drawing one centered quad

assets/shaders/fragment.glsl

@@ -1,8 +1,7 @@
 
-varying vec2 tex_coord_i;
+varying vec2 pos_2d_i;
-uniform sampler2D tex;
 
 void main()
 {
-    gl_FragColor = texture2D(tex, tex_coord_i);
+    gl_FragColor = vec4(0, 0.3, 1, 1);
 }

assets/shaders/vertex.glsl

@@ -1,12 +1,15 @@
 
 uniform mat4 projection;
 uniform mat4 modelview;
-attribute vec3 pos;
+uniform vec2 offset;
-attribute vec2 tex_coord;
+
-varying vec2 tex_coord_i;
+attribute vec2 pos;
+
+varying vec2 pos_2d_i;
 
 void main()
 {
-    gl_Position = projection * modelview * vec4(pos, 1);
+    gl_Position = projection *
-    tex_coord_i = tex_coord;
+        (modelview * vec4(pos, 0, 1) + vec4(offset, 0, 1));
+    pos_2d_i = pos + offset;
 }

src/com/homelinux/holtrop/opengltest/MyRenderer.java

@@ -34,8 +34,9 @@ public class MyRenderer implements GLSurfaceView.Renderer
     private int m_width;
     private int m_height;
     private float m_aspect = 1.0f;
-    private float m_x = 0.0f;
+    private final int GRID_WIDTH = 16;
-    private float m_y = 0.0f;
+    private final int GRID_HEIGHT = 9;
+    private float[][] m_tiles = new float[GRID_WIDTH][GRID_HEIGHT];
 
     public MyRenderer(AssetManager am, Resources resources)
     {
@@ -93,10 +94,10 @@ public class MyRenderer implements GLSurfaceView.Renderer
     public void onSurfaceCreated(GL10 unused, EGLConfig config)
     {
         final float attribs[] = {
-            1, 1, 0,    1, 1,
+            1, 1,
-            -1, 1, 0,   0, 1,
+            -1, 1,
-            -1, -1, 0,  0, 0,
+            -1, -1,
-            1, -1, 0,   1, 0,
+            1, -1
         };
         checkGLError("onSurfaceCreated");
         ByteBuffer bb = ByteBuffer.allocateDirect(attribs.length * 4);
@@ -122,6 +123,7 @@ public class MyRenderer implements GLSurfaceView.Renderer
             Log.e(DBGTAG, "Program log: " + info_log);
         }
 
+/*
         Bitmap texture = BitmapFactory.decodeResource(m_resources,
                 R.drawable.texture);
         int[] textures = new int[1];
@@ -139,6 +141,7 @@ public class MyRenderer implements GLSurfaceView.Renderer
         GLES20.glGenerateMipmap(GLES20.GL_TEXTURE_2D);
         checkGLError("glGenerateMipmap");
         texture.recycle();
+*/
 
         GLES20.glClearColor(1.0f, 0.6f, 0.1f, 1.0f);
     }
@@ -147,32 +150,22 @@ public class MyRenderer implements GLSurfaceView.Renderer
     {
         GLES20.glClear(GLES20.GL_COLOR_BUFFER_BIT);
 
-        long time = SystemClock.uptimeMillis() % 4000L;
-        float angle = 0.090f * ((int) time);
         Matrix.setIdentityM(m_modelview, 0);
-        Matrix.translateM(m_modelview, 0, m_x, m_y, 0);
+        Matrix.translateM(m_modelview, 0, 0, 0, 0);
-        Matrix.rotateM(m_modelview, 0, angle, 0, 0, 1);
-        Matrix.scaleM(m_modelview, 0, 0.4f, 0.4f, 0.4f);
         GLES20.glUniformMatrix4fv(
                 GLES20.glGetUniformLocation(m_program, "modelview"),
                 1, false, m_modelview, 0);
         int attr_pos = GLES20.glGetAttribLocation(m_program, "pos");
-        int attr_tex_coord = GLES20.glGetAttribLocation(m_program, "tex_coord");
         checkGLError("glGetAttribLocation");
         GLES20.glEnableVertexAttribArray(attr_pos);
-        GLES20.glEnableVertexAttribArray(attr_tex_coord);
         checkGLError("glEnableVertexAttribArray");
         m_quad_attrib_buffer.position(0);
-        GLES20.glVertexAttribPointer(attr_pos, 3, GLES20.GL_FLOAT, false,
+        GLES20.glVertexAttribPointer(attr_pos, 2, GLES20.GL_FLOAT, false,
-                5 * 4, m_quad_attrib_buffer);
+                2 * 4, m_quad_attrib_buffer);
-        m_quad_attrib_buffer.position(3);
-        GLES20.glVertexAttribPointer(attr_tex_coord, 2, GLES20.GL_FLOAT, false,
-                5 * 4, m_quad_attrib_buffer);
         checkGLError("glVertexAttribPointer");
         GLES20.glDrawArrays(GLES20.GL_TRIANGLE_FAN, 0, 4);
         checkGLError("glDrawArrays");
         GLES20.glDisableVertexAttribArray(attr_pos);
-        GLES20.glDisableVertexAttribArray(attr_tex_coord);
         checkGLError("glDisableVertexAttribArray");
     }
 
@@ -185,8 +178,9 @@ public class MyRenderer implements GLSurfaceView.Renderer
         GLES20.glViewport(0, 0, width, height);
 
         Matrix.orthoM(m_proj_matrix, 0,
-                -m_aspect, m_aspect,
+                -GRID_WIDTH / 2.0f, GRID_WIDTH / 2.0f,
-                -1, 1, 1, -1);
+                -GRID_HEIGHT / 2.0f, GRID_HEIGHT / 2.0f,
+                1, -1);
 
         GLES20.glUseProgram(m_program);
 
@@ -200,12 +194,6 @@ public class MyRenderer implements GLSurfaceView.Renderer
         if (e.getAction() == MotionEvent.ACTION_DOWN ||
             e.getAction() == MotionEvent.ACTION_MOVE)
         {
-            float x = m_aspect * ((e.getX() / (float) m_width) * 2.0f - 1.0f);
-            float y = -((e.getY() / (float) m_height) * 2.0f - 1.0f);
-
-            m_x = x;
-            m_y = y;
-
             return true;
         }