I'm quite new to OpenGL ES and I'm trying to draw some textured quads. I want to keep it 2D so I decided to use orthographic projection. What I really want is to draw a plane that takes the same relative amount of screen space on every device regardless the screen resolution.
The problem I encounter is the setup of the orthographic projection. The aspect ratio just isn't correct. A square is drawn as a rectangle in the height. This is my code so far:
The Renderer:
// automatically looped by android
public void onDrawFrame(GL10 gl) {
// clear screen and buffer
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
// Draw elements
for (GameObject object : level.getGameObjects()) {
gl.glScalef(0.2f, 0.2f, 0.0f);
object.draw(gl);
gl.glLoadIdentity();
}
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
gl.glViewport(0, 0, width, height);
gl.glOrthof(0f, 480f, 0f, 800f, -1f, 1f);
}
public void onSurfaceCreated(GL10 gl, EGLConfig config) {
// Load all textures
for (GameObject object : level.getGameObjects()) {
object.bindTexture(gl);
}
// Initialize game canvas
gl.glEnable(GL10.GL_TEXTURE_2D); // Enable Texture Mapping
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f); // Black background
// enable texture transparency
gl.glEnable(GL10.GL_BLEND);
gl.glBlendFunc(GL10.GL_SRC_ALPHA, GL10.GL_ONE_MINUS_SRC_ALPHA);
}
The draw method is exactly the same as in this tutorial: http://obviam.net/index.php/texture-mapping-opengl-android-displaying-images-using-opengl-and-squares/
Kind regards,
Daan
Why are you hardcoding the width and height to glOrthof? Shouldn't you use the passed in width and height?
gl.glOrthof(0f, width, 0f, height, -1f, 1f);
I have found the answer to my problem. First of all I was hardcoding the width and height wich wasn't a good option. To have a fixed with on all screen resolutions i now calculate the aspect ratio and for the height I use the with multiplied by the aspect ratio.
Another problem was the fact that I hadn't reset the projection matrix prior to setting the glortho. I have changed all this and it solved the problem:
public void onSurfaceChanged(GL10 gl, int width, int height) {
gl.glViewport(0, 0, width, height);
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
gl.glOrthof(0f, 320, 0f, 320*aspect, -1f, 1f);
}
I hope this will be helpfull for somebody.
Kind regards,
Daan
Looks like you've solved it. Can you provide details on how you calculated the aspect variable (a division of height and width perhaps?) Just as an FYI, the height and width values passed in to the onSurfaceChanged() event are indeed dynamic. For instance, they are reversed when you flip the screen orientation.
I'm relatively new to this as well, but in my desktop gl experience, it's important to factor these in when a window size changes.
Related
I'm creating an app, which should draw objects in constant place on the scene, but when i move my phone around, camera should change view and i should see all object around (when i do full rotation with phone).
When i use gl.glMultMatrixf(rotationMatrix, 0) in my onDrawFrame method and then draw object its working perfect (rotation matrix is obtained from SensorManager)
#Override
public void onDrawFrame(GL10 gl) {
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.0f);
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glLoadIdentity();
gl.glMultMatrixf(rotationMatrix, 0);
gl.glTranslatef(0f, 0f, -10f);
//draw object
pyramid.draw(gl);
}
#Override
public void onSurfaceChanged(GL10 gl, int width, int height) {
gl.glViewport(0, 0, width, height);
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f, 100.0f);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
}
But when i try to use:
GLU.gluLookAt( gl, 0.0f, 0.0f, 0.0f, x, y, z, 0.0f, 1.0f, 0.0f );
gl.glPushMatrix();
//draw object
pyramid.draw(gl);
my object is all time in the same place on screen and follow camera movement. What I'm doing wrong in second example ?
I think you are unclear on what glulookat() actually does. You are asking for a matrix representing glulookat(currentrotationmatrix, mylocation.x, mylocation.y, mylocation.z, whereImlooking.x, whereImlooking.y, whereImlooking.z, upvector.x, upvector.y, upvector.z)
So with that code you are telling opengl to rotate everything, (assuming that code is still present) and then you are saying "I am at origin (0.0, 0.0, 0.0) and looking at xyz" (not sure what xyz is in your case. or what effect you are trying to achieve.)
I am writing a game which uses opengles. I have created my renderer class and have a sample of my game working on the emulator, however none of the texures display on an actual device. I have read about the most common cause for this being the need for texture to be a factor of 2 however I have tried drawing a square (128x128) with a texture of the same size mapped to it and this only shows on the emulator. Further to that my actual game will be using rectangles so I'm unsure how I can map textures that are squares to rectangles..
