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• By tj8146
I am using immediate mode for OpenGL and I am creating a 2D top down car game. I am trying to configure my game loop in order to get my car-like physics working on a square shape. I have working code but it is not doing as I want it to. I am not sure as to whether it is my game loop that is incorrect or my code for the square is incorrect, or maybe both! Could someone help because I have been trying to work this out for over a day now
I have attached my .cpp file if you wish to run it for yourself..
WinMain code:
/******************* WIN32 FUNCTIONS ***************************/ int WINAPI WinMain( HINSTANCE hInstance, // Instance HINSTANCE hPrevInstance, // Previous Instance LPSTR lpCmdLine, // Command Line Parameters int nCmdShow) // Window Show State { MSG msg; // Windows Message Structure bool done=false; // Bool Variable To Exit Loop Car car; car.x = 220; car.y = 140; car.dx = 0; car.dy = 0; car.ang = 0; AllocConsole(); FILE *stream; freopen_s(&stream, "CONOUT$", "w", stdout); // Create Our OpenGL Window if (!CreateGLWindow("OpenGL Win32 Example",screenWidth,screenHeight)) { return 0; // Quit If Window Was Not Created } while(!done) // Loop That Runs While done=FALSE { if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting? { if (msg.message==WM_QUIT) // Have We Received A Quit Message? { done=true; // If So done=TRUE break; } else // If Not, Deal With Window Messages { TranslateMessage(&msg); // Translate The Message DispatchMessage(&msg); // Dispatch The Message } } else // If There Are No Messages { if(keys[VK_ESCAPE]) done = true; void processKeys(Car& car); //process keyboard while (game_is_running) { loops = 0; while (GetTickCount() > next_game_tick && loops < MAX_FRAMESKIP) { update(car); // update variables next_game_tick += SKIP_TICKS; loops++; } display(car); // Draw The Scene SwapBuffers(hDC); // Swap Buffers (Double Buffering) } } } // Shutdown KillGLWindow(); // Kill The Window return (int)(msg.wParam); // Exit The Program } //WIN32 Processes function - useful for responding to user inputs or other events. LRESULT CALLBACK WndProc( HWND hWnd, // Handle For This Window UINT uMsg, // Message For This Window WPARAM wParam, // Additional Message Information LPARAM lParam) // Additional Message Information { switch (uMsg) // Check For Windows Messages { case WM_CLOSE: // Did We Receive A Close Message? { PostQuitMessage(0); // Send A Quit Message return 0; // Jump Back } break; case WM_SIZE: // Resize The OpenGL Window { reshape(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height return 0; // Jump Back } break; case WM_LBUTTONDOWN: { mouse_x = LOWORD(lParam); mouse_y = screenHeight - HIWORD(lParam); LeftPressed = true; } break; case WM_LBUTTONUP: { LeftPressed = false; } break; case WM_MOUSEMOVE: { mouse_x = LOWORD(lParam); mouse_y = screenHeight - HIWORD(lParam); } break; case WM_KEYDOWN: // Is A Key Being Held Down? { keys[wParam] = true; // If So, Mark It As TRUE return 0; // Jump Back } break; case WM_KEYUP: // Has A Key Been Released? { keys[wParam] = false; // If So, Mark It As FALSE return 0; // Jump Back } break; } // Pass All Unhandled Messages To DefWindowProc return DefWindowProc(hWnd,uMsg,wParam,lParam); } C++ and OpenGL code: int mouse_x=0, mouse_y=0; bool LeftPressed = false; int screenWidth=1080, screenHeight=960; bool keys[256]; float radiansFromDegrees(float deg) { return deg * (M_PI / 180.0f); } float degreesFromRadians(float rad) { return rad / (M_PI / 180.0f); } bool game_is_running = true; const int TICKS_PER_SECOND = 50; const int SKIP_TICKS = 1000 / TICKS_PER_SECOND; const int MAX_FRAMESKIP = 10; DWORD next_game_tick = GetTickCount(); int loops; typedef struct { float x, y; float dx, dy; float ang; }Car; //OPENGL FUNCTION PROTOTYPES void display(const Car& car); //called in winmain to draw everything to the screen void reshape(int width, int height); //called when the window is resized void init(); //called in winmain when the program starts. void processKeys(Car& car); //called in