causes my depth not showing? I did include this line.
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH | GLUT_ACCUM | GLUT_MULTISAMPLE | GLUT_STENCIL);
Quote:Original post by nycsamurai
@Erik Rufelt Your code produced some funky results. The teapot ended up looking all striped and crazy.
I see, strange, works fine for me. Perhaps you have 2D texturing or lighting or some other render states enabled?
The point of that method is to draw to the color-buffer based on distance, and it doesn't actually use the depth-buffer. Therefore all render-states must be set to only have 1D texturing enabled.
It's probably better to get the texture from the depth-buffer, just found it a simple method. =)
Looks like this for me:
Here it is:
Dont' know about GLUT, I'm using SDL for my windowing with the following settings:
//set attributes
SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
flags = SDL_OPENGL | SDL_RESIZABLE;
Are you calling glClear(GL_DEPTH_BUFFER_BIT) before you draw your scene?
@Erik Rufelt Yeah I did have texturing enabled, sorry, disregard what I said about it.
//creation:GLuint texture[2];glGenTextures(2, texture);//here is my draw functionstatic void draw_screen(float time_elapsed){ //clear screen glClear( GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT ); //select modelview matrix glMatrixMode( GL_MODELVIEW ); glLoadIdentity(); glTranslatef(0.0, 0.0, -17); glColor4f(1.0, 0.0, 1.0, 1.0); glutSolidTeapot(4); glBindTexture(GL_TEXTURE_2D, texture[1]); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MIN_FILTER,GL_LINEAR); glTexParameteri(GL_TEXTURE_2D,GL_TEXTURE_MAG_FILTER,GL_LINEAR); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE); glTexParameterf(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE); glTexImage2D(GL_TEXTURE_2D, 0, 3, WIDTH, HEIGHT, 0, GL_RGB, GL_UNSIGNED_BYTE, 0); glCopyTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, 0, 0, WIDTH, HEIGHT, 0); //clear screen glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); glTranslatef(0.0, 0.0, -17); glColor4f(1.0, 1.0, 1.0, 1.0); glTexParameteri( GL_TEXTURE_2D, GL_DEPTH_TEXTURE_MODE, GL_LUMINANCE ); glBegin(GL_QUADS); glNormal3f(0.0, 0.0, 1.0); glTexCoord2f(0.0f, 0.0f); glVertex3f(-10.0f,-10.0f, 0.0f); glTexCoord2f(1.0f, 0.0f); glVertex3f( 10.0f,-10.0f, 0.0f); glTexCoord2f(1.0f, 1.0f); glVertex3f( 10.0f, 10.0f, 0.0f); glTexCoord2f(0.0f, 1.0f); glVertex3f(-10.0f, 10.0f, 0.0f); glEnd(); glFlush(); SDL_GL_SwapBuffers();}//and here is my setup code:static void setup_opengl( int width, int height ){ //load depth map if(!load_textures()) exit(2); //generate_image(); float ratio = (float) width / (float) height; //clear color glClearColor( 1.0, 1.0, 1.0, 1.0 ); glMatrixMode(GL_MODELVIEW); glLoadIdentity(); //set up viewport glViewport( 0, 0, width, height ); glEnable(GL_TEXTURE_2D); glEnable(GL_DEPTH_TEST); glPolygonMode (GL_FRONT_AND_BACK, GL_FILL); //set up projection matrix glMatrixMode( GL_PROJECTION ); glLoadIdentity( ); gluPerspective( 60.0, ratio, 12.0, 20.0 ); }Dont' know about GLUT, I'm using SDL for my windowing with the following settings:
//set attributes
SDL_GL_SetAttribute( SDL_GL_RED_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_GREEN_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_BLUE_SIZE, 5 );
SDL_GL_SetAttribute( SDL_GL_DEPTH_SIZE, 16 );
SDL_GL_SetAttribute( SDL_GL_DOUBLEBUFFER, 1 );
flags = SDL_OPENGL | SDL_RESIZABLE;
Are you calling glClear(GL_DEPTH_BUFFER_BIT) before you draw your scene?
@Erik Rufelt Yeah I did have texturing enabled, sorry, disregard what I said about it.
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