void initHeightMap ()
{
num_hm_elements = hm.sizeOfTriangleVertices()*2;
vec4 hm_elements [num_hm_elements];
hm.flattenTriangles (hm_elements);
// num_hm_elements = hm.getSize () * 2;
// vec4 hm_elements [num_hm_elements];
// hm.flatten (hm_elements);
// indices = new unsigned [ hm.sizeOfTriStripIndices () ];
// hm.flattenTriStripIndices (indices);
glGenVertexArrays(1, &hm_vao);
glBindVertexArray(hm_vao);
GLuint buffer;
glGenBuffers (1, &buffer);
glBindBuffer (GL_ARRAY_BUFFER, buffer);
glBufferData (GL_ARRAY_BUFFER, num_hm_elements*sizeof(vec4), hm_elements, GL_STATIC_DRAW);
glEnableVertexAttribArray ( vPosition );
glVertexAttribPointer ( vPosition, 4, GL_FLOAT, GL_FALSE, sizeof(vec4)*2, BUFFER_OFFSET(0) );
glEnableVertexAttribArray( vColor );
glVertexAttribPointer ( vColor, 4, GL_FLOAT, GL_FALSE, sizeof(vec4)*2, BUFFER_OFFSET(sizeof (vec4)));
}
void displayTerrain ()
{
glUniform1i (solidColor, 0);
glUniformMatrix4fv (vMvp, 1, GL_TRUE, projectionView);
glBindVertexArray( hm_vao );
glPrimitiveRestartIndex (PRIMITIVE_RESTART);
glDrawArrays( GL_TRIANGLES, 0, hm.sizeOfTriangleVertices () );
//glDrawArrays( GL_LINE_STRIP, 0, hm.getSize () );
//glDrawElements ( GL_TRIANGLE_STRIP, hm.sizeOfTriStripIndices (), GL_UNSIGNED_INT, indices);
}