winmain to process keyboard input void update(Car& car); //called in winmain to update variables /************* START OF OPENGL FUNCTIONS ****************/ void display(const Car& car) { const float w = 50.0f; const float h = 50.0f; glClear(GL_COLOR_BUFFER_BIT); glLoadIdentity(); glTranslatef(100, 100, 0); glBegin(GL_POLYGON); glVertex2f(car.x, car.y); glVertex2f(car.x + w, car.y); glVertex2f(car.x + w, car.y + h); glVertex2f(car.x, car.y + h); glEnd(); glFlush(); } void reshape(int width, int height) // Resize the OpenGL window { screenWidth = width; screenHeight = height; // to ensure the mouse coordinates match // we will use these values to set the coordinate system glViewport(0, 0, width, height); // Reset the current viewport glMatrixMode(GL_PROJECTION); // select the projection matrix stack glLoadIdentity(); // reset the top of the projection matrix to an identity matrix gluOrtho2D(0, screenWidth, 0, screenHeight); // set the coordinate system for the window glMatrixMode(GL_MODELVIEW); // Select the modelview matrix stack glLoadIdentity(); // Reset the top of the modelview matrix to an identity matrix } void init() { glClearColor(1.0, 1.0, 0.0, 0.0); //sets the clear colour to yellow //glClear(GL_COLOR_BUFFER_BIT) in the display function //will clear the buffer to this colour. } void processKeys(Car& car) { if (keys[VK_UP]) { float cdx = sinf(radiansFromDegrees(car.ang)); float cdy = -cosf(radiansFromDegrees(car.ang)); car.dx += cdx; car.dy += cdy; } if (keys[VK_DOWN]) { float cdx = sinf(radiansFromDegrees(car.ang)); float cdy = -cosf(radiansFromDegrees(car.ang)); car.dx += -cdx; car.dy += -cdy; } if (keys[VK_LEFT]) { car.ang -= 2; } if (keys[VK_RIGHT]) { car.ang += 2; } } void update(Car& car) { car.x += car.dx*next_game_tick; } game.cpp • By tj8146 I am using immediate mode for OpenGL and I am creating a 2D top down car game. I am trying to configure my game loop in order to get my car-like physics working on a square shape. I have working code but it is not doing as I want it to. I am not sure as to whether it is my game loop that is incorrect or my code for the square is incorrect, or maybe both! Could someone help because I have been trying to work this out for over a day now I have attached my .cpp file if you wish to run it for yourself.. This is my C++ and OpenGL code: int mouse_x=0, mouse_y=0; bool LeftPressed = false; int screenWidth=1080, screenHeight=960; bool keys[256]; float radiansFromDegrees(float deg) { return deg * (M_PI / 180.0f); } float degreesFromRadians(float rad) { return rad / (M_PI / 180.0f); } bool game_is_running = true; const int TICKS_PER_SECOND = 50; const int SKIP_TICKS = 1000 / TICKS_PER_SECOND; const int MAX_FRAMESKIP = 10; DWORD next_game_tick = GetTickCount(); int loops; typedef struct { float x, y; float dx, dy; float ang; }Car; //OPENGL FUNCTION PROTOTYPES void display(const Car& car); //called in winmain to draw everything to the screen void reshape(int width, int height); //called when the window is resized void init(); //called in winmain when the program starts. void processKeys(Car& car); //called in winmain to process keyboard input void update(Car& car); //called in winmain to update variables /************* START OF OPENGL FUNCTIONS ****************/ void display(const Car& car) { const float w = 50.0f; const float h = 50.0f; glClear(GL_COLOR_BUFFER_BIT); glLoadIdentity(); glTranslatef(100, 100, 0); glBegin(GL_POLYGON); glVertex2f(car.x, car.y); glVertex2f(car.x + w, car.y); glVertex2f(car.x + w, car.y + h); glVertex2f(car.x, car.y + h); glEnd(); glFlush(); } void reshape(int width, int height) // Resize the OpenGL window { screenWidth = width; screenHeight = height; // to ensure the mouse coordinates match // we will use these values to set the coordinate system glViewport(0, 0, width, height); // Reset the current viewport glMatrixMode(GL_PROJECTION); // select the projection matrix stack glLoadIdentity(); // reset the top of the projection matrix to an identity matrix gluOrtho2D(0, screenWidth, 0, screenHeight); // set the coordinate system for