// 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)
}
}
}
// drawScene renders the 3D models consisting of one VAO
func (tag *trtag) drawScene() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
tag.checkError("gl.Clear")
gl.UseProgram(tag.shaders)
tag.checkError("gl.UseProgram")
gl.BindVertexArray(tag.vao)
tag.checkError("gl.BindVertexArray")
// Use a modelview matrix and quaternion to rotate the 3D object.
tag.mvp64.SetQ(lin.NewQ().SetAa(0, 1, 0, lin.Rad(-tag.rotateAngle)))
tag.mvp64.TranslateMT(0, 0, -4)
tag.mvp.Set(tag.mvp64.Mult(tag.mvp64, tag.persp))
gl.UniformMatrix4fv(tag.mvpRef, 1, false, tag.mvp.Pointer())
if err := gl.GetError(); err != 0 {
fmt.Printf("gl.UniformMatrix error %d\n", err)
}
gl.DrawElements(gl.TRIANGLES, int32(len(tag.faces)), gl.UNSIGNED_BYTE, 0)
if err := gl.GetError(); err != 0 {
fmt.Printf("gl.DrawElements error %d\n", err)
}
// cleanup
gl.UseProgram(0)
tag.checkError("gl.UseProgram-0")
gl.BindVertexArray(0)
tag.checkError("gl.BindVertexArray-0")
// rotate based on time... not on how fast the computer runs.
if time.Now().Sub(tag.lastTime).Seconds() > 0.01 {
tag.rotateAngle += 1
tag.lastTime = time.Now()
}
}
// drawScene renders the shader-only scene.
func (sf *sftag) drawScene() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.UseProgram(sf.shaders)
gl.BindVertexArray(sf.vao)
timeSinceStart := time.Since(sf.sTime).Seconds()
gl.Uniform1f(sf.gTime, float32(timeSinceStart))
gl.Uniform2f(sf.sizes, 500, 500)
gl.UniformMatrix4fv(sf.mvpref, 1, false, sf.mvp.Pointer())
gl.DrawElements(gl.TRIANGLES, int32(len(sf.faces)), gl.UNSIGNED_BYTE, 0)
// cleanup
gl.UseProgram(0)
gl.BindVertexArray(0)
}
// drawScene renders the single texture on the quad.
func (rt *rtrace) drawScene() {
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.UseProgram(rt.shaders)
gl.Uniform1i(rt.tex2D, 0)
gl.ActiveTexture(gl.TEXTURE0 + 0)
gl.BindVertexArray(rt.vao)
gl.UniformMatrix4fv(rt.mvpId, 1, false, rt.mvp.Pointer())
gl.DrawElements(gl.TRIANGLES, int32(len(rt.faces)), gl.UNSIGNED_BYTE, 0)
// cleanup
gl.ActiveTexture(0)
gl.UseProgram(0)
gl.BindVertexArray(0)
}
// 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.mvp.Set(ld.mvp64.Mult(ld.mvp64, ld.persp))
gl.UniformMatrix4fv(ld.mvpref, 1, false, ld.mvp.Pointer())
gl.DrawElements(gl.TRIANGLES, ld.faceCount, gl.UNSIGNED_SHORT, 0)
// cleanup
gl.UseProgram(0)
gl.BindVertexArray(0)
}