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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 problem rendering rect and 2d texture at same time OpenGL

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Hello.

 

I am porting my game to android using SDL and NDK, and I am trying to make the game hardware accelerated with openGL.

In the game I need to draw colored rectangles and to draw an arbitrary bitmap.

void DrawRectangleGL( ScreenBuffer* buffer, Vec2 min, Vec2 max, Vec4 color )
{
GLfloat matrix[] = {
2.0f / buffer->width,  0,  0, 0,
0, 2.0f / buffer->height,  0, 0,
0, 0,                      1, 0,
  -1, -1,                     0, 1
};
 
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
glLoadIdentity();
glMultMatrixf( matrix );
 
GLfloat triangles[] = {
        min.X, min.Y,
        max.X, min.Y, 
        max.X, max.Y,
 
min.X, min.Y,
min.X, max.Y,
max.X, max.Y
    };
 
GLfloat colors[] = {
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
 
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W
};
 
    glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, triangles);
 
glEnableClientState( GL_COLOR_ARRAY );
glColorPointer( 4, GL_FLOAT, 0, colors );
 
    glDrawArrays(GL_TRIANGLES, 0, 6);
}
 
The function is written correctly and it works: I can render colored rectangles everywhere I want. (you can see the result in onlyRect.png)
 
Also, if I try to render ONLY 2d texture I get them on the screen perfectly with this function: (you can see the result in onlyTexture.png)
 

void DrawBitmap( ScreenBuffer* buffer, Bitmap* bitmap, Vec2 position, real32 alpha )
{
if( bitmap->textureMap == -1 )
{
glGenTextures(1, ( GLuint* ) &bitmap->textureMap);
}
 
glBindTexture(GL_TEXTURE_2D, bitmap->textureMap );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, bitmap->width, bitmap->height,
0, GL_BGRA_EXT, GL_UNSIGNED_BYTE, bitmap->pixels );
 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
 
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 
glEnable( GL_TEXTURE_2D );
 
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
glMatrixMode( GL_TEXTURE );
glLoadIdentity();
 
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
 
glMatrixMode( GL_PROJECTION );
glLoadIdentity(); 
 
GLfloat matrix[] = {
2.0f / buffer->width,  0,  0, 0,
0, 2.0f / buffer->height,  0, 0,
0, 0,                      1, 0,
  -1, -1,                     0, 1
};
 
glLoadIdentity();
glMultMatrixf( matrix );
 
 
Vec2 min = position;
Vec2 max = min + V2( bitmap->width, bitmap->height );
GLfloat triangles[] = {
        min.X, min.Y,
        max.X, min.Y, 
        max.X, max.Y,
 
min.X, min.Y,
        min.X, max.Y, 
        max.X, max.Y,
};
 
GLfloat textureVertices[] = {
        0.0f, 0.0f,
1.0f, 0.0f,
1.0f, 1.0f,
 
        0.0f,  0.0f,
0.0f, 1.0f,
1.0f, 1.0f
};
 
    glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, triangles);
 
glEnableClientState( GL_TEXTURE_COORD_ARRAY);
glTexCoordPointer( 2, GL_FLOAT, 0, textureVertices );
    glDrawArrays(GL_TRIANGLES, 0, 6);
}

 
The problem is that when I try render both rectangles and 2d texture at the same time, I get a very weird result, that you can see in both.png.
I've tried a couple of hours to solve the problem, without success.
Surely I am missing something stupid because it's the first time I use openGL, but searching into the web I did not find anything.
The problem Is just about the colors, because as you can see from both.png the position of the rect and the texture remains correct.
ps: I am clearing the screen to black and setting the viewport at the beginning of every frame with 
 

glViewport(0, 0, globalScreenBuffer.width, globalScreenBuffer.height );
glClearColor(0.0, 0.0, 0.0, 1.0);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

 
There is no other OpenGL code in the program, other than the initialization code obviously.
 
Thank you in advance.
Leonardo
Edited by erpeo93

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Two things that directly stand out to me are the matrix and the vertex states.


The matrix that is active at start by default is GL_MODELVIEW. So if you only call the first function, that matrix will be modified by

glLoadIdentity();
glMultMatrixf( matrix );

But the second function sets GL_PROJECTION active before it returns. So if you then call the first function again, you now modify that one. And even if you activate the GL_MODELVIEW here, the GL_PROJECTION would still hold the old value from the second function.


You also enable different VERTEX types with glEnableClientState, but never disable them.


Remember that lots of OpenGL states are global states in the current OpenGL context.
The easy way is just to disable them/set the standard value directly after use. This is not the most performance way to use OpenGL, but for a small project that should not be an issue. Edited by Osbios

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Two things that directly stand out to me are the matrix and the vertex states.


