// initScene is one time initialization that creates a single VAO
func (tag *trtag) initScene() {
tag.mvp64 = lin.NewM4()
tag.mvp32 = &render.M4{}
tag.persp = lin.NewPersp(60, float64(600)/float64(600), 0.1, 50)
tag.initData()
// Bind the OpenGL calls and dump some version info.
gl.Init()
fmt.Printf("%s %s", gl.GetString(gl.RENDERER), gl.GetString(gl.VERSION))
fmt.Printf(" GLSL %s\n", gl.GetString(gl.SHADING_LANGUAGE_VERSION))
// Gather the one scene into this one vertex array object.
gl.GenVertexArrays(1, &tag.vao)
gl.BindVertexArray(tag.vao)
// create shaders
tag.initShader()
gl.UseProgram(tag.shaders)
// vertex data.
var vbuff uint32
gl.GenBuffers(1, &vbuff)
gl.BindBuffer(gl.ARRAY_BUFFER, vbuff)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(tag.points)*4), gl.Pointer(&(tag.points[0])), gl.STATIC_DRAW)
vattr := uint32(gl.GetAttribLocation(tag.shaders, "in_Position"))
gl.EnableVertexAttribArray(vattr)
gl.VertexAttribPointer(vattr, 4, gl.FLOAT, false, 0, 0)
// colour data.
var cbuff uint32
gl.GenBuffers(1, &cbuff)
gl.BindBuffer(gl.ARRAY_BUFFER, cbuff)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(tag.colour)*4), gl.Pointer(&(tag.colour[0])), gl.STATIC_DRAW)
cattr := uint32(gl.GetAttribLocation(tag.shaders, "in_Color"))
gl.EnableVertexAttribArray(cattr)
gl.VertexAttribPointer(cattr, 4, gl.FLOAT, false, 0, 0)
// faces data.
var ebuff uint32
gl.GenBuffers(1, &ebuff)
gl.BindBuffer(gl.ELEMENT_ARRAY_BUFFER, ebuff)
gl.BufferData(gl.ELEMENT_ARRAY_BUFFER, int64(len(tag.faces)), gl.Pointer(&(tag.faces[0])), gl.STATIC_DRAW)
// set some state that doesn't need to change during drawing.
gl.ClearColor(0.0, 0.0, 0.0, 1.0)
gl.Enable(gl.DEPTH_TEST)
gl.Enable(gl.CULL_FACE)
gl.CullFace(gl.BACK)
}
// render draws the scene consisting of one VAO
func (ld *ldtag) render() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.UseProgram(ld.shaders)
gl.BindVertexArray(ld.vao)
// use a model-view-projection matrix
ld.mvp64.Set(lin.M4I).ScaleSM(0.5, 0.5, 0.5).TranslateMT(0, 0, -2)
ld.mvp64.Mult(ld.mvp64, ld.persp)
v3 := renderMatrix(ld.mvp64, ld.mvp32)
gl.UniformMatrix4fv(ld.mvpref, 1, false, v3.Pointer())
gl.CullFace(gl.BACK)
gl.DrawElements(gl.TRIANGLES, ld.faceCount, gl.UNSIGNED_SHORT, gl.Pointer(nil))
// cleanup
gl.UseProgram(0)
gl.BindVertexArray(0)
}