CODEWITHSUNDEEP
javaopenglpngtextureslwjgl
gamesaucer
gamesaucer

Reputation: 133

Drawing textured quads OpenGL not working

I am trying to render a group of textured quads.

I can get colored quads to render, but not textured ones (screen comes up empty.)

I am using LWJGL and PNGDecoder.

Code for initializing my OGL:

GL11.glMatrixMode(GL11.GL_PROJECTION);
GL11.glLoadIdentity();
GL11.glOrtho(0, 800, 0, 600, 1, -1);
GL11.glMatrixMode(GL11.GL_MODELVIEW);
GL11.glEnable(GL11.GL_TEXTURE_2D);

Code for decoding my image:

ByteBuffer buffer = null;
InputStream in = ClassLoader.getSystemResourceAsStream(filename);
try {
    buffer = decodeStreamToBuffer(in);
} finally {
    in.close();
}
return buffer;

My decodeStreamToBuffer(InputStream in):

PNGDecoder decoder;
ByteBuffer buf = null;
try {
    decoder = new PNGDecoder(in);

    buf = ByteBuffer.allocateDirect(4*decoder.getWidth()*decoder.getHeight());
    decoder.decode(buf, decoder.getWidth()*4, Format.RGBA);
    buf.flip();
} catch (Exception e) {
    e.printStackTrace();
}

return buf;

My rendering code:

    GL11.glClear(GL11.GL_COLOR_BUFFER_BIT | GL11.GL_DEPTH_BUFFER_BIT);
    GL11.glColor3f(0.5f, 0.5f, 1.0f); //Still there to test color quads.

    // draw quad
    GL11.glPushMatrix();
        GL11.glTranslatef(screencenter.getX(), screencenter.getY(), 0);
        GL11.glScalef(1f, 0.5f, 1f);
        GL11.glRotatef(camRotation, 0f, 0f, 1f);
        GL11.glTranslatef(-screencenter.getX(), -screencenter.getY(), 0);

        GL11.glBindTexture(GL11.GL_TEXTURE_2D, texture);
        GL11.glBegin(GL11.GL_TEXTURE_2D);

            GL11.glTexCoord2f(0.0f, 0.0f);
            GL11.glVertex2f(0, 0);

            GL11.glTexCoord2f(1.0f, 0.0f);
            GL11.glVertex2f(32, 0);

            GL11.glTexCoord2f(1.0f, 1.0f);
            GL11.glVertex2f(32, 32);

            GL11.glTexCoord2f(0.0f, 1.0f);
            GL11.glVertex2f(0, 32);

        GL11.glEnd();

    GL11.glPopMatrix();

When I leave the texture binding out and change the GL_TEXTURE_2D to GL_MODELVIEW it all works... but with color instead of a texture. Am I making a noob mistake here?

Upvotes: 1

Views: 1572

Answers (1)

vallentin
vallentin

Reputation: 26245

This is wrong GL11.glBegin(GL11.GL_TEXTURE_2D);

The glBegin method an primitive mode GLenum.

Thereby you either use:

  • GL_POINTS
  • GL_LINES
  • GL_LINE_STRIP
  • GL_LINE_LOOP
  • GL_TRIANGLES
  • GL_TRIANGLE_STRIP
  • GL_TRIANGLE_FAN
  • GL_QUADS
  • GL_QUAD_STRIP
  • GL_POLYGON

The mode you use specify what you are rendering. In your case you would code GL_QUADS So to fix your code you need to replace GL11.glBegin(GL11.GL_TEXTURE_2D); with GL11.glBegin(GL11.GL_QUADS);.

Extra

Also take in mind that the glVertex, glNormal, glTexCoord, etc. Methods are deprecated and should not be used. You are suppose to use VBOs and Shaders. Though if you are learning OpenGL then keep using the deprecated methods since they are good and easy to use when learning!

Upvotes: 2

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