The matrix that is active at start by default is GL_MODELVIEW. So if you only call the first function, that matrix will be modified by

glLoadIdentity();
glMultMatrixf( matrix );
But the second function sets GL_PROJECTION active before it returns. So if you then call the first function again, you now modify that one. And even if you activate the GL_MODELVIEW here, the GL_PROJECTION would still hold the old value from the second function.


You also enable different VERTEX types with glEnableClientState, but never disable them.


Remember that lots of OpenGL states are global states in the current OpenGL context.
The easy way is just to disable them/set the standard value directly after use. This is not the most performance way to use OpenGL, but for a small project that should not be an issue.

 

thank you for the quick reply.

I've changed some of the code, and it is getting better: as you said I was never calling glDisableClientState, and that was a problem.

Now I have another problem: the position of both the texture and rectangle is correct, even when they are rendered togheter, but seems to me like only the alpha channel of the Rect is drawed, while the red green and blue don't exist. On the other side, texture are rendered perfectly in any situation.

 

Rect rendering:

void DrawRectangleGL( ScreenBuffer* buffer, Vec2 min, Vec2 max, Vec4 color )
GLfloat matrix[] = {
2.0f / buffer->width,  0,  0, 0,
0, 2.0f / buffer->height,  0, 0,
0, 0,                      1, 0,
  -1, -1,                     0, 1
};
 
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
 
glMultMatrixf( matrix );
 
GLfloat triangles[] = {
        min.X, min.Y,
        max.X, min.Y, 
        max.X, max.Y,
 
min.X, min.Y,
min.X, max.Y,
max.X, max.Y
    };
 
GLfloat colors[] = {
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
 
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W,
color.X, color.Y, color.Z, color.W
};
 
    glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, triangles);
 
glEnableClientState( GL_COLOR_ARRAY );
glColorPointer( 4, GL_FLOAT, 0, colors );
 
    glDrawArrays(GL_TRIANGLES, 0, 6);
 
glDisableClientState( GL_COLOR_ARRAY );
glDisableClientState( GL_VERTEX_ARRAY );
glDisable( GL_BLEND );

Bitmap rendering:

 
void DrawBitmap( ScreenBuffer* buffer, Bitmap* bitmap, Rect destRect, real32 alpha, Rect clip = { 0, 0, 1, 1} )
{
if( bitmap->textureMap == -1 )
{
glGenTextures(1, ( GLuint* ) &bitmap->textureMap);
}
 
glBindTexture(GL_TEXTURE_2D, bitmap->textureMap );
glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA8, bitmap->width, bitmap->height,
0, GL_BGRA_EXT, GL_UNSIGNED_BYTE, bitmap->pixels );
 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
 
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_CLAMP);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_CLAMP);
 
glTexEnvi( GL_TEXTURE_ENV, GL_TEXTURE_ENV_MODE, GL_MODULATE );
 
glEnable( GL_TEXTURE_2D );
 
glEnable (GL_BLEND);
glBlendFunc (GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
 
glMatrixMode( GL_TEXTURE );
glLoadIdentity();
 
glMatrixMode( GL_MODELVIEW );
glLoadIdentity();
 
GLfloat matrix[] = {
2.0f / buffer->width,  0,  0, 0,
0, 2.0f / buffer->height,  0, 0,
0, 0,                      1, 0,
  -1, -1,                     0, 1
};
glMultMatrixf( matrix );
 
glMatrixMode( GL_PROJECTION );
glLoadIdentity(); 
 
 
Vec2 min = destRect.minCorner;
Vec2 max = destRect.maxCorner;
GLfloat triangles[] = {
        min.X, min.Y,
        max.X, min.Y, 
        max.X, max.Y,
 
min.X, min.Y,
        min.X, max.Y, 
        max.X, max.Y,
};
 
GLfloat textureVertices[] = {
        clip.minCorner.X, clip.minCorner.Y,
clip.maxCorner.X, clip.minCorner.Y,
clip.maxCorner.X, clip.maxCorner.Y,
 
clip.minCorner.X, clip.minCorner.Y,
clip.minCorner.X, clip.maxCorner.Y,
clip.maxCorner.X, clip.maxCorner.Y, 
};
 
    glEnableClientState(GL_VERTEX_ARRAY);
glVertexPointer(2, GL_FLOAT, 0, triangles);
 
glEnableClientState( GL_TEXTURE_COORD_ARRAY);
glTexCoordPointer( 2, GL_FLOAT, 0, textureVertices );
    glDrawArrays(GL_TRIANGLES, 0, 6);
 
glDisableClientState(GL_TEXTURE_COORD_ARRAY);
glDisableClientState(GL_VERTEX_ARRAY);
 
glPopMatrix();

again, probably I am missing something about the matrices stack, and how it works, bacause as you can see from the image if I draw just rect they are rendered perfectly.

Note: I am drawing a rect as background, that's the reason why in rect.png there is a gray background.

Again, sorry for the ridicoulus questions, the fact is that now the position is correct and the texture are rendered in the right way, just the rects colors are wrong.

 

Leonardo

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