I am trying to write code that will cycle between rendering an animation and rendering a heads up display. The animation works, however I am having difficulty switching between the animation's projection matrix and another orthographic projection matrix for the HUD.
The main loop runs as follows:
init();
while (isAnimationRunning) {
drawAnimation();
drawHUD();
}
And the initialization of the surface is:
void init(){
glEnableClientState(GL10.GL_VERTEX_ARRAY);
glClearColor(1, 1, 1, 1);
glMatrixMode(GL11.GL_PROJECTION);
glLoadIdentity();
glViewport(0, 0, windowWidth, windowHeight);
GLU.gluPerspective(gl11, 45.0f, windowWidth / windowHeight, 0.1f, 100.0f);
}
And the code for the animation rendering
void drawAnimation() {
glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
glMatrixMode(GL10.GL_MODELVIEW);
glLoadIdentity();
GLU.gluLookAt(gl11, x, y, zoom, x, y, 0, 0, 1, 0);
drawAnimationTextures();
}
And the code for the HUD rendering
void drawHUD(){
glMatrixMode(GL10.GL_MODELVIEW);
glPushMatrix();
// IF THIS LINE IS REMOVED THE ANIMATION DISPLAYS BUT NOT THE HUD
glLoadIdentity();
glClear(GL10.GL_COLOR_BUFFER_BIT);
GLU.gluLookAt(gl11, 0, 0, 2, 0, 0, 0, 0, 1, 0);
glMatrixMode(GL10.GL_PROJECTION);
glPushMatrix();
glLoadIdentity();
GLU.gluPerspective(gl11, 45, aspectRatio, 0.1f, 100.0f);
glOrthof(-aspectRatio, aspectRatio, -1, 1, -4, 4);
drawHUDTexture();
glPopMatrix();
glMatrixMode(GL10.GL_MODELVIEW);
glPopMatrix();
}
The screen is blank when this code is implemented. Any ideas what the problem might be?
////////////////////////
void drawTexture(float x, float y, float z, float sizeX, float sizeY,...){
glEnable(GL10.GL_TEXTURE_2D);
glPushMatrix();
bindTexture(texture);
glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
glFrontFace(GL10.GL_CW);
glColor4f(RGB[0], RGB[1], RGB[2], alpha);
glTranslatef(x, y, z);
glScalef(sizeX, sizeY, sizeZ);
glVertexPointer(3, GL10.GL_FLOAT, 0, squareVertexBuffer);
glTexCoordPointer(2, GL10.GL_FLOAT, 0, textureBuffer);
glDrawArrays(GL10.GL_TRIANGLE_STRIP, 0, 4);
glDisableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
glPopMatrix();
}
Why are you clearing the framebuffer in both routines? You should call it once only in your top level loop. If the animation appears when you comment out the loadidentity but still have the glclear there I am puzzled.
It looks like the hud overwrites the whole screen, make it semi transparent to check this, it may be so large you're just seeing a small part of it.
plus your hud code is setting up a perspective view, then an ortho view - which one do you want?
Related
Hi I am working on a AR android app. I am using ARToolkit6. In this app I want to view my 3D object( A Cube) on left half of the screen. With this eventually I want to display 3 cubes on the screen each on 1/3 of the screen area.
I was able to scale the 3D object by tweaking ModelView Matrix. What I read so far, I think I need to tweak projection matrix to achieve my goal. I tried looking solutions online. But Couldn't get it to work. Can anyone direct me to right path?
for (int trackableUID : trackableUIDs) {
// If the marker is visible, apply its transformation, and render a cube
if (ARToolKit.getInstance().queryMarkerVisible(trackableUID)) {
float[] projectionMatrix = ARToolKit.getInstance().getProjectionMatrix();
float[] modelViewMatrix = ARToolKit.getInstance().queryMarkerTransformation(trackableUID);
float[] scalingMat = {1, 0, 0, 0, 0, 3.0f, 0, 0, 0, 0, 1.0f, 0, 0.0f, 0, 0, 1};
float[] newModelView = modelViewMatrix;
multiplyMM(newModelView, 0, modelViewMatrix, 0, scalingMat, 0);
cube.draw(projectionMatrix, newModelView);
}
I followed the this link Set origin to top-left corner of screen in OpenGL ES 2 and (OpenGL ES) Objects away from view centre are stretched. So I translated the modelView Matrix but it doesn't solve the problem, the 3D object appears at the center of the screen. Can you explain how should I approach this problem? Thanks
#Override
public void draw() {
super.draw();
GLES20.glEnable(GLES20.GL_CULL_FACE);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
GLES20.glFrontFace(GLES20.GL_CCW);
// Look for trackables, and draw on each found one.
