# Any way to draw spaceship on top of terrain?

The screenshot above comes from the code below.

It’s a hodgepodge I made out of some code from @dave1707 and some code from @tnlogy.

Dave’s code is the spaceship and tnlogy’s code is the terrain.

It’s kind of complicated but all that really matters is this:

``````
function draw()
update(DeltaTime)
scene:draw()
updateCameraPos()
drawTerrain()
end

``````

Since 2D drawing has to happen after Craft drawing, I have to call `drawTerrain()` last, and I can’t figure out any way to get the spaceship to then draw in front of the terrain. Is there a way?

Full code:

``````
viewer.mode = OVERLAY

