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POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
 

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  1. POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
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    <p>My code is almost exactly the same as the code on the website, with a few variable name changes: </p> <pre><code>package com.example.opengltraining; import java.nio.ByteBuffer; import java.nio.ByteOrder; import java.nio.FloatBuffer; import javax.microedition.khronos.egl.EGLConfig; import javax.microedition.khronos.opengles.GL10; import android.opengl.GLES20; import android.opengl.GLSurfaceView; import android.opengl.Matrix; public class MyGL20Renderer implements GLSurfaceView.Renderer{ private Triangle triangle1; private final float[] mProjMatrix = new float[16]; private final float[] mVMatrix = new float[16]; private final float[] mMVPMatrix = new float[16]; private final float[] mRotationMatrix = new float[16]; public static int loadShader(int type, String shaderCode){ //create vertex shader type //or fragment shader type int shader = GLES20.glCreateShader(type); //add source code to shader and compile GLES20.glShaderSource(shader, shaderCode); GLES20.glCompileShader(shader); return shader; } public void redrawTriangle(float[]triangleCoords){ triangle1.changeTriangle(triangleCoords); } public void onSurfaceCreated(GL10 unused, EGLConfig config){ //set background fram color GLES20.glClearColor(1f,0.5f, 0.25f, .5f); triangle1 = new Triangle(); } public void onDrawFrame(GL10 unused) { // Draw background color GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT); // Set the camera position (View matrix) Matrix.setLookAtM(mVMatrix, 0, 0, 0, -3, 0f, 0f, 0f, 0f, 1.0f, 0.0f); // Calculate the projection and view transformation Matrix.multiplyMM(mMVPMatrix, 0, mProjMatrix, 0, mVMatrix, 0); // Draw triangle triangle1.draw(mMVPMatrix); } public void onSurfaceChanged(GL10 unused, int width, int height){ GLES20.glViewport(0, 0, width, height); float ratio = (float) width / height; //applies projection matrix to object coordinates Matrix.frustumM(mProjMatrix, 0, -ratio, ratio, -1, 1, 2, 7); } } class Triangle{ //shaders - vertex private final String vertexShaderCode = "attribute vec4 vPosition;" + "void main() {" + " gl_Position = vPosition;" + "}"; //shaders - fragment private final String fragmentShaderCode = "precision mediump float;" + "uniform vec4 vColor;" + "void main() {" + " gl_FragColor = vColor;" + "}"; private FloatBuffer vertexBuffer; private final int mProgram; private int mPositionHandle; private int mColorHandle; private int mMVPMatrixHandle; //number of coordinates per vertex in this array static final int COORDS_PER_VERTEX = 3; static float triangleCoords[] = { // in counterclockwise order: 0.0f, 0.5f, 0.0f, // top -0.5f, -0.25f, 0.0f, // bottom left 0.5f, -0.25f, 0.0f // bottom right }; private final int vertexCount = triangleCoords.length / COORDS_PER_VERTEX; private final int vertexStride = COORDS_PER_VERTEX * 4; //color of triangle float color[] = { 0f, 1f, 0f, 1.0f }; public void draw(float[] mvpMatrix) { // Add program to OpenGL environment GLES20.glUseProgram(mProgram); // get handle to vertex shader's vPosition member mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition"); // Enable a handle to the triangle vertices GLES20.glEnableVertexAttribArray(mPositionHandle); // Prepare the triangle coordinate data GLES20.glVertexAttribPointer(mPositionHandle, COORDS_PER_VERTEX, GLES20.GL_FLOAT, false, vertexStride, vertexBuffer); // get handle to fragment shader's vColor member mColorHandle = GLES20.glGetUniformLocation(mProgram, "vColor"); // Set color for drawing the triangle GLES20.glUniform4fv(mColorHandle, 1, color, 0); // get handle to shape's transformation matrix mMVPMatrixHandle = GLES20.glGetUniformLocation(mProgram, "uMVPMatrix"); // Apply the projection and view transformation GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mvpMatrix, 0); // Draw the triangle GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, vertexCount); // Disable vertex array GLES20.glDisableVertexAttribArray(mPositionHandle); } public void changeTriangle(float [] newTriangleCoords){ ByteBuffer bb = ByteBuffer.allocateDirect(newTriangleCoords.length * 4); bb.order(ByteOrder.nativeOrder()); vertexBuffer = bb.asFloatBuffer(); vertexBuffer.put(newTriangleCoords); vertexBuffer.position(0); } public Triangle(){ //init vertex buffer for shape cordinates ByteBuffer bb = ByteBuffer.allocateDirect( //number of cord vals * 4 bytes per float triangleCoords.length * 4); //use hardware's native byte order bb.order(ByteOrder.nativeOrder()); //create floating point buffer vertexBuffer = bb.asFloatBuffer(); //add coords to floatbuffer vertexBuffer.put(triangleCoords); //set buffer to read first coord vertexBuffer.position(0); int vertexShader = MyGL20Renderer.loadShader(GLES20.GL_VERTEX_SHADER, vertexShaderCode); int fragmentShader = MyGL20Renderer.loadShader(GLES20.GL_FRAGMENT_SHADER, fragmentShaderCode); //creates program for the triangle to go in., mProgram = GLES20.glCreateProgram(); GLES20.glAttachShader(mProgram, vertexShader); GLES20.glAttachShader(mProgram, fragmentShader); GLES20.glLinkProgram(mProgram); } } </code></pre> <p>I've already tested this code vs the original code without the added projection and camera views, and there is no difference between the two. Also, for some reason when I test this on an emulator it doesn't work, but it does work when I test it on an actual android phone (although the projection and camera views still don't work).</p>
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    1. PTQuestion
    1. USNicol Bolas
    1. USJasper Lu
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      1. POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
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      1. VTUpMod
    1. COWas your intention to have `uMVPMatrix` do the transformation, because it's not used (or even included) in your vertex shader. Seems like you might want to include that when you set `gl_Position`.
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      1. POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
      1. USradical7
    2. COYeah that's it...should I learn how the shader code works, or should I continue to recycle google's code for now?
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      1. POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
      1. USJasper Lu
    3. COWell, knowing what you're doing never hurts, so I'd recommend at least knowing what the code you're integrating into project does as a good start. Knowing how OpenGL shaders work will help when you want to do something a bit different.
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      1. POTrying to get Projection and Camera View for Android to work - after applying the two views, nothing has changed at all
      1. USradical7
 

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