// Renderer implementation.
// BindTexture makes the texture available on the GPU.
func (gc *opengl) BindTexture(tid *uint32, img image.Image, repeat bool) (err error) {
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
log.Printf("opengl:bindTexture need to find and fix prior error %X", glerr)
}
if *tid == 0 {
gl.GenTextures(1, tid)
}
gl.BindTexture(gl.TEXTURE_2D, *tid)
// FUTURE: check if RGBA, or NRGBA are alpha pre-multiplied. The docs say yes
// for RGBA but the data is from PNG files which are not pre-multiplied
// and the go png Decode looks like its reading values directly.
var ptr gl.Pointer
bounds := img.Bounds()
width, height := int32(bounds.Dx()), int32(bounds.Dy())
switch imgType := img.(type) {
case *image.RGBA:
i := img.(*image.RGBA)
ptr = gl.Pointer(&(i.Pix[0]))
case *image.NRGBA:
i := img.(*image.NRGBA)
ptr = gl.Pointer(&(i.Pix[0]))
default:
return fmt.Errorf("Unsupported image format %T", imgType)
}
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, ptr)
gl.GenerateMipmap(gl.TEXTURE_2D)
gc.setTextureMode(*tid, repeat)
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
err = fmt.Errorf("Failed binding texture %d\n", glerr)
}
return err
}
// Render implementation.
// FUTURE: all kinds of possible optimizations that would need to be
// profiled before implementing.
// • group by vao to avoid switching vao's.
// • group by texture to avoid switching textures.
// • use interleaved vertex data.
// • uniform buffers http://www.opengl.org/wiki/Uniform_Buffer_Object.
// • ... lots more possiblities... leave your fav here.
func (gc *opengl) Render(dr Draw) {
d, ok := dr.(*draw)
if !ok || d == nil {
return
}
// switch state only if necessary.
if gc.depthTest != d.depth {
if d.depth {
gl.Enable(gl.DEPTH_TEST)
} else {
gl.Disable(gl.DEPTH_TEST)
}
gc.depthTest = d.depth
}
// switch shaders only if necessary.
if gc.shader != d.shader {
gl.UseProgram(d.shader)
gc.shader = d.shader
}
// Ask the model to bind its provisioned uniforms.
// FUTURE: only need to bind uniforms that have changed.
gc.bindUniforms(d)
// bind the data buffers and render.
gl.BindVertexArray(d.vao)
switch d.mode {
case LINES:
gl.PolygonMode(gl.FRONT_AND_BACK, gl.LINE)
gl.DrawElements(gl.LINES, d.numFaces, gl.UNSIGNED_SHORT, 0)
gl.PolygonMode(gl.FRONT_AND_BACK, gl.FILL)
case POINTS:
gl.Enable(gl.PROGRAM_POINT_SIZE)
gl.DrawArrays(gl.POINTS, 0, d.numVerts)
gl.Disable(gl.PROGRAM_POINT_SIZE)
case TRIANGLES:
if len(d.texs) > 1 && d.texs[0].fn > 0 {
// Multiple textures on one model specify which verticies they apply to.
for _, tex := range d.texs {
// Use the same texture unit and sampler. Just update which
// image is being sampled.
gl.BindTexture(gl.TEXTURE_2D, tex.tid)
// fn is the number of triangles, 3 indicies per triangle.
// f0 is the offset in triangles where each triangle has 3 indicies
// of 2 bytes (uShort) each.
gl.DrawElements(gl.TRIANGLES, tex.fn*3, gl.UNSIGNED_SHORT, int64(3*2*tex.f0))
}
} else {
// Single textures are handled with a standard bindUniforms
gl.DrawElements(gl.TRIANGLES, d.numFaces, gl.UNSIGNED_SHORT, 0)
}
}
}
// BindFrame creates a framebuffer object with an associated texture.
// http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-14-render-to-texture/
// http://www.opengl-tutorial.org/intermediate-tutorials/tutorial-16-shadow-mapping/
func (gc *opengl) BindFrame(buf int, fbo, tid, db *uint32) (err error) {
size := int32(1024)
gl.GenFramebuffers(1, fbo)
gl.BindFramebuffer(gl.FRAMEBUFFER, *fbo)
// Create a texture specifically for the framebuffer.
gl.GenTextures(1, tid)
gl.BindTexture(gl.TEXTURE_2D, *tid)
switch buf {
case IMAGE_BUFF:
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, size, size,
0, gl.RGBA, gl.UNSIGNED_BYTE, gl.Pointer(nil))
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
// Add a depth buffer to mimic the normal framebuffer behaviour for 3D objects.
gl.GenRenderbuffers(1, db)
gl.BindRenderbuffer(gl.RENDERBUFFER, *db)
gl.RenderbufferStorage(gl.RENDERBUFFER, gl.DEPTH_COMPONENT, size, size)
gl.FramebufferRenderbuffer(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, gl.RENDERBUFFER, *db)
// Associate the texture with the framebuffer.
gl.FramebufferTexture(gl.FRAMEBUFFER, gl.COLOR_ATTACHMENT0, *tid, 0)
buffType := uint32(gl.COLOR_ATTACHMENT0)
gl.DrawBuffers(1, &buffType)
case DEPTH_BUFF:
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.DEPTH_COMPONENT16, size, size,
0, gl.DEPTH_COMPONENT, gl.FLOAT, gl.Pointer(nil))
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_FUNC, gl.LEQUAL)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_COMPARE_MODE, gl.COMPARE_REF_TO_TEXTURE)
// Associate the texture with the framebuffer.
gl.FramebufferTexture(gl.FRAMEBUFFER, gl.DEPTH_ATTACHMENT, *tid, 0)
gl.DrawBuffer(gl.NONE)
default:
return fmt.Errorf("BindFrame unrecognized buffer type.")