the window glMatrixMode(GL_MODELVIEW); // Select the modelview matrix stack glLoadIdentity(); // Reset the top of the modelview matrix to an identity matrix } void init() { glClearColor(1.0, 1.0, 0.0, 0.0); //sets the clear colour to yellow //glClear(GL_COLOR_BUFFER_BIT) in the display function //will clear the buffer to this colour. } void processKeys(Car& car) { if (keys[VK_UP]) { float cdx = sinf(radiansFromDegrees(car.ang)); float cdy = -cosf(radiansFromDegrees(car.ang)); car.dx += cdx; car.dy += cdy; } if (keys[VK_DOWN]) { float cdx = sinf(radiansFromDegrees(car.ang)); float cdy = -cosf(radiansFromDegrees(car.ang)); car.dx += -cdx; car.dy += -cdy; } if (keys[VK_LEFT]) { car.ang -= 2; } if (keys[VK_RIGHT]) { car.ang += 2; } } void update(Car& car) { car.x += car.dx*next_game_tick; } My WinMain code: /******************* WIN32 FUNCTIONS ***************************/ int WINAPI WinMain( HINSTANCE hInstance, // Instance HINSTANCE hPrevInstance, // Previous Instance LPSTR lpCmdLine, // Command Line Parameters int nCmdShow) // Window Show State { MSG msg; // Windows Message Structure bool done=false; // Bool Variable To Exit Loop Car car; car.x = 220; car.y = 140; car.dx = 0; car.dy = 0; car.ang = 0; AllocConsole(); FILE *stream; freopen_s(&stream, "CONOUT$", "w", stdout); // Create Our OpenGL Window if (!CreateGLWindow("OpenGL Win32 Example",screenWidth,screenHeight)) { return 0; // Quit If Window Was Not Created } while(!done) // Loop That Runs While done=FALSE { if (PeekMessage(&msg,NULL,0,0,PM_REMOVE)) // Is There A Message Waiting? { if (msg.message==WM_QUIT) // Have We Received A Quit Message? { done=true; // If So done=TRUE break; } else // If Not, Deal With Window Messages { TranslateMessage(&msg); // Translate The Message DispatchMessage(&msg); // Dispatch The Message } } else // If There Are No Messages { if(keys[VK_ESCAPE]) done = true; void processKeys(Car& car); //process keyboard while (game_is_running) { loops = 0; while (GetTickCount() > next_game_tick && loops < MAX_FRAMESKIP) { update(car); // update variables next_game_tick += SKIP_TICKS; loops++; } display(car); // Draw The Scene SwapBuffers(hDC); // Swap Buffers (Double Buffering) } } } // Shutdown KillGLWindow(); // Kill The Window return (int)(msg.wParam); // Exit The Program } //WIN32 Processes function - useful for responding to user inputs or other events. LRESULT CALLBACK WndProc( HWND hWnd, // Handle For This Window UINT uMsg, // Message For This Window WPARAM wParam, // Additional Message Information LPARAM lParam) // Additional Message Information { switch (uMsg) // Check For Windows Messages { case WM_CLOSE: // Did We Receive A Close Message? { PostQuitMessage(0); // Send A Quit Message return 0; // Jump Back } break; case WM_SIZE: // Resize The OpenGL Window { reshape(LOWORD(lParam),HIWORD(lParam)); // LoWord=Width, HiWord=Height return 0; // Jump Back } break; case WM_LBUTTONDOWN: { mouse_x = LOWORD(lParam); mouse_y = screenHeight - HIWORD(lParam); LeftPressed = true; } break; case WM_LBUTTONUP: { LeftPressed = false; } break; case WM_MOUSEMOVE: { mouse_x = LOWORD(lParam); mouse_y = screenHeight - HIWORD(lParam); } break; case WM_KEYDOWN: // Is A Key Being Held Down? { keys[wParam] = true; // If So, Mark It As TRUE return 0; // Jump Back } break; case WM_KEYUP: // Has A Key Been Released? { keys[wParam] = false; // If So, Mark It As FALSE return 0; // Jump Back } break; } // Pass All Unhandled Messages To DefWindowProc return DefWindowProc(hWnd,uMsg,wParam,lParam); }
game.cpp
• By lxjk
Hi guys,
There are many ways to do light culling in tile-based shading. I've been playing with this idea for a while, and just want to throw it out there.
Because tile frustums are general small compared to light radius, I tried using cone test to reduce false positives introduced by commonly used sphere-frustum test.
On top of that, I use distance to camera rather than depth for near/far test (aka. sliced by spheres).
This method can be naturally extended to clustered light culling as well.
The following image shows the general ideas

