// reset our viewport after a window resize
func resizeWindow(width, height int) {
// protect against a divide by zero
if height == 0 {
height = 1
}
// Setup our viewport
gl.Viewport(0, 0, int(width), int(height))
// change to the projection matrix and set our viewing volume.
gl.MatrixMode(gl.PROJECTION)
gl.LoadIdentity()
// aspect ratio
aspect := gl.GLdouble(gl.GLfloat(width) / gl.GLfloat(height))
// Set our perspective.
// This code is equivalent to using gluPerspective as in the original tutorial.
var fov, near, far gl.GLdouble
fov = 45.0
near = 0.1
far = 100.0
top := gl.GLdouble(math.Tan(float64(fov*math.Pi/360.0))) * near
bottom := -top
left := aspect * bottom
right := aspect * top
gl.Frustum(float64(left), float64(right), float64(bottom), float64(top), float64(near), float64(far))
// Make sure we're changing the model view and not the projection
gl.MatrixMode(gl.MODELVIEW)
// Reset the view
gl.LoadIdentity()
}
func initStars() {
// Create the first stars
for loop, _ := range stars {
stars[loop] = &Star{
angle: 0.0,
dist: (gl.GLfloat(loop) / gl.GLfloat(num)) * 5.0,
r: gl.GLubyte(rand.Float32() * 255),
g: gl.GLubyte(rand.Float32() * 255),
b: gl.GLubyte(rand.Float32() * 255),
}
}
}
func atof(s []byte) gl.GLfloat {
f, err := strconv.ParseFloat(string(s), 32)
if err != nil {
panic(err)
}
return gl.GLfloat(f)
}
// Here goes our drawing code
func drawGLScene(sector Sector) {
xtrans := gl.GLfloat(-xpos)
ztrans := gl.GLfloat(-zpos)
ytrans := gl.GLfloat(-walkbias - 0.25)
scenroty := gl.GLfloat(360.0 - yrot)
// Clear the screen and depth buffer
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
// reset the view
gl.LoadIdentity()
// Rotate up and down to look up and down
gl.Rotatef(float32(lookupdown), 1.0, 0.0, 0.0)
// Rotate depending on direction player is facing
gl.Rotatef(float32(scenroty), 0.0, 1.0, 0.0)
// translate the scene based on player position
gl.Translatef(float32(xtrans), float32(ytrans), float32(ztrans))
gl.BindTexture(gl.TEXTURE_2D, uint(textures[filter]))
for _, vertices := range sector {
gl.Begin(gl.TRIANGLES)
for _, triangle := range *vertices {
gl.Normal3f(0.0, 0.0, 1.0)
gl.TexCoord2f(float32(triangle.u), float32(triangle.v))
gl.Vertex3f(float32(triangle.x), float32(triangle.y), float32(triangle.z))
}
gl.End()
}
// Draw to the screen
sdl.GL_SwapBuffers()
// Gather our frames per second
frames++
t := sdl.GetTicks()
if t-t0 >= 5000 {
seconds := (t - t0) / 1000.0
fps := frames / seconds
fmt.Println(frames, "frames in", seconds, "seconds =", fps, "FPS")
t0 = t
frames = 0
}
}
// Here goes our drawing code
func drawGLScene() {
// Clear the screen and depth buffer
gl.Clear(gl.COLOR_BUFFER_BIT | gl.DEPTH_BUFFER_BIT)
gl.BindTexture(gl.TEXTURE_2D, uint(texture))
for loop, star := range stars {
gl.LoadIdentity()
gl.Translatef(0.0, 0.0, float32(zoom))
gl.Rotatef(float32(tilt), 1.0, 0.0, 0.0)
gl.Rotatef(float32(star.angle), 0.0, 1.0, 0.0)
gl.Translatef(float32(star.dist), 0.0, 0.0)
gl.Rotatef(float32(-star.angle), 0.0, 1.0, 0.0)
gl.Rotatef(float32(-tilt), 1.0, 0.0, 0.0)
if twinkle {
other := stars[(num-loop)-1]
gl.Color4ub(uint8(other.r), uint8(other.g), uint8(other.b), 255)
gl.Begin(gl.QUADS)
gl.TexCoord2f(0.0, 0.0)
gl.Vertex3f(-1.0, -1.0, 0.0)
gl.TexCoord2f(1.0, 0.0)
gl.Vertex3f(1.0, -1.0, 0.0)
gl.TexCoord2f(1.0, 1.0)
gl.Vertex3f(1.0, 1.0, 0.0)
gl.TexCoord2f(0.0, 1.0)
gl.Vertex3f(-1.0, 1.0, 0.0)
gl.End()
}
gl.Rotatef(float32(spin), 0.0, 0.0, 1.0)
gl.Color4ub(uint8(star.r), uint8(star.g), uint8(star.b), 255)
gl.Begin(gl.QUADS)
gl.TexCoord2f(0.0, 0.0)
gl.Vertex3f(-1.0, -1.0, 0.0)
gl.TexCoord2f(1.0, 0.0)
gl.Vertex3f(1.0, -1.0, 0.0)
gl.TexCoord2f(1.0, 1.0)
gl.Vertex3f(1.0, 1.0, 0.0)
gl.TexCoord2f(0.0, 1.0)
gl.Vertex3f(-1.0, 1.0, 0.0)
gl.End()
spin += 0.01
star.angle += gl.GLfloat(loop) / gl.GLfloat(num)
star.dist -= 0.01
if star.dist < 0.0 {
star.dist += 5.0
star.r = gl.GLubyte(rand.Float32() * 255)
star.g = gl.GLubyte(rand.Float32() * 255)
star.b = gl.GLubyte(rand.Float32() * 255)
}
}
// Draw to the screen
sdl.GL_SwapBuffers()
// Gather our frames per second
frames++
t := sdl.GetTicks()
if t-t0 >= 5000 {
seconds := (t - t0) / 1000.0
fps := frames / seconds
fmt.Println(frames, "frames in", seconds, "seconds =", fps, "FPS")
t0 = t
frames = 0
}
}