[英]How to translate the camera in GLES2.0?
I want to create a camera moving above a tiled plane. 我想创建一个在平铺平面上方移动的相机。 The camera is supposed to move in the XY-plane only and to look straight down all the time.
相机应该只在XY平面上移动,并且一直向下看。 With an orthogonal projection I expect a pseudo-2D renderer.
使用正交投影,我期望伪2D渲染器。 My problem is, that I don't know how to translate the camera.
我的问题是,我不知道如何翻译相机。 After some research it seems to me, that there is nothing like a "camera" in OpenGL and I have to translate the whole world.
经过一些研究,在我看来,在OpenGL中没有什么像“相机”,我必须翻译整个世界。 Changing the eye-position and view center coordinates in the
Matrix.setLookAtM
-function just leads to distorted results. 更改
Matrix.setLookAtM
函数中的眼睛位置和视图中心坐标只会导致结果失真。 Translating the whole MVP-Matrix does not work either. 翻译整个MVP-Matrix也不起作用。
I'm running out of ideas now; 我现在已经没想完了; do I have to translate every single vertex every frame directly in the vertex buffer?
我是否必须直接在顶点缓冲区中每帧翻译每个顶点? That does not seem plausible to me.
这对我来说似乎不合理。
I derived GLSurfaceView
and implemented the following functions to setup and update the scene: 我派生了
GLSurfaceView
并实现了以下函数来设置和更新场景:
public void onSurfaceChanged(GL10 unused, int width, int height) {
GLES20.glViewport(0, 0, width, height);
float ratio = (float) width / height;
// Setup the projection Matrix for an orthogonal view
Matrix.orthoM(mProjMatrix, 0, -ratio, ratio, -1, 1, 3, 7);
}
public void onDrawFrame(GL10 unused) {
// Draw background color
GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
//Setup the camera
float[] camPos = { 0.0f, 0.0f, -3.0f }; //no matter what else I put in here the camera seems to point
float[] lookAt = { 0.0f, 0.0f, 0.0f }; // to the coordinate center and distorts the square
// Set the camera position (View matrix)
Matrix.setLookAtM( vMatrix, 0, camPos[0], camPos[1], camPos[2], lookAt[0], lookAt[1], lookAt[2], 0f, 1f, 0f);
// Calculate the projection and view transformation
Matrix.multiplyMM( mMVPMatrix, 0, projMatrix, 0, vMatrix, 0);
//rotate the viewport
Matrix.setRotateM(mRotationMatrix, 0, getRotationAngle(), 0, 0, -1.0f);
Matrix.multiplyMM(mMVPMatrix, 0, mRotationMatrix, 0, mMVPMatrix, 0);
//I also tried to translate the viewport here
// (and several other places), but I could not find any solution
//draw the plane (actually a simple square right now)
mPlane.draw(mMVPMatrix);
}
Changing the eye-position and view center coordinates in the "LookAt"-function just leads to distorted results.
更改“LookAt”功能中的眼睛位置和视图中心坐标只会导致失真的结果。
If you got this from the android tutorial, I think they have a bug in their code. 如果你从android教程得到这个,我认为他们的代码中有一个错误。 (made a comment about it here )
(在这里发表评论)
Try the following fixes: 请尝试以下修复:
In the shader, change the gl_Position
line 在着色器中,更改
gl_Position
行
from: " gl_Position = vPosition * uMVPMatrix;"
来自:
" gl_Position = vPosition * uMVPMatrix;"
to: " gl_Position = uMVPMatrix * vPosition;"
to:
" gl_Position = uMVPMatrix * vPosition;"
I'd think the //rotate the viewport
section should be removed as well, as this is not rotating the camera properly. 我认为
//rotate the viewport
部分也应该被移除,因为这不能正确旋转相机。 You can change the camera's orientation in the setlookat function. 您可以在setlookat功能中更改相机的方向。
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