for (int trackableUID : trackableUIDs) {
// If the marker is visible, apply its transformation, and render a cube
if (ARToolKit.getInstance().queryMarkerVisible(trackableUID)) {
float[] projectionMatrix = ARToolKit.getInstance().getProjectionMatrix();
float[] modelViewMatrix = ARToolKit.getInstance().queryMarkerTransformation(trackableUID);
float[] scalingMat = {1, 0, 0, 0, 0, 3.0f, 0, 0, 0, 0, 1.0f, 0, 0.0f, 0, 0, 1};
multiplyMM(modelViewMatrix, 0, scalingMat, 0, modelViewMatrix, 0);
float[] rightModelMatrix = new float[16];
Matrix.setIdentityM(rightModelMatrix, 0);
// Translate outer sphere by 5 in x.
Matrix.translateM(rightModelMatrix, 0, 5.0f, 0.0f, 0.0f);
Matrix.multiplyMM(modelViewMatrix, 0, rightModelMatrix, 0, modelViewMatrix, 0);
cube.draw(projectionMatrix, modelViewMatrix);
}
}
Also tried this but the object gets displayed at the center of the screen.
glMatrixMode(GL_PROJECTION);
glTranslatef(5f, 0f, 0f);
I am having some problems with proper scene manipulations with OpenGL ES 2.0. On my screen I want to draw a rectangle and a cube. Rectangle should be moved to the bottom and scaled while cube should be moved to the top and scaled. What's more, I want to rotate this cube in all 3 axis.
This is what I've created so far:
#Override
public void onDrawFrame(GL10 gl) {
float[] scratch = new float[16];
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
Matrix.setLookAtM(viewMatrix, 0, 0, 0, -6, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
Matrix.multiplyMM(MVPMatrix, 0, projectionMatrix, 0, viewMatrix, 0);
Matrix.translateM(scratchMatrix1, 0, 0, -1.1f, 0);
Matrix.scaleM(scratchMatrix3, 0, 0.5f, 0.5f, 0.5f);
Matrix.multiplyMM(scratchMatrix2, 0, scratchMatrix1, 0, scratchMatrix3, 0);
Matrix.multiplyMM(scratch, 0, scratchMatrix2, 0, MVPMatrix, 0);
rectangle.draw(scratch);
Matrix.setRotateM(scratchMatrix1, 0, angleXVal, 1.0f, 0, 0);
Matrix.setRotateM(rotationMatrix, 0, angleYVal, 0, 1.0f, 0);
Matrix.multiplyMM(scratchMatrix2, 0, rotationMatrix, 0, scratchMatrix1, 0);
Matrix.setRotateM(rotationMatrix, 0, angleZVal, 0, 0, 1.0f);
Matrix.multiplyMM(scratchMatrix3, 0, rotationMatrix, 0, scratchMatrix2, 0);
Matrix.translateM(scratchMatrix1, 0, 0, 0.3f, 0);
Matrix.multiplyMM(scratchMatrix2, 0, scratchMatrix3, 0, scratchMatrix1, 0);
Matrix.scaleM(scratchMatrix1, 0, 0.8f, 0.8f, 0.8f);
Matrix.multiplyMM(scratchMatrix3, 0, scratchMatrix2, 0, scratchMatrix1, 0);
Matrix.multiplyMM(scratch, 0, scratchMatrix2, 0, MVPMatrix, 0);
cube.draw(scratch);
}
The problem is that when I am rotating the cube also the rectangle is moving. It is this same with scale and translating of cube - it is pulling the rectangle.
For me it looks like the matrices are connected somewhere but I don't see where, because the rectangle is drawn first and scratch matrix is overwritten later.
Assuming that is your complete onDrawFrame() code, scratchMatrix1 etc are class member variables that persist from frame to frame.
That means that translations from one frame will carry over to the next, because Matrix.translateM() applies a translation to an existing matrix transform by adding to it, rather than setting the matrix to a given translation matrix and overwriting the previous values. So the translations will accumulate over several frames.
That means that when you translate the cube, the translation will still be sitting in scratchMatrix1 the next time onDrawFrame is called, and the rectangle translation will be added to it rather than be set afresh.
The same goes for Matrix.scaleM().
