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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
    • By Fadey Duh
      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!
    • By Jens Eckervogt
      Hello guys, 
       
      Please tell me! 
      How do I know? Why does wavefront not show for me?
      I already checked I have non errors yet.
      using OpenTK; using System.Collections.Generic; using System.IO; using System.Text; namespace Tutorial_08.net.sourceskyboxer { public class WaveFrontLoader { private static List<Vector3> inPositions; private static List<Vector2> inTexcoords; private static List<Vector3> inNormals; private static List<float> positions; private static List<float> texcoords; private static List<int> indices; public static RawModel LoadObjModel(string filename, Loader loader) { inPositions = new List<Vector3>(); inTexcoords = new List<Vector2>(); inNormals = new List<Vector3>(); positions = new List<float>(); texcoords = new List<float>(); indices = new List<int>(); int nextIdx = 0; using (var reader = new StreamReader(File.Open("Contents/" + filename + ".obj", FileMode.Open), Encoding.UTF8)) { string line = reader.ReadLine(); int i = reader.Read(); while (true) { string[] currentLine = line.Split(); if (currentLine[0] == "v") { Vector3 pos = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inPositions.Add(pos); if (currentLine[1] == "t") { Vector2 tex = new Vector2(float.Parse(currentLine[1]), float.Parse(currentLine[2])); inTexcoords.Add(tex); } if (currentLine[1] == "n") { Vector3 nom = new Vector3(float.Parse(currentLine[1]), float.Parse(currentLine[2]), float.Parse(currentLine[3])); inNormals.Add(nom); } } if (currentLine[0] == "f") { Vector3 pos = inPositions[0]; positions.Add(pos.X); positions.Add(pos.Y); positions.Add(pos.Z); Vector2 tc = inTexcoords[0]; texcoords.Add(tc.X); texcoords.Add(tc.Y); indices.Add(nextIdx); ++nextIdx; } reader.Close(); return loader.loadToVAO(positions.ToArray(), texcoords.ToArray(), indices.ToArray()); } } } } } And It have tried other method but it can't show for me.  I am mad now. Because any OpenTK developers won't help me.
      Please help me how do I fix.

      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 !
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OpenGL Help with glDrawElementsInstanced

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SOLVED

 

I've been reading through the OpenGL instancing tutorial on learnopengl.com, and I'm trying to implement it using glDrawElementsInstanced, since I have Assimp doing my mesh loading. My problem is that the "floor" (see the wood-textured model in the attached pic) is drawing perfectly fine, but the positional offsets for instancing that I'm passing to OpenGL have no effect. What could be the problem? Thanks in advance! biggrin.png

 

floorVS.glsl:

#version 430
layout (location = 0) in vec3 position;
layout (location = 1) in vec3 normal;
layout (location = 2) in vec2 texCoords;
layout (location = 3) in vec3 offset; // For 3D instancing

layout (std140, binding = 0) uniform Matrices {
  mat4 projection;
  mat4 view;
};
uniform mat4 model;

out vec2 TexCoords;
out vec3 FragPos;
out vec3 Normal;

void main() {
  gl_Position = projection * view * model * vec4(position + offset, 1.0); // Add provided offset
  FragPos = vec3(model * vec4(position, 1.0f));
  Normal = mat3(transpose(inverse(model))) * normal;
  TexCoords = texCoords;
}

I have a Model class that contains numerous Mesh classes (since a complete model may contain several objects), so I need to make sure each mesh gets the offset data:

 

This function is run per mesh to separately add instancing data:

void Mesh::SetInstancing(const std::vector<glm::vec3>& instanceOffsets) {
	m_instanceOffsets = instanceOffsets;

	glGenBuffers(1, &m_instanceVBO);
	glBindBuffer(GL_ARRAY_BUFFER, m_instanceVBO);
	glBufferData(GL_ARRAY_BUFFER, sizeof(glm::vec3) * m_instanceOffsets.size(), &m_instanceOffsets.at(0), GL_STATIC_DRAW);
	glBindBuffer(GL_ARRAY_BUFFER, 0);

	// Vertex Instance offset
	glEnableVertexAttribArray(3);
	glBindBuffer(GL_ARRAY_BUFFER, m_instanceVBO);
	glVertexAttribPointer(3, 3, GL_FLOAT, GL_FALSE, 3 * sizeof(GLfloat), (GLvoid*)0);
	glBindBuffer(GL_ARRAY_BUFFER, 0);
	glVertexAttribDivisor(3, 1); // Tell OpenGL this is an instanced vertex attribute.

	glBindVertexArray(0);
}

Now to draw the mesh. The bindTexures function is irrelevant to my question (it just loops through a vector of Textures and binds them):

void Mesh::DrawInstanced(const Shader& shader) {
	
	bindTextures(shader);

	// Draw instanced mesh
	glBindVertexArray(m_vao);
	glDrawElementsInstanced(GL_TRIANGLES, m_indices.size(), GL_UNSIGNED_INT, 0, m_instanceOffsets.size());
	glBindVertexArray(0);
}

Picture:

There should be 2 floor object being rendered here (and the displayed floor should not be at the origin):

[attachment=33104:help.png]

 

Please let me know of any more clarification is needed!

