Jump to content
  • Advertisement
Sign in to follow this  

OpenGL ES Texturing

This topic is 2032 days old which is more than the 365 day threshold we allow for new replies. Please post a new topic.

If you intended to correct an error in the post then please contact us.

Recommended Posts

I noticed some strange behavior when trying to texture in OpenGL-ES for Android. I've followed some tutorials and applied the implementations to my code. Where things differ is where I encapsulate the drawing code in an entity class, and point the code to my existing (but altered to fit) shader. This is the texture that I'm trying to draw:




Just needed something with vertical and horizontal lines. Here's how it is drawn:



It looks to be the texture coordinates, But nothing seems to happen when I switch to trianglefan either.

Below is the full Entity class:

Additionally, I call the constructors in the render class as such:

    public void draw(float[] mMVPMatrix) {
        // Add program to OpenGL environment

        // get handle to vertex shader's vPosition member
        mPositionHandle = GLES20.glGetAttribLocation(mProgram, "vPosition");

        // Enable a handle to the triangle vertices

        // Prepare the triangle coordinate data
                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");
        //Texture start
        mTextureUniformHandle = GLES20.glGetUniformLocation(mProgram, "u_Texture");
        mTextureCoordinateHandle = GLES20.glGetAttribLocation(mProgram, "a_TexCoordinate");
        // Set the active texture unit to texture unit 0.
        // Bind the texture to this unit.
        GLES20.glBindTexture(GLES20.GL_TEXTURE_2D, mTextureDataHandle);
        // Tell the texture uniform sampler to use this texture in the shader by binding to texture unit 0.
        GLES20.glUniform1i(mTextureUniformHandle, 0);
        Matrix.translateM(mMVPMatrix, 0, Tx, Ty, Tz);
        Matrix.scaleM(mMVPMatrix, 0, Sx, Sy, Sz);
        Matrix.rotateM(mMVPMatrix, 0, Rangle, Rx, Ry, Rz);
        // Apply the projection and view transformation
        GLES20.glUniformMatrix4fv(mMVPMatrixHandle, 1, false, mMVPMatrix, 0);

        // Draw the square
                GLES20.GL_TRIANGLES, drawOrder.length,
                GLES20.GL_UNSIGNED_SHORT, drawListBuffer);

        // Disable vertex array

//Render Class
private Entity mSquare;

Class constructor...


mSquare = new Entity (mMVPMatrix, mActivityContext);

And for drawing:

Edited by InfinityMachine

Share this post

Link to post
Share on other sites

It was the glEnableVertexAttribArray for texture coords.  I told him in chat.

Edited by LoneDwarf

Share this post

Link to post
Share on other sites

As LoneDrawf has mentioned … setting up the second vertex attribute is missing. Something like

        GLES20.glVertexAttribPointer(mTextureCoordinateHandle, ...);


BTW: Performance-wise it isn't good to resolve attribute and uniform locations on every draw call.

Share this post

Link to post
Share on other sites

Very true.  I actually keep a bitmask around to represent what is set but if you're starting out I would set it redundantly until you're rock solid.

Share this post

Link to post
Share on other sites
Sign in to follow this  

  • Advertisement

Important Information

By using GameDev.net, you agree to our community Guidelines, Terms of Use, and Privacy Policy.

GameDev.net is your game development community. Create an account for your GameDev Portfolio and participate in the largest developer community in the games industry.

Sign me up!