This is my code so far (The game is 2d so I'm using ortho mode):
EDIT: I have updated my code, it is now correctly binding textures and using textures of size 128x128, still only seeing textures on the emulator..
public void onSurfaceCreated(GL10 gl, EGLConfig config)
{
byteBuffer = ByteBuffer.allocateDirect(shape.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
vertexBuffer = byteBuffer.asFloatBuffer();
vertexBuffer.put(cardshape);
vertexBuffer.position(0);
byteBuffer = ByteBuffer.allocateDirect(shape.length * 4);
byteBuffer.order(ByteOrder.nativeOrder());
textureBuffer = byteBuffer.asFloatBuffer();
textureBuffer.put(textureshape);
textureBuffer.position(0);
// Set the background color to black ( rgba ).
gl.glClearColor(0.0f, 0.0f, 0.0f, 0.5f);
// Enable Smooth Shading, default not really needed.
gl.glShadeModel(GL10.GL_SMOOTH);
// Depth buffer setup.
gl.glClearDepthf(1.0f);
// Enables depth testing.
gl.glEnable(GL10.GL_DEPTH_TEST);
// The type of depth testing to do.
gl.glDepthFunc(GL10.GL_LEQUAL);
// Really nice perspective calculations.
gl.glHint(GL10.GL_PERSPECTIVE_CORRECTION_HINT, GL10.GL_NICEST);
gl.glEnable(GL10.GL_TEXTURE_2D);
loadGLTexture(gl);
}
public void onDrawFrame(GL10 gl) {
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
gl.glDisable(GL10.GL_DEPTH_TEST);
gl.glMatrixMode(GL10.GL_PROJECTION); // Select Projection
gl.glPushMatrix(); // Push The Matrix
gl.glLoadIdentity(); // Reset The Matrix
gl.glOrthof(0f, 480f, 0f, 800f, -1f, 1f);
gl.glMatrixMode(GL10.GL_MODELVIEW); // Select Modelview Matrix
gl.glPushMatrix(); // Push The Matrix
gl.glLoadIdentity(); // Reset The Matrix
gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
gl.glLoadIdentity();
gl.glTranslatef(card.x, card.y, 0.0f);
gl.glBindTexture(GL10.GL_TEXTURE_2D, card.texture[0]); //activates texture to be used now
gl.glVertexPointer(2, GL10.GL_FLOAT, 0, vertexBuffer);
gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
gl.glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
gl.glDisableClientState(GL10.GL_VERTEX_ARRAY);
gl.glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
}
public void onSurfaceChanged(GL10 gl, int width, int height) {
// Sets the current view port to the new size.
gl.glViewport(0, 0, width, height);
// Select the projection matrix
gl.glMatrixMode(GL10.GL_PROJECTION);
// Reset the projection matrix
gl.glLoadIdentity();
// Calculate the aspect ratio of the window
GLU.gluPerspective(gl, 45.0f, (float) width / (float) height, 0.1f,
100.0f);
// Select the modelview matrix
gl.glMatrixMode(GL10.GL_MODELVIEW);
// Reset the modelview matrix
gl.glLoadIdentity();
}
public int[] texture = new int[1];
public void loadGLTexture(GL10 gl) {
// loading texture
Bitmap bitmap;
bitmap = BitmapFactory.decodeResource(context.getResources(), R.drawable.image);
// generate one texture pointer
gl.glGenTextures(0, texture, 0); //adds texture id to texture array
// ...and bind it to our array
gl.glBindTexture(GL10.GL_TEXTURE_2D, texture[0]); //activates texture to be used now
// create nearest filtered texture
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER, GL10.GL_NEAREST);
gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MAG_FILTER, GL10.GL_LINEAR);
// Use Android GLUtils to specify a two-dimensional texture image from our bitmap
GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, bitmap, 0);
// Clean up
bitmap.recycle();
}
Is there anything I have done wrong? Or something I haven't done? It works perfectly fine in the emulator so I could only assume it was the power of 2 issue but like I said I tried that using a 128x128 texture on a square but it didn't show.. any help would be appreciated..
EDIT: I have also tried setting the minsdkversion is 3, loading the bitmap via an input stream bitmap = BitmapFactory.decodeStream(is), setting BitmapFactory.Options.inScaled to false, putting the images in the nodpi folder and then trying them in the raw folder.. any other ideas?
I'm actually looking for the solution to a similar problem right now. I think I might have a temporary fix for you, however.
The problem appears to be that on the emulator the orthographic view is flipped. To solve this, in my app we added an option in preferences to manually flip the view if nothing draws. Here's the snippet that handles this:
if (!flipped)
{
glOrthof(0, screenWidth, screenHeight, 0, -1, 1); //--Device
}
else
{
glOrthof(0, screenWidth, 0, -screenHeight, -1, 1); //--Emulator
}
Hope this helps! If anybody has a more general solution, I'd be happy to hear it!