You can rectify this by initializing all the scratch matrices to identity at the start of the function, and again before beginning the calculation of the cube transform matrix:
Matrix.setIdentityM(scratchMatrix1, 0);
Matrix.setIdentityM(scratchMatrix2, 0);
Matrix.setIdentityM(scratchMatrix3, 0);
Matrix.setIdentityM(scratch, 0);
I have, a problem with the setLookAtM function. My goal is to create a cube within a cube something like this (yep, it's paint :P ):
So basically everything works... almoust... I have the smaller cube and I have the bigger one.
However, there is a problem. I created the bigger one with coords from -1 to 1 and now I want to upscale it. With scale 1.0f i have something like this (the inner cube is rotating):
And thats good, but now... when I try to scale the bigger cube (so that it looks like in the paint drawing) the image goes black or white (i guess it's because the "camera" looks at the white cube but still i dont know why does my inner cube disappear :/ I don't understand what I'm doing wrong. Here is my code:
public void onDrawFrame(GL10 unused) {
float[] scratch = new float[16];
GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -5.0f, 0f, 0f, -1.0f, 0f, 1.0f, 0.0f);
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mViewMatrix, 0);
mRoom.mScale = 1.0f;
Matrix.setIdentityM(mScaleMatrix, 0);
Matrix.scaleM(mScaleMatrix, 0, mRoom.mScale, mRoom.mScale, mRoom.mScale);
float[] scaleTempMatrix = new float[16];
Matrix.multiplyMM(scaleTempMatrix, 0, mMVPMatrix, 0, mScaleMatrix, 0);
mRoom.draw(scaleTempMatrix);
When I set for example:
mRoom.mScale = 3.0f;
And
Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -2.0f, 0f, 0f, 0.0f, 1.0f, 1.0f, 0.0f);
My camera should be at (0, 0, -2) looking at (0,0, -1) and it should be inside the white cube (since scale is 3.0 so the coords should be from -3 to 3 right?) But all I get is a white screen without the smaller cube rotating inside :/
If your scale is 3x in this code, then your visible coordinate range is actually going to be [-1/3,1/3].
You are thinking about things backwards, it might help if you considered the order in which the scale operation is applied. Right now you are scaling the object-space coordinates, then applying the view matrix and then projection. It may not look that way, but that is how matrix multiplication in GL works; GL effectively flips the operands when it does matrix multiplication and matrix multiplication is not commutative.
I believe this is what you actually want:
public void onDrawFrame(GL10 unused) {
float[] scratch = new float[16];
GLES20.glClear(GLES20.GL_DEPTH_BUFFER_BIT | GLES20.GL_COLOR_BUFFER_BIT);
GLES20.glEnable(GLES20.GL_DEPTH_TEST);
Matrix.setLookAtM(mViewMatrix, 0, 0, 0, -5.0f, 0f, 0f, -1.0f, 0f, 1.0f, 0.0f);
mRoom.mScale = 3.0f;
Matrix.setIdentityM(mScaleMatrix, 0);
Matrix.scaleM(mScaleMatrix, 0, mRoom.mScale, mRoom.mScale, mRoom.mScale);
Matrix.multiplyMM(mMVPMatrix, 0, mScaleMatrix, 0, mProjectionMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mMVPMatrix, 0, mViewMatrix, 0);
mRoom.draw(mMVPMatrix);
I'm trying to rotate moving object, but it rotates aroud the center of the coordinates system. How to make it rotate around itself while moving? The code is:
Matrix.translateM(mMMatrix, 0, 0, -y, 0);
Matrix.setRotateM(mMMatrix, 0, mAngle, 0, 0, 1.0f);
y += speed;
Matrix.translateM(mMMatrix, 0, 0, y, 0);
Don`t use the view matrix to rotate objects, this matrix is used as the camera for all the scene, To transform an object you should use the model matrix. To rotate if around its own center, you can use the following method:
public void transform(float[] mModelMatrix) {
Matrix.setIdentityM(mModelMatrix, 0);
Matrix.translateM(mModelMatrix, 0, 0, y, 0);
Matrix.rotateM(mModelMatrix, 0, mAngle, 0.0f, 0.0f, 1.0f);
}
Don`t forget use the identity matrix to reset the transformations in every loop.
I think your code is worng. You shoud update the value of 'y' before to apply any transformation.
public void onDrawFrame(GL10 gl) {
...
y += speed;
transform(mModelMatrix);
updateMVP(mModelMatrix, mViewMatrix, mProjectionMatrix, mMVPMatrix);
renderObject(mMVPMatrix);
...