Performance-wise I get around 15% improvement over sphere-frustum test. You can also see how a single light performs as the following: from left to right (1) standard rendering of a point light; then tiles passed the test of (2) sphere-frustum test; (3) cone test; (4) spherical-sliced cone test

I put the details in my blog post (https://lxjk.github.io/2018/03/25/Improve-Tile-based-Light-Culling-with-Spherical-sliced-Cone.html), GLSL source code included!

Eric

• Good evening everyone!

I was wondering if there is something equivalent of  GL_NV_blend_equation_advanced for AMD?
Basically I'm trying to find more compatible version of it.

Thank you!

• Hello guys,

How do I know? Why does wavefront not show for me?
I already checked I have non errors yet.

And my download (mega.nz) should it is original but I tried no success...
- Add blend source and png file here I have tried tried,.....

PS: Why is our community not active? I wait very longer. Stop to lie me!
Thanks !

# OpenGL Looking for heightmap (not landscape) optimization

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Hi,

The easiest way for you to get some more speed would be to use vertex buffer objects (if you have it implemented with vertex arrays then you are pretty much there).
However, I can't think of many reasons for rendering such a big mesh unless you are making some sort of level editing/creation application. In which case, surely you don't need to update it that often.

Heightmap lod algorithms have their advantages and disadvantages depending on the situation, so if you do want to implement lod you should have a look at roam, clod and geomipmapping (among others [smile]) and see which one would best suit your needs.

Regards,
ViLiO

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Yes I definitely should give vertex buffer objects a try. I'm still in the progress of learning how they work :)

But I'm confused about what is written about optimizations. At several places I read that ROAM is not very useful anymore today. With nowadays cards, it's told to be more effective to let the GPU handle the additional vertices than keeping the CPU busy with ROAM calculations. I wonder if this would still apply to my case (1 million vertices sounds very high to render them all to me, and maybe I need to go even higher)

I wonder if I should concentrate on reducing the tri/quad count somehow (ROAM) or on increasing processing speed (e.g. by using vertex buffer objects).

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Hi again,

I must admit I am puzzled by your need to render so much data all at the same time [smile]. You say the whole heightmap is visible most of the time ...but in which way do you view it? If you are looking across the mesh from a low camera angle then you were benefit greatly from some sort of lod (probably geomipmapping) and of course you could make use of occlusion. Lod would allow you to greatly reduce the vertex count of the parts of the heightmap that are far from the camera. Occlusion has obvious benefits [grin]
It would be a good idea to split your heightmap up into 65x65 chunks anyway, as having a vertex buffer object that is too large causes slowdown (65x65 vertices is good for most hardware but you can of course experiment). The whole heightmap can also be tri-stripped quite easily.

Best of luck,
ViLiO

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It's hard to explain what the project does that I'm working on. The user can see an object from above and modify its surface at runtime. It looks a little like you would write letters with your finger into the sand. The user usually looks at the working object from above, but he should be able to zoom in a lot without loosing too much details. So I created a huge height map which has a high enough resolution and used it to present my objects surface. Unfortunately my first attempt to draw a quad onto each 4 adjacent heights to form a surface worked first, but (of course) became extremely slow now that the heightmap became so huge.

