Example usage for org.lwjgl.opengl ARBInstancedArrays glVertexAttribDivisorARB

Introduction

In this page you can find the example usage for org.lwjgl.opengl ARBInstancedArrays glVertexAttribDivisorARB.

Prototype

public static native void glVertexAttribDivisorARB(@NativeType("GLuint") int index,
        @NativeType("GLuint") int divisor);

Source Link

Document

Modifies the rate at which generic vertex attributes advance when rendering multiple instances of primitives in a single draw call.

Usage

From source file:org.lwjgl.demo.opengl.instancing.GrassDemo.java

License:Open Source License

private void generateGrassPatchVao() {
    int n = NUM_FACES_PER_PATCH;
    // Generate the model attributes of a single grass patch
    FloatBuffer fb = BufferUtils.createFloatBuffer(NUM_FACES_PER_PATCH * 6 * (3 + 2));
    for (int i = 0; i < n; i++) {
        float x0 = (float) (Math.cos((double) i / n * Math.PI)) * 0.5f;
        float z0 = (float) (Math.sin((double) i / n * Math.PI)) * 0.5f;
        float x1 = (float) (Math.cos((double) i / n * Math.PI + Math.PI)) * 0.5f;
        float z1 = (float) (Math.sin((double) i / n * Math.PI + Math.PI)) * 0.5f;
        fb.put(x0).put(0.0f).put(z0).put(0).put(1);
        fb.put(x1).put(0.0f).put(z1).put(1).put(1);
        fb.put(x1).put(1.0f).put(z1).put(1).put(0);
        fb.put(x1).put(1.0f).put(z1).put(1).put(0);
        fb.put(x0).put(1.0f).put(z0).put(0).put(0);
        fb.put(x0).put(0.0f).put(z0).put(0).put(1);
    }//  w  w w .j a v a  2  s.c o  m
    fb.flip();
    // Generate the world-space positions of each patch
    final FloatBuffer pb = BufferUtils.createFloatBuffer(NUM_GRASS_PATCHES * 4);
    new BestCandidateSampling.Quad(0L, NUM_GRASS_PATCHES, 20, new Callback2d() {
        final Random rnd = new Random(0L);
        int index = 0;

        public void onNewSample(float x, float y) {
            float px = x * MEADOW_SIZE;
            float py = y * MEADOW_SIZE;
            grassPatchPositions[index++] = new Vector2f(px, py);
            pb.put(x * MEADOW_SIZE).put(y * MEADOW_SIZE).put(rnd.nextFloat() * 0.2f + 0.9f)
                    .put((SimplexNoise.noise(x * 2.342f, y * 2.0352f) + 1.0f) * 0.5f);
        }
    });
    pb.flip();
    // Generate the random rotations for each grass patch
    FloatBuffer rb = BufferUtils.createFloatBuffer(NUM_GRASS_PATCHES * 4);
    Random rnd = new Random();
    Matrix3x2f m = new Matrix3x2f();
    for (int i = 0; i < NUM_GRASS_PATCHES; i++) {
        float angle = 2.0f * (float) Math.PI * rnd.nextFloat();
        m.rotation(angle);
        rb.put(m.m00).put(m.m01).put(m.m10).put(m.m11);
    }
    rb.flip();
    grassVao = ARBVertexArrayObject.glGenVertexArrays();
    ARBVertexArrayObject.glBindVertexArray(grassVao);
    int modelBuffer = glGenBuffers();
    int grassBladesPositionsVbo = glGenBuffers();
    grassDisplacementVbo = glGenBuffers();
    int grassRotationVbo = glGenBuffers();
    glBindBuffer(GL_ARRAY_BUFFER, modelBuffer);
    glBufferData(GL_ARRAY_BUFFER, fb, GL_STATIC_DRAW);
    glVertexAttribPointer(grassPositionAttribute, 3, GL_FLOAT, false, 4 * (3 + 2), 0L);
    glVertexAttribPointer(grassTexCoordAttribute, 2, GL_FLOAT, false, 4 * (3 + 2), 4 * 3L);
    glEnableVertexAttribArray(grassPositionAttribute);
    glEnableVertexAttribArray(grassTexCoordAttribute);
    glBindBuffer(GL_ARRAY_BUFFER, grassBladesPositionsVbo);
    glBufferData(GL_ARRAY_BUFFER, pb, GL_STATIC_DRAW);
    glVertexAttribPointer(grassWorldPositionAttribute, 4, GL_FLOAT, false, 0, 0L);
    ARBInstancedArrays.glVertexAttribDivisorARB(grassWorldPositionAttribute, 1);
    glEnableVertexAttribArray(grassWorldPositionAttribute);
    glBindBuffer(GL_ARRAY_BUFFER, grassDisplacementVbo);
    glBufferData(GL_ARRAY_BUFFER, 4 * 2 * NUM_GRASS_PATCHES, GL_STATIC_DRAW);
    glVertexAttribPointer(grassDisplacementAttribute, 2, GL_FLOAT, false, 0, 0L);
    ARBInstancedArrays.glVertexAttribDivisorARB(grassDisplacementAttribute, 1);
    glEnableVertexAttribArray(grassDisplacementAttribute);
    glBindBuffer(GL_ARRAY_BUFFER, grassRotationVbo);
    glBufferData(GL_ARRAY_BUFFER, rb, GL_STATIC_DRAW);
    glVertexAttribPointer(grassRotationAttribute, 4, GL_FLOAT, false, 0, 0L);
    ARBInstancedArrays.glVertexAttribDivisorARB(grassRotationAttribute, 1);
    glEnableVertexAttribArray(grassRotationAttribute);
    glBindBuffer(GL_ARRAY_BUFFER, 0);
    ARBVertexArrayObject.glBindVertexArray(0);
}

---