void TessellationSampleApp::createIcosahedron()
{
const int faces[] = {
2, 1, 0,
3, 2, 0,
4, 3, 0,
5, 4, 0,
1, 5, 0,
11, 6, 7,
11, 7, 8,
11, 8, 9,
11, 9, 10,
11, 10, 6,
1, 2, 6,
2, 3, 7,
3, 4, 8,
4, 5, 9,
5, 1, 10,
2, 7, 6,
3, 8, 7,
4, 9, 8,
5, 10, 9,
1, 6, 10
};
const float verts[] = {
0.000f, 0.000f, 1.000f,
0.894f, 0.000f, 0.447f,
0.276f, 0.851f, 0.447f,
-0.724f, 0.526f, 0.447f,
-0.724f, -0.526f, 0.447f,
0.276f, -0.851f, 0.447f,
0.724f, 0.526f, -0.447f,
-0.276f, 0.851f, -0.447f,
-0.894f, 0.000f, -0.447f,
-0.276f, -0.851f, -0.447f,
0.724f, -0.526f, -0.447f,
0.000f, 0.000f, -1.000f
};
mIndexCount = sizeof(faces) / sizeof(faces[0]);
vertexArrayObject->bind();
// Create the VBO for positions:
GLsizei stride = 3 * sizeof(float);
vertexBufferObject->bind();
vertexBufferObject->bufferData(sizeof(verts), verts, GL_STATIC_DRAW);
gl::enableVertexAttribArray( (GLuint)mPositionIndex );
gl::vertexAttribPointer( (GLuint)mPositionIndex, 3, GL_FLOAT, GL_FALSE, stride, 0 );
// Create the VBO for indices:
indexBufferObject->bind();
indexBufferObject->bufferData( sizeof(faces), faces, GL_STATIC_DRAW );
}
void TransformFeedbackClothSimulationApp::loadBuffers()
{
int n = 0;
array<vec4, POINTS_TOTAL> positions;
array<vec3, POINTS_TOTAL> velocities;
array<ivec4, POINTS_TOTAL> connections;
// We set all connections to -1, because these will only be updated
// if there are connection indices. Explanation below.
connections.fill( ivec4( -1 ) );
for( int j = 0; j < POINTS_Y; j++ ) {
float fj = (float)j / (float)POINTS_Y;
for( int i = 0; i < POINTS_X; i++ ) {
float fi = (float)i / (float)POINTS_X;
// This fills the position buffer data, basically makes a grid
positions[n] = vec4((fi - 0.5f) * (float)POINTS_X, // x coordinate
(fj - 0.5f) * (float)POINTS_Y, // y coordinate
0.6f * sinf(fi) * cosf(fj), // z coordinate
1.0f); // homogenous coordinate or w
// This allows us to figure out the indices of the four points
// surrounding the current point. This will be used to index
// into the texture buffer.
if( j != (POINTS_Y - 1) ) { // if it's not one of the top row, don't move
if( i != 0 )
connections[n][0] = n - 1;
if( j != 0 )
connections[n][1] = n - POINTS_X;
if( i != (POINTS_X - 1) )
connections[n][2] = n + 1;
if( j != (POINTS_Y - 1) )
connections[n][3] = n + POINTS_X;
}
n++;
}
}
// Create the Position Buffer with the intial position data
mPositions[0] = gl::Vbo::create( GL_ARRAY_BUFFER, positions.size() * sizeof(vec4), positions.data(), GL_STATIC_DRAW );
// Create another Position Buffer that is null, for ping-ponging
mPositions[1] = gl::Vbo::create( GL_ARRAY_BUFFER, positions.size() * sizeof(vec4), nullptr, GL_STATIC_DRAW );
// Create the Velocity Buffer with the intial velocity data
mVelocities[0] = gl::Vbo::create( GL_ARRAY_BUFFER, velocities.size() * sizeof(vec3), velocities.data(), GL_STATIC_DRAW );
// Create another Velocity Buffer that is null, for ping-ponging
mVelocities[1] = gl::Vbo::create( GL_ARRAY_BUFFER, velocities.size() * sizeof(vec3), nullptr, GL_STATIC_DRAW );
// Create Connection Buffer to index into the Texture Buffer
mConnections = gl::Vbo::create( GL_ARRAY_BUFFER, connections.size() * sizeof(ivec4), connections.data(), GL_STATIC_DRAW );
for( int i = 0; i < 2; i++ ) {
// Initialize the Vao's holding the info for each buffer
mVaos[i] = gl::Vao::create();
// Bind the vao to capture index data for the glsl
mVaos[i]->bind();
mPositions[i]->bind();
gl::vertexAttribPointer( POSITION_INDEX, 4, GL_FLOAT, GL_FALSE, 0, NULL );
gl::enableVertexAttribArray( POSITION_INDEX );
mVelocities[i]->bind();
gl::vertexAttribPointer( VELOCITY_INDEX, 3, GL_FLOAT, GL_FALSE, 0, NULL );
gl::enableVertexAttribArray( VELOCITY_INDEX );
mConnections->bind();
gl::vertexAttribIPointer( CONNECTION_INDEX, 4, GL_INT, 0, NULL );
gl::enableVertexAttribArray( CONNECTION_INDEX );
// Create a TransformFeedbackObj, which is similar to Vao
// It's used to capture the output of a glsl and uses the
// index of the feedback's varying variable names.
mFeedbackObjs[i] = gl::TransformFeedbackObj::create();
// Bind the TransformFeedbackObj and bind each corresponding buffer
// to it's index.
mFeedbackObjs[i]->bind();
gl::bindBufferBase( GL_TRANSFORM_FEEDBACK_BUFFER, POSITION_INDEX, mPositions[i] );
gl::bindBufferBase( GL_TRANSFORM_FEEDBACK_BUFFER, VELOCITY_INDEX, mVelocities[i] );
mFeedbackObjs[i]->unbind();
// Create Texture buffers to gain access to the lookup tables for
// calculations in the update shader
mPosBufferTextures[i] = gl::BufferTexture::create( mPositions[i], GL_RGBA32F );
}
// Create an element buffer to draw the lines (connections) between the points
array<uint32_t, CONNECTIONS_TOTAL*2> lineIndices;
uint32_t * e = lineIndices.data();
for( int j = 0; j < POINTS_Y; j++ ) {
for( int i = 0; i < POINTS_X - 1; i++ ) {
*e++ = i + j * POINTS_X;
*e++ = 1 + i + j * POINTS_Y;
}
}
for( int i = 0; i < POINTS_X; i++ ) {
for( int j = 0; j < POINTS_Y - 1; j++ ) {
*e++ = i + j * POINTS_X;
*e++ = POINTS_X + i + j * POINTS_X;
}
}
mLineIndices = lineIndices.size();
mLineElementBuffer = gl::Vbo::create( GL_ELEMENT_ARRAY_BUFFER, lineIndices.size() * sizeof(uint32_t), lineIndices.data(), GL_STATIC_DRAW );
}