I don't necessarily need to render all the data of the heightmap. If the user has zoomed out, there's no need to render every vertex, because they can't be distinguished anyway :). It's just that I need to store the data in such a high resolution so that the user would be able to zoom in and see details.

LOD, ROAM, Geomipmapping, I read a lot about all the methods and I think I basically understand them all, but where I'm getting more and more confused is that all articles and papers I read are related to terrain rendering (which is somewhat different to what I do, e.g. in my case the heights aren't fixed and geomipmaps can't be precalculated, and the user usually sees the whole heightmap area, not only a small part of it (which would make frustum culling useless, at least unless the user doesn't zoom in a lot)

I was also thinking about partitioning the heightmap into several smaller pieces by using a quadtree and somehow using some of the tree nodes to generate geomipmaps in realtime, but I'm not sure if that wouldn't drastically increase the memory usage (e.g.for linking so many tree nodes)

In some articles they mentioned that nowadays it's often faster/better to let the GPU handle some additional polygons than wasting CPU cycles for removing invisible polygons. E.g. in my case a user would watch the whole object 90% of his time, which makes frustum culling useless. Even if he zooms in, I'd say that at a maximum he still sees 50% of the object. That doesn't sound like frustum culling would make sense in my case - but I'm just missing experience when it comes to this, and so I'm getting confused more and more :-)

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Well, the last thing I can suggest is parallax mapping.
I suspect I am about to go way over my head here considering I have never implemented parallax [grin].

From my limited knowledge, parallax is similar to bump mapping, only it gives the appearance of full displacement mapping (aka heightmap). This would mean you would only need to change texture data and not move individual vertices, so you could have a single quad with a 1024x1024 parallax map. The downside is that it is an image based technique and doesn't actually modify vertices, so if viewed from acute angles, you can see that the quad would actuall be flat.

Hopefully though i've given you some food for thought [smile]

All the best,
ViLiO

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Well I'm sure vertex buffer objects would help. They might not work for the same reason as display lists though. Try chopping your mesh into 4 or more chunks, and see if it can handle it then.

Not sure how much this will help, but it's something to try. When the user can see the whole thing, you obviously don't need that much detail (you probably have a near 1 to 1 ratio of poly's and pixels). Now your not the usual fps player that needs detail close up and not further away, your a high up observer. So, I suggest just dropping 3 quarters of the polys. Rather than making a mesh that uses every vertex, skip every second one. So,
.---.---.|   |   |.---.---.|   |   |.---.---.becomes.---.---.|       |.   .   .|       |.---.---.

You'll need the detail when you zoom in though, but hopefully then you can cull some of your mesh. Rather than doing it yourself, I'd recommend the vertex culling extension.

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I'm doing something similar and I'm doing this:

1) I create a mesh which is really simple and optimized then I save it into RAM
2) Move this mesh (usually 1024x1024) to the video card using VBO.
3) Load a heightmap and the corresponding normal map.
4) Displace the mesh in the vertex shader using texture fetch.
5) Do per-pixel lights with the pre-calculated normal maps
6) Done.

I normally get around 30-40 fps in a 6800gt. I'm sure you can get a better fps if you:
a) Divide the mesh into smaller chunks for optimization.
b) Cull the unnecessary polygons when zomming.

Hope that help.
:)

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From your description, it seems like the heightmap is mostly fixed. The exception is that every frame a relatively small area is changed. Assuming that is true, then a LOD terrain algorithm (particularly geomipmapping) is appropriate.

You wrote, "in my case the heights aren't fixed and geomipmaps can't be precalculated". That is not true.

The reason I suggest geomipmapping is how it implements LOD. In geomipmapping, LOD is achieved through a predetermined method of vertex selection and is independent of the data (except for determining the LOD thresholds). So when the heightmap changes, all you have to do is determine the new LOD thresholds. You could even skip that if you don't mind some popping.

Normally for rendering a terrain, I recommend "Chunked LOD", but it requires some preprocessing so it is probably not appropriate in this case.