I didn't look at your code but I have been on that road before. Developing in OpenGL is a real pain in the ass. If you are not obligated to use OpenGL, then use a graphics engine. Unity is a great one and it's free. Also your game would work on Android, iOS or other platforms. Study your choices carefully. Good luck..
I have an OpenGL ES object which I am trying to draw. The object has fairly large vertice values with the x and y co-ordinates lying between -30,000 and +30,000. The z values are between 2000 and -2000.
Can anybody advise me how I should be setting up my viewport ? I am using the following code :
public void onSurfaceChanged(GL10 gl, int width, int height) {
//Define the view frustrum
gl.glViewport(0, 0, width, height);
gl.glMatrixMode(GL10.GL_PROJECTION);
gl.glLoadIdentity();
float ratio = (float)width/height;
GLU.gluPerspective(gl, 45.0f, ratio, 1, 100f);
}
public void onDrawFrame (GL10 gl) {
// Clear the screen to black.
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
//Position the model.
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
gl.glTranslatef(0.0f, 0.0f, 0.0f);
//gl.glScalef(0.000015f,0.000015f,0.000015f);
This compiles ok, but I cannot see my object at all.
Thank you.
You probably can't see it because your camera's inside the object. Maybe try first scaling it by 0.001 to get it down to about 60 units across, translate it by -50 in the z direction (to get it to the middle of your z range), and see if it shows up then.
Alternatively you could just make your z-range a lot bigger, and translate it by some -50,000 units in the z direction to move the object back from the camera. You'll have to adjust znear/zfar then to be much larger.
I'm trying to get my rendering-to-texture working. So far, it does all the necessary GL gubbins to draw on the texture and everything - the only problem is its getting the scaling all off.
I figured I'd want to set the viewport to the size of the texture, and the gluOrtho2d (the way I'm going to be drawing onto the texture) as -halfwidth, halfwidth, -halfheight, halfheight. This means when drawing position 0,0 should be in the center. A position of halfwdith, halfheight should be in the top right corner etc etc.
I'm getting really weird effects though, it seems that its not drawing on the texture in the right scale - so everything gets skewed, can anyone suggest what I might be doing wrong?
Thanks
public void renderToTexture(GLRenderer glRenderer, GL10 gl)
{
boolean checkIfContextSupportsExtension = checkIfContextSupportsExtension(gl, "GL_OES_framebuffer_object");
if(checkIfContextSupportsExtension)
{
GL11ExtensionPack gl11ep = (GL11ExtensionPack) gl;
int mFrameBuffer = createFrameBuffer(gl,texture.getWidth(), texture.getHeight(), texture.getGLID());
if (mFrameBuffer == -1)
{
return;
}
gl11ep.glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, mFrameBuffer);
int halfWidth = texture.getWidth()/2;//width/2;
int halfHeight = texture.getHeight()/2;//height/2;
gl.glViewport(0,0,texture.getWidth(), texture.getHeight());
gl.glLoadIdentity();
GLU.gluOrtho2D(gl, -halfWidth, halfWidth , -halfHeight, halfHeight);
gl.glMatrixMode(GL10.GL_MODELVIEW);
gl.glLoadIdentity();
gl.glClearColor(0f, 1f, 0f, 1f);
gl.glClear(GL10.GL_COLOR_BUFFER_BIT | GL10.GL_DEPTH_BUFFER_BIT);
//draw the old version of the texture to framebuffer:
Quad quad = new Quad(texture.getWidth(), texture.getHeight());
quad.setTexture(texture);
SpriteRenderable sr = new SpriteRenderable(quad);
sr.renderTo(glRenderer, gl, 1);
//draw the new gl objects etc to framebuffer
for (Renderable renderable : renderThese)
{
if (renderable.isVisible()) {
renderable.renderTo(glRenderer, gl, 1);
}
}
//default to the old framebuffer
gl11ep.glBindFramebufferOES(GL11ExtensionPack.GL_FRAMEBUFFER_OES, 0);
}
}
images:
This one is the game prior to any texture rendering.
image1
This is after the "blood splats" (currently pigs!) are rendered on the "arena" background texture shown in picture 1. Notice that the original texture has shrunk too small to see in the middle (its a few pixles) and the pig "blood splat" jumps in a zig-zag, flipping over the center of the texture and becoming smaller...
image2
(sorry, dont have enough rep to post images in the post!)
Just a speculative guess, but do you remember to set matrixMode to GL_PROJECTION prior to entering renderToTexture function? It's not set inside the function, where it seems like it should be. Also don't forget to restore projection matrix and viewport at the end of the function.
I'm trying to make a copy of MineCraft in Java using OpenGL (LWJGL). The problem I'm facing is that everything of my 2D overlay (aiming cross in the middle, menus, etc...) are all white. The 3D part of the game works great: every cube has a texture on each side.