Edited by htmlboss

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I may be missing something here so please disregard if I am being an idiot but are you sure you want offsets to be a vertex attribute rather than a uniform? From what I understand, your vertex code would allow you to individually move each vertex independently rather than move the whole thing at once. Is that what you are trying to achieve?

 

Could you also show the code where you setup these arrays? position/normal/texture/offsets.

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*snip*

Here is the code for the other arrays (this function is called in each Mesh's c-tor) and the Vertex struct (if it helps any). The setup for the offset attribute is separate because some models may not need to be drawn using instancing.:

void Mesh::setupMesh() {

	glGenVertexArrays(1, &m_vao);
	glGenBuffers(1, &m_vbo);
	glGenBuffers(1, &m_ebo);

	glBindVertexArray(m_vao);
	glBindBuffer(GL_ARRAY_BUFFER, m_vbo);

	glBufferData(GL_ARRAY_BUFFER, m_vertices.size() * sizeof(Vertex), &m_vertices.at(0), GL_STATIC_DRAW);

	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m_ebo);
	glBufferData(GL_ELEMENT_ARRAY_BUFFER, m_indices.size() * sizeof(GLuint), &m_indices.at(0), GL_STATIC_DRAW);

	// Vertex Attributes

	// Vertex Positions
	glEnableVertexAttribArray(0);
	glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)0);
	// Vertex Normals
	glEnableVertexAttribArray(1);
	glVertexAttribPointer(1, 3, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, Normal));
	// Vertex Texture Coords
	glEnableVertexAttribArray(2);
	glVertexAttribPointer(2, 2, GL_FLOAT, GL_FALSE, sizeof(Vertex), (GLvoid*)offsetof(Vertex, TexCoords));

	glBindVertexArray(0);
}

Vertex:

struct Vertex {
	glm::vec3 Position;
	glm::vec3 Normal;
	glm::vec2 TexCoords;
};

And yes, this technically should allow me to move each vertex individually (learnopengl.com discussed how the same mesh data is just shared to the other instance, except for an offset from the original position variable in the Vertex struct, instead of allocating a new "floor" model and wasting memory).

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At the bottom of your SetInstancing method you bind the vertex array to 0 but I don't see it being bound initially. From your other method it looks like you are binding m_vao at the start then binding it to 0 at the end of the methods. Have you perhaps just missed binding m_vao on that one particular method?

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At the bottom of your SetInstancing method you bind the vertex array to 0 but I don't see it being bound initially. From your other method it looks like you are binding m_vao at the start then binding it to 0 at the end of the methods. Have you perhaps just missed binding m_vao on that one particular method?

That fixed it! I'm still trying to wrap my head around OpenGL being STATE-DRIVEN (it doesn't help that I'm mixing object oriented C++ and procedural OpenGL, but I guess that's part of the learning process) rolleyes.gif

 

Thanks so much! biggrin.png

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At the bottom of your SetInstancing method you bind the vertex array to 0 but I don't see it being bound initially. From your other method it looks like you are binding m_vao at the start then binding it to 0 at the end of the methods. Have you perhaps just missed binding m_vao on that one particular method?

That fixed it! I'm still trying to wrap my head around OpenGL being STATE-DRIVEN (it doesn't help that I'm mixing object oriented C++ and procedural OpenGL, but I guess that's part of the learning process) rolleyes.gif

 

Thanks so much! biggrin.png

 

 

Yeah little things like this are easy to miss. I sometimes make little objects that ensure a thing is bound and unbind in the destructor similar to how lock guards work and I throw one at the start of my function. 

 

e.g.

TextureBinder(int desired)
{
   m_desired = desired;
   // get currently bound texture and store it
   m_previous = GetCurrentTexture();
   // if it's not the desired texture then bind it
   if(m_desired != m_previous)
      BindTexture(m_desireD);
}

~TextureBinder()
{
   // rebind the previous one if it was different
   if(m_desired != m_previous)
      BindTexture(m_previous);
}

// Then in a method where I am messing with that texture:
void A::DoSomething()
{
   TextureBinder binder(m_texture);
   // modify it
   // it is automatically reset to the previous when the method ends
}

That does add some overhead (resetting the value) but if you are doing it anyway then it's no worse and it does help avoid little mistakes like the one you had there.

Edited by Nanoha

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