CODEWITHSUNDEEP
javaopengllwjgl
Joehot200
Joehot200

Reputation: 1090

How can I draw a texture on an OpenGL/LWJGL display list?

I have got a display list. (Yes, i get the fact that they are depricated already. I have reasons for using them.)

How can I display textures on the display list?

While I would prefer to have different textures at different locations, actually HAVING A TEXTURE on the display list would be a great start and for a game in closed alpha testing might actually be good enough until a better solution was found.

try {
        // Load the heightmap-image from its resource file
        System.out.println("Path: " + new File(System.getProperty("user.dir") + "/res/heightmap.bmp").getAbsolutePath());
        BufferedImage heightmapImage = ImageIO.read(new File(
                System.getProperty("user.dir") + "/res/heightmap.bmp"));

        width = heightmapImage.getWidth();
        height = heightmapImage.getHeight();
        BufferedImage heightmapColour = ImageIO.read(new File(System.getProperty("user.dir") +
                "/res/colours.bmp"));
        data = new float[heightmapImage.getWidth()][heightmapImage
                .getHeight()];

        red = new float[heightmapColour.getWidth()][heightmapColour
                .getHeight()];
        blue = new float[heightmapColour.getWidth()][heightmapColour
                .getHeight()];
        green = new float[heightmapColour.getWidth()][heightmapColour
                .getHeight()];
        Color colour;
        Color colours;
        PNGDecoder decoder = new PNGDecoder(heightmapLookupInputStream);
        ByteBuffer buffer = BufferUtils.createByteBuffer(4
                * decoder.getWidth() * decoder.getHeight());
        decoder.decode(buffer, decoder.getWidth() * 4,
                PNGDecoder.Format.RGBA);
        buffer.flip();
        heightmapLookupInputStream.close();
        lookupTexture = glGenTextures();
        glBindTexture(GL_TEXTURE_2D, lookupTexture);
        // Hand the texture data to OpenGL
        glTexImage2D(GL_TEXTURE_2D, 0, GL_RGBA, decoder.getWidth(),
                decoder.getHeight(), 0, GL_RGBA, GL_UNSIGNED_BYTE, buffer);
    } catch (IOException e) {
        e.printStackTrace();

    }
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
    glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
    heightmapDisplayList = glGenLists(1);
    glNewList(heightmapDisplayList, GL_COMPILE);

    for (int z = 0; z < data.length - 1; z++) {
        // Render a triangle strip for each 'strip'.
        glBegin(GL_TRIANGLE_STRIP);
        for (int x = 0; x < data[z].length; x++) {
            // Take a vertex from the current strip
            if (((blue[z][x] / 255) < 0.4))
                glColor4f((red[z][x] / 255) / 2
                        + (float) (Math.random() / 10), (green[z][x] / 255)
                        / 2 + (float) (Math.random() / 10),
                        (blue[z][x] / 255) / 2
                                + (float) (Math.random() / 10), 1);
            else {
                glColor4f((red[z][x] / 255) / 2
                        + (float) (Math.random() / 10), (green[z][x] / 255)
                        / 2 + (float) (Math.random() / 10),
                        (blue[z][x] / 255) / 2
                                + (float) (Math.random() / 10), 1);
            }
            if (data[z][x] >= WATER_LEVEL -10){

            glVertex3f(x, data[z][x], z);
            glVertex3f(x, data[z + 1][x], z + 1);

            }

        }
        glEnd();
    }
    glEndList();

If you can't read my poorly formatted code, then I am using a GL_TRIANGLE_STRIP to render stuff from a .bmp file, if it makes any difference.

Upvotes: 0

Views: 257

Answers (1)

genpfault
genpfault

Reputation: 52157

  1. Use GL_NEAREST/GL_LINEAR for GL_TEXTURE_MIN_FILTER. Or provide some mipmaps. Failure to do one of those two will result in an incomplete texture.
  2. glEnable(GL_TEXTURE_2D). Without that OpenGL will continue to ignore any bound textures.
  3. Provide some texture coordinates before each glVertex() call, perhaps via glTexCoord().

Upvotes: 1

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