func prepareScene() {
theTriangleBuf = glh.NewMeshBuffer(
glh.RenderArrays,
glh.NewIndexAttr(1, gl.UNSIGNED_INT, gl.STATIC_DRAW),
glh.NewPositionAttr(3, gl.FLOAT, gl.STATIC_DRAW),
)
theTriangleBuf.Add(triangleIdx, triangleVertex)
}
// Create the glh.MeshBufer
func createBuffer() *glh.MeshBuffer {
if len(scene.Mesh[0].Colors) == 0 {
// just add some colors to it.
assimp.RandomColor(scene.Mesh[0])
}
fmesh := assimp.NewFlatMesh(scene.Mesh[0])
println("FMesh vertex count: ", len(fmesh.Vertex))
var idxAttr *glh.Attr
switch sz := len(fmesh.Index); {
case sz < int(assimp.ByteSize):
idxAttr = glh.NewIndexAttr(1, gl.UNSIGNED_BYTE, gl.STATIC_DRAW)
case sz < int(assimp.ShortSize):
idxAttr = glh.NewIndexAttr(1, gl.UNSIGNED_SHORT, gl.STATIC_DRAW)
default:
idxAttr = glh.NewIndexAttr(1, gl.UNSIGNED_INT, gl.STATIC_DRAW)
}
idxAttr = glh.NewIndexAttr(1, gl.UNSIGNED_INT, gl.STATIC_DRAW)
// Create a mesh buffer with the given attributes.
mb := glh.NewMeshBuffer(
glh.RenderBuffered,
// Indices.
idxAttr,
// Vertex positions have 3 components (x, y, z).
glh.NewPositionAttr(3, gl.FLOAT, gl.STATIC_DRAW),
// Colors have 4 components (r, g, b, a).
glh.NewColorAttr(4, gl.FLOAT, gl.STATIC_DRAW),
)
// Add the mesh to the buffer.
mb.Add(fmesh.Index, fmesh.Vertex, fmesh.Color)
return mb
}
func createMeshBuffer() *glh.MeshBuffer {
mb := glh.NewMeshBuffer(
glh.RenderBuffered,
glh.NewIndexAttr(1, gl.UNSIGNED_SHORT, gl.STATIC_DRAW),
// 2 INTEGER values should be enough, but
// just to keep things simpler
// let's work with 3d vertex instead of 2d
// it's easier to find help that way
glh.NewPositionAttr(3, gl.FLOAT, gl.STATIC_DRAW),
// At this moment, let's use colors instead of textures
glh.NewColorAttr(3, gl.UNSIGNED_BYTE, gl.DYNAMIC_DRAW))
return mb
}
// createBuffer creates a mesh buffer and fills it with data.
func createBuffer() *glh.MeshBuffer {
// Create a mesh buffer with the given attributes.
mb := glh.NewMeshBuffer(
glh.RenderBuffered,
// 1 index per vertex.
glh.NewIndexAttr(1, gl.UNSIGNED_SHORT, gl.STATIC_DRAW),
// Vertex positions have 2 components (x, y).
// These will never be changing, so mark them as static.
glh.NewPositionAttr(2, gl.INT, gl.STATIC_DRAW),
// Colors have 3 components (r, g, b).
// These will be changing, so make them dynamic.
glh.NewColorAttr(3, gl.UNSIGNED_BYTE, gl.DYNAMIC_DRAW),
)
// Define components for a simple, coloured quad.
idx := []uint16{0, 1, 2, 3}
pos := []int32{0, 0, 0, 0, 0, 0, 0, 0}
clr := []uint8{0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0, 0}
for y := 0; y < Rows; y++ {
py := int32(CellHeight * y)
pos[1] = py + 1
pos[3] = py + 1
pos[5] = py + CellHeight
pos[7] = py + CellHeight
for x := 0; x < Cols; x++ {
px := int32(CellWidth * x)
pos[0] = px + 1
pos[2] = px + CellWidth
pos[4] = px + CellWidth
pos[6] = px + 1
palette := colors[rng.Int31n(6)]
setColor(clr, palette[0], palette[1], palette[2])
mb.Add(idx, pos, clr)
}
}
return mb
}
func createBuffer() *glh.MeshBuffer {
// We create as few vertices as possible.
// Manually building a cube would require 24 vertices. Many of which
// are duplicates. All we have to define here, is the 8 unique ones
// necessary to construct each face of the cube.
pos := []float32{
1, 1, -1, -1, 1, -1, -1, 1, 1, 1, 1, 1,
1, -1, 1, -1, -1, 1, -1, -1, -1, 1, -1, -1,
}
a := float32(0.02)
// Each vertex comes with its own colour.
clr := []float32{
1, 0, 0, a, 0, 1, 0, a, 0, 0, 1, a, 1, 0, 1, a,
1, 1, 0, a, 0, 1, 1, a, 1, 1, 1, a, 0, 0, 0, a,
}
// These are the indices into the position and color lists.
// They tell the GPU which position/color pair to use in order to construct
// the whole cube. As can be seen, all elements are repeated multiple
// times to create the correct layout. For large meshes with many duplicate
// vertices, this can save a sizable amount of storage space.
idx := []byte{
0, 1, 2, 3, 4, 5, 6, 7, 3, 2, 5, 4,
7, 6, 1, 0, 2, 1, 6, 5, 0, 3, 4, 7,
}
// Create a mesh buffer with the given attributes.
mb := glh.NewMeshBuffer(
glh.RenderBuffered,
// Indices.
glh.NewIndexAttr(1, gl.UNSIGNED_BYTE, gl.STATIC_DRAW),
// Vertex positions have 3 components (x, y, z).
glh.NewPositionAttr(3, gl.FLOAT, gl.STATIC_DRAW),
// Colors have 4 components (r, g, b, a).
glh.NewColorAttr(4, gl.FLOAT, gl.STATIC_DRAW),
)
// Add the mesh to the buffer.
mb.Add(idx, pos, clr)
return mb
}
