From bc9f517cb15647d946286c9d0a33ae4cc2e029be Mon Sep 17 00:00:00 2001
From: Hannes Janetzek <hannes.janetzek@gmail.com>
Date: Fri, 1 Feb 2013 12:09:48 +0100
Subject: [PATCH] extend CustomOverlay example to draw a triangle
---
.../renderer/overlays/CustomOverlay.java | 106 +++++++++++++++++-
1 file changed, 103 insertions(+), 3 deletions(-)
diff --git a/src/org/oscim/renderer/overlays/CustomOverlay.java b/src/org/oscim/renderer/overlays/CustomOverlay.java
index 8108776a..b378d64b 100644
--- a/src/org/oscim/renderer/overlays/CustomOverlay.java
+++ b/src/org/oscim/renderer/overlays/CustomOverlay.java
@@ -14,28 +14,128 @@
*/
package org.oscim.renderer.overlays;
+import java.nio.ByteBuffer;
+import java.nio.ByteOrder;
+import java.nio.FloatBuffer;
+
import org.oscim.core.MapPosition;
+import org.oscim.renderer.GLState;
+import org.oscim.utils.GlUtils;
import org.oscim.view.MapView;
+import android.opengl.GLES20;
+import android.opengl.Matrix;
+
+// http://safari.informit.com/9780321563835
+// http://www.opengles-book.com
+
public class CustomOverlay extends RenderOverlay {
+ private int mProgramObject;
+ private int hVertexPosition;
+ private int hMatrixPosition;
+
+ private FloatBuffer mVertices;
+ private final float[] mVerticesData = {
+ 0, 200, 0,
+ -200, -200, 0,
+ 200, -200, 0
+ };
+ private boolean mInitialized;
+
public CustomOverlay(MapView mapView) {
super(mapView);
}
+ // ---------- everything below runs in GLRender Thread ----------
@Override
public void update(MapPosition curPos, boolean positionChanged, boolean tilesChanged) {
- // tell GLRender to call 'compile'
- newData = true;
+ if (!mInitialized) {
+ if (!init())
+ return;
+
+ // tell GLRender to call 'compile' when data has changed
+ newData = true;
+
+ mInitialized = true;
+ }
}
@Override
public void compile() {
+ // modify mVerticesData and put in FloatBuffer
+
+ mVertices.clear();
+ mVertices.put(mVerticesData);
+ mVertices.flip();
+
+ newData = false;
+
// tell GLRender to call 'render'
isReady = true;
}
@Override
- public void render(MapPosition pos, float[] mv, float[] proj) {
+ public void render(MapPosition pos, float[] tmp, float[] proj) {
+
+ // Use the program object
+ GLState.useProgram(mProgramObject);
+
+ GLState.blend(true);
+ GLState.test(false, false);
+
+ // unbind previously bound VBOs
+ GLES20.glBindBuffer(GLES20.GL_ARRAY_BUFFER, 0);
+
+ // Load the vertex data
+ mVertices.position(0);
+ GLES20.glVertexAttribPointer(hVertexPosition, 3, GLES20.GL_FLOAT, false, 0, mVertices);
+ GLState.enableVertexArrays(hVertexPosition, -1);
+
+ // apply view and projection matrices
+ Matrix.multiplyMM(tmp, 0, proj, 0, pos.viewMatrix, 0);
+ GLES20.glUniformMatrix4fv(hMatrixPosition, 1, false, tmp, 0);
+
+ // Draw the triangle
+ GLES20.glDrawArrays(GLES20.GL_TRIANGLES, 0, 3);
+
+ GlUtils.checkGlError("...");
}
+
+ private boolean init() {
+ // Load the vertex/fragment shaders
+ int programObject = GlUtils.createProgram(vShaderStr, fShaderStr);
+
+ if (programObject == 0)
+ return false;
+
+ // Handle for vertex position in shader
+ hVertexPosition = GLES20.glGetAttribLocation(programObject, "a_pos");
+ hMatrixPosition = GLES20.glGetUniformLocation(programObject, "u_mvp");
+
+ // Store the program object
+ mProgramObject = programObject;
+
+ mVertices = ByteBuffer.allocateDirect(mVerticesData.length * 4)
+ .order(ByteOrder.nativeOrder()).asFloatBuffer();
+
+ return true;
+ }
+
+ private final static String vShaderStr =
+ "precision mediump float;"
+ + "uniform mat4 u_mvp;"
+ + "attribute vec4 a_pos;"
+ + "void main()"
+ + "{"
+ + " gl_Position = u_mvp * a_pos;"
+ + "}";
+
+ private final static String fShaderStr =
+ "precision mediump float;"
+ + "void main()"
+ + "{"
+ + " gl_FragColor = vec4 ( 0.0, 0.0, 0.0, 0.7 );"
+ + "}";
+
}