But when I try to draw the overlay, as I said, every texture is white, but I can see the shape of it (because it has transparent areas). I'll add a picture of it.
(This is supposed to be the inventory)
As you can see, the overlay is completely white. And it should look like this:
I'm already searching the web for hours. Can't seem to find a solution.
This drives my crazy... I already searched for instructions of how to create a 2D overlay on a 3D scene, but they don't help either. So I though, I'll give StackOverflow a try.
Hopefully someone can help me?
Thanks for reading my question and for the (hopefully coming) answers!
Martijn
Here is the code:
Initialising OpenGL
public void initOpenGL() throws IOException
{
// init OpenGL
glMatrixMode(GL_PROJECTION);
glLoadIdentity();
glOrtho(0, 800, 600, 0, 1, 300);
glMatrixMode(GL_MODELVIEW);
float color = 0.9f;
glClearColor(color, color, color, color);
glEnable(GL_TEXTURE_2D);
glHint(GL_PERSPECTIVE_CORRECTION_HINT, GL_NICEST);
glShadeModel(GL_FLAT);
glEnable(GL_DEPTH_TEST);
glDepthFunc(GL_LEQUAL);
glEnable(GL_LINE_SMOOTH);
glEnable(GL_CULL_FACE);
glEnable(GL_FOG);
glFog(GL_FOG_COLOR, MineCraft.wrapDirect(color, color, color, 1.0f));
glFogi(GL_FOG_MODE, GL_LINEAR);
glFogf(GL_FOG_START, _configuration.getViewingDistance() * 0.8f);
glFogf(GL_FOG_END, _configuration.getViewingDistance());
glFogi(NVFogDistance.GL_FOG_DISTANCE_MODE_NV, NVFogDistance.GL_EYE_RADIAL_NV);
glHint(GL_FOG_HINT, GL_NICEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
}
Configuring the matrixes for drawing the overlay (Out of inspiration, I literally copied all the OpenGL calls for this method from BlockMania (another open-source MineCraft copy), which works great)
public void renderOverlay()
{
glMatrixMode(GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
GLU.gluOrtho2D(0, conf.getWidth(), conf.getHeight(), 0);
glMatrixMode(GL_MODELVIEW);
glEnable(GL_COLOR_MATERIAL);
glPushMatrix();
glLoadIdentity();
glDisable(GL_CULL_FACE);
glDisable(GL_DEPTH_TEST);
glEnable(GL_BLEND);
glBlendFunc(GL_SRC_ALPHA, GL_ONE_MINUS_SRC_ALPHA);
/** RENDER **/
if (_activatedInventory != null)
{
_activatedInventory.renderInventory();
}
glDisable(GL_BLEND);
glEnable(GL_DEPTH_TEST);
glEnable(GL_CULL_FACE);
glPopMatrix();
glMatrixMode(GL_PROJECTION);
glPopMatrix();
glMatrixMode(GL_MODELVIEW);
}
Drawing the texture itself:
public void renderInventory()
{
Configuration conf = Game.getInstance().getConfiguration();
glTranslatef(conf.getWidth() / 2.0f, conf.getHeight() / 2.0f, 0.0f);
glEnable(GL_TEXTURE_2D);
Texture tex = TextureStorage.getTexture("gui.inventory");
tex.bind(); // newdawn.slick (same library for my whole program, so this works)
float hw = 170; // half width
float hh = 163; // half height
Vector2f _texPosUpLeft = new Vector2f(3, 0);
Vector2f _texPosDownRight = new Vector2f(_texPosUpLeft.x + hw, _texPosUpLeft.y + hh);
_texPosUpLeft.x /= tex.getTextureWidth();
_texPosUpLeft.y /= tex.getTextureHeight();
_texPosDownRight.x /= tex.getTextureWidth();
_texPosDownRight.y /= tex.getTextureHeight();
glColor3f(1, 1, 1); // Changes this doesn't make any effect
glBegin(GL_QUADS);
glTexCoord2f(_texPosUpLeft.x, _texPosUpLeft.y);
glVertex2f(-hw, -hh);
glTexCoord2f(_texPosDownRight.x, _texPosUpLeft.y);
glVertex2f(hw, -hh);
glTexCoord2f(_texPosDownRight.x, _texPosDownRight.y);
glVertex2f(hw, hh);
glTexCoord2f(_texPosUpLeft.x, _texPosDownRight.y);
glVertex2f(-hw, hh);
glEnd();
}
(The texture pack I'm using is CUBISM1.00)
I found it!!
It was the fog. For one or another reason it looks like it thinks the overlay is out of sight and gives it the color of the fog. So, disabling the fog before rendering the overlay solved it.
glDisable(GL_FOG);
/* Render overlay here */
glEnable(GL_FOG);
If there are still people who read this, is this caused by matrix abuse or is this behaviour normal?