}
The updateMVP method, will combine the model, view and projection matrices:
private void updateMVP(
float[] mModelMatrix,
float[] mViewMatrix,
float[] mProjectionMatrix,
float[] mMVPMatrix) {
// combine the model with the view matrix
Matrix.multiplyMM(mMVPMatrix, 0, mViewMatrix, 0, mModelMatrix, 0);
// combine the model-view with the projection matrix
Matrix.multiplyMM(mMVPMatrix, 0, mProjectionMatrix, 0, mMVPMatrix, 0);
}
And at last the render method, will execute the Shaders to paint the object:
public void renderObject(float[] mMVPMatrix) {
GLES20.glUseProgram(mProgram);
...
// Pass the MVP data into the shader
GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);
// Draw the shape
GLES20.glDrawElements (...);
}
I hope this will help you.
where do you make the object drawing?
I suppose it is after the code you have put up here, something like:
Matrix.translateM(mMMatrix, 0, 0, -y, 0);
Matrix.setRotateM(mMMatrix, 0, mAngle, 0, 0, 1.0f);
y += speed;
Matrix.translateM(mMMatrix, 0, 0, y, 0);
drawHere();//<<<<<<<<<<<<<<<<<<<
Then, the second translate call is the issue.
You should either move your draw call before the second translate.
or
the clean way to do it is:
Matrix.setIdentityM(mMMatrix, 0);//<<<<<<<<added
Matrix.translateM(mMMatrix, 0, 0, -y, 0);
Matrix.setRotateM(mMMatrix, 0, mAngle, 0, 0, 1.0f);
y += speed;
//Matrix.translateM(mMMatrix, 0, 0, y, 0); //<<<<<<<<<removed
drawHere();
I just used view matrix instead of model matrix and everything worked out. For details on model, view and projection matrices see.
I need to position sky sphere in 3D space right where camera is.
I set up camera as follows:
public void onSurfaceChanged(GL10 glUnused, int width, int height) {
// Ignore the passed-in GL10 interface, and use the GLES20
// class's static methods instead.
GLES20.glViewport(0, 0, width, height);
float ratio = (float) width / height;
Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 2, 1000);
}
...
Matrix.setLookAtM(mVMatrix, 0, 0, 0, -5, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
...
Sphere has a diameter of 100 units and it's center is in (0;0;0).
The method to draw a sphere:
private void drawSphere() {
//Matrix.setLookAtM(mVMatrix, 0, 0, 0, 0, 0f, 0f, 0f, 0f, 1.0f, 0.0f);
mTriangleVerticesSphere.position(TRIANGLE_VERTICES_DATA_POS_OFFSET);
GLES20.glVertexAttribPointer(maPositionHandle, 3, GLES20.GL_FLOAT, false, TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVerticesSphere);
mTriangleVerticesSphere.position(TRIANGLE_VERTICES_DATA_UV_OFFSET);
GLES20.glEnableVertexAttribArray(maPositionHandle);
GLES20.glVertexAttribPointer(maTextureHandle, 2, GLES20.GL_FLOAT, false, TRIANGLE_VERTICES_DATA_STRIDE_BYTES, mTriangleVerticesSphere);
GLES20.glEnableVertexAttribArray(maTextureHandle);
Matrix.setRotateM(mMMatrix, 0, jitterX, 1.0f, 0, 0);
Matrix.rotateM(mMMatrix, 0, angleYaw + jitterY, 0, 1.0f, 0);
Matrix.scaleM(mMMatrix, 0, 0.01f, 0.01f, 0.01f);
Matrix.multiplyMM(mMVPMatrix, 0, mVMatrix, 0, mMMatrix, 0);
Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mMVPMatrix, 0);
GLES20.glUniformMatrix4fv(muMVPMatrixHandle, 1, false, mMVPMatrix, 0);
GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, numPolysSphere);
}
This code displays a sphere. Backface culling is disabled, and I can see both sides of sphere (texture has transparent parts).
In order to display sphere right in the camera position I try to move camera. But if I uncomment Matrix.setLookAtM(mVMatrix, 0, 0, 0, 0, 0f, 0f, 0f, 0f, 1.0f, 0.0f) in the beginning of drawSphere() it doesn't display anything. May be it has something to do with clipping planes?
Please give an example how to position the sphere correctly.
I think your more looking to do something like
Matrix.setLookAtM(mvMatrix, 0, 0, 0, 10, 0, 0, 0, 0, 1, 0);
if I'm not wrong opengl doesn't know which way its looking at
your asking too look for (0,0,0) towards (0,0,0) while oriented towards (0,1.0,0)
OK, so I figured out how to do it.
1. Look at correct angle.
3. Draw sky sphere.
2. Clear Z-buffer.
3. Reposition camera.
4. Draw the rest.