glActiveTexture example c c++ objc java

Name

glActiveTexture - select server-side active texture unit

C Specification

void glActiveTexture(GLenum texture)

Parameters

texture

Specifies which texture unit to make active. The number of texture units is implementation dependent, but must be at least one. texture must be one of GL_TEXTUREi, where 0 ≤ i < GL_MAX_TEXTURE_UNITS, which is an implementation-dependent value. The intial value is GL_TEXTURE0.

Description

glActiveTexture selects which texture unit subsequent texture state calls will affect. The number of texture units an implementation supports is implementation dependent, it must be at least 1.

Errors

GL_INVALID_ENUM is generated if texture is not one of GL_TEXTUREi, where 0 ≤ i < GL_MAX_TEXTURE_UNITS.

Notes

It is always the case that GL_TEXTUREi = GL_TEXTURE0 + i.
A texture unit consists of the texture enable state, texture matrix stack, texture environment and currently bound texture. Modifying any of these states has an effect only on the active texture unit.
Vertex arrays are client-side GL resources, which are selected by the glClientActiveTexture routine.

Associated Gets

glGetInteger with argument GL_MAX_TEXTURE_UNITS

Copyright

Copyright © 2003 Silicon Graphics, Inc.
This document is licensed under the SGI Free Software B License. For details, see http://oss.sgi.com/projects/FreeB/.

See Also

glBindTexture, glClientActiveTexture, glEnable, glGetInteger, glMatrixMode, glMultiTexCoord, glTexEnv

Examples

public class Text3d {

 private IntBuffer   mVertexBuffer;
    private IntBuffer   mColorBuffer;
    private ByteBuffer  mIndexBuffer;
    private FloatBuffer mfTexBuffer;
    private int mTextureID;
   
 public Text3d(){
     int one = 50;
         int vertices[] = {
                 0, one, 0,
                 one, one, 0,
                 0,  0, 0,
                 one,  0, 0,
              
         };
        
         float tex[] = {
           0.0f ,0.0f,
           1.0f,0.0f,
           0.0f ,1.0f,
           1.0f,1.0f,
        
         };
         one = 100000;
         int colors[] = {
           one,    one,    one,  one,
                 one,    one,    one,  one,
                 one,  one,    one,  one,
                 one,  one,    one,  one,
               
         };
         byte indices[] = {
                 0, 1, 2,
                 1, 3, 2,
         };
    
         ByteBuffer vbb = ByteBuffer.allocateDirect(vertices.length*4);
         vbb.order(ByteOrder.nativeOrder());
         mVertexBuffer = vbb.asIntBuffer();
         mVertexBuffer.put(vertices);
         mVertexBuffer.position(0);
        
         ByteBuffer tbb = ByteBuffer.allocateDirect(tex.length*4);
         tbb.order(ByteOrder.nativeOrder());
         mfTexBuffer = tbb.asFloatBuffer();
         mfTexBuffer.put(tex);
         mfTexBuffer.position(0);
         ByteBuffer cbb = ByteBuffer.allocateDirect(colors.length*4);
         cbb.order(ByteOrder.nativeOrder());
         mColorBuffer = cbb.asIntBuffer();
         mColorBuffer.put(colors);
         mColorBuffer.position(0);
         mIndexBuffer = ByteBuffer.allocateDirect(indices.length);
         mIndexBuffer.put(indices);
         mIndexBuffer.position(0);
     
     }


  public void TexCreate(GL10 gl,Context mContext)
  {
   int[] textures = new int[1];
         gl.glGenTextures(1, textures, 0);
         mTextureID = textures[0];
         gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
        
         gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_MIN_FILTER,
                 GL10.GL_NEAREST);
         gl.glTexParameterf(GL10.GL_TEXTURE_2D,
                 GL10.GL_TEXTURE_MAG_FILTER,
                 GL10.GL_LINEAR);
         gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_S,
                 GL10.GL_CLAMP_TO_EDGE);
         gl.glTexParameterf(GL10.GL_TEXTURE_2D, GL10.GL_TEXTURE_WRAP_T,
                 GL10.GL_CLAMP_TO_EDGE);
         gl.glTexEnvf(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
                 GL10.GL_REPLACE);
      
        
      Bitmap mBitmap;
     
      Canvas mCanvas;
     
      Bitmap.Config config =   Bitmap.Config.ARGB_8888;
     
      mBitmap = Bitmap.createBitmap(128, 128, config);
         mCanvas = new Canvas(mBitmap);
         mBitmap.eraseColor(0);
        
         mCanvas.drawColor(0x00ffffff);
        
         Paint Pnt = new Paint();
         Pnt.setColor(0xff00ff00);
         Pnt.setTextSize(128);
         Pnt.setAntiAlias(false);
         Pnt.setTextScaleX(1);
        
         mCanvas.drawText("B", 0, 128, Pnt);
         
         GLUtils.texImage2D(GL10.GL_TEXTURE_2D, 0, mBitmap, 0);
        
         mBitmap.recycle();   
   }

     public void draw(GL10 gl)
     {
    
         gl.glFrontFace(GL10.GL_CW);
         gl.glEnable(GL10.GL_TEXTURE_2D);
         gl.glColor4f(1f, 1f, 1f, 1f);
         gl.glTexEnvx(GL10.GL_TEXTURE_ENV, GL10.GL_TEXTURE_ENV_MODE,
                 GL10.GL_MODULATE);
        
         gl.glBindTexture(GL10.GL_TEXTURE_2D, mTextureID);
        
         gl.glEnableClientState(GL10.GL_VERTEX_ARRAY);
         gl.glEnableClientState(GL10.GL_TEXTURE_COORD_ARRAY);
         gl.glActiveTexture(GL10.GL_TEXTURE0);
       
         gl.glTexCoordPointer(2, GL10.GL_FLOAT, 0, mfTexBuffer);
         gl.glVertexPointer(3, GL10.GL_FIXED, 0, mVertexBuffer);
         gl.glColorPointer(4, GL10.GL_FIXED, 0, mColorBuffer);
         gl.glDrawElements(GL10.GL_TRIANGLES, 6, GL10.GL_UNSIGNED_BYTE, mIndexBuffer);
     }
}