}
// Report any problems.
glerr := gl.CheckFramebufferStatus(gl.FRAMEBUFFER)
if glerr != gl.FRAMEBUFFER_COMPLETE {
return fmt.Errorf("BindFrame error %X", glerr)
}
if glerr := gl.GetError(); glerr != gl.NO_ERROR {
err = fmt.Errorf("Failed binding framebuffer %X", glerr)
}
gl.BindFramebuffer(gl.FRAMEBUFFER, 0) // clean up by resetting to default framebuffer.
return err
}
// setTextureMode is used to switch to a repeating
// texture instead of a 1:1 texture mapping.
func (gc *opengl) setTextureMode(tid uint32, repeat bool) {
gl.BindTexture(gl.TEXTURE_2D, tid)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAX_LEVEL, 7)
if repeat {
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.REPEAT)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.REPEAT)
} else {
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_S, gl.CLAMP_TO_EDGE)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_WRAP_T, gl.CLAMP_TO_EDGE)
}
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.LINEAR)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST_MIPMAP_LINEAR)
}
// useTexture makes the given texture the active texture.
func (gc *opengl) useTexture(sampler, texUnit int32, tid uint32) {
gc.bindUniform(sampler, i1, 1, texUnit)
gl.ActiveTexture(gl.TEXTURE0 + uint32(texUnit))
gl.BindTexture(gl.TEXTURE_2D, tid)
}
// initRender is one time initialization that creates a single VAO
// to display a single ray trace generated texture.
func (rt *rtrace) initRender() {
rt.verts = []float32{ // four verticies for a quad.
0, 0, 0,
4, 0, 0,
0, 4, 0,
4, 4, 0,
}
rt.faces = []uint8{ // create quad from 2 triangles.
0, 2, 1,
1, 2, 3,
}
rt.uvs = []float32{ // texture coordinates to sample the image.
0, 0,
1, 0,
0, 1,
1, 1,
}
// Start up OpenGL and create a single vertex array object.
gl.Init()
gl.GenVertexArrays(1, &rt.vao)
gl.BindVertexArray(rt.vao)
// vertex data.
var vbuff uint32
gl.GenBuffers(1, &vbuff)
gl.BindBuffer(gl.ARRAY_BUFFER, vbuff)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(rt.verts)*4), gl.Pointer(&(rt.verts[0])), gl.STATIC_DRAW)
gl.VertexAttribPointer(0, 3, gl.FLOAT, false, 0, 0)
gl.EnableVertexAttribArray(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(rt.faces)), gl.Pointer(&(rt.faces[0])), gl.STATIC_DRAW)
// texture coordatinates
var tbuff uint32
gl.GenBuffers(1, &tbuff)
gl.BindBuffer(gl.ARRAY_BUFFER, tbuff)
gl.BufferData(gl.ARRAY_BUFFER, int64(len(rt.uvs)*4), gl.Pointer(&(rt.uvs[0])), gl.STATIC_DRAW)
var tattr uint32 = 2
gl.VertexAttribPointer(tattr, 2, gl.FLOAT, false, 0, 0)
gl.EnableVertexAttribArray(tattr)
// use ray trace generated texture image.
bounds := rt.img.Bounds()
width, height := int32(bounds.Dx()), int32(bounds.Dy())
ptr := gl.Pointer(&(rt.img.Pix[0]))
gl.GenTextures(1, &rt.texId)
gl.BindTexture(gl.TEXTURE_2D, rt.texId)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MAG_FILTER, gl.NEAREST)
gl.TexParameteri(gl.TEXTURE_2D, gl.TEXTURE_MIN_FILTER, gl.NEAREST)
gl.TexImage2D(gl.TEXTURE_2D, 0, gl.RGBA, width, height, 0, gl.RGBA, gl.UNSIGNED_BYTE, ptr)
// texture sampling shader.
loader := load.NewLoader()
shader := "tuv"
vsrc, verr := loader.Vsh(shader)
fsrc, ferr := loader.Fsh(shader)
if verr != nil || ferr != nil {
log.Fatalf("Failed to load shaders %s %s\n", verr, ferr)
}
rt.shaders = gl.CreateProgram()
if err := gl.BindProgram(rt.shaders, vsrc, fsrc); err != nil {
log.Fatalf("Failed to create program: %s\n", err)
}
rt.mvpId = gl.GetUniformLocation(rt.shaders, "mvpm")
rt.tex2D = gl.GetUniformLocation(rt.shaders, "sampler2D")
rt.mvp = render.NewMvp().Set(lin.NewM4().Ortho(0, 4, 0, 4, 0, 10))
// set some state that doesn't need to change during drawing.
gl.ClearColor(0.0, 0.0, 0.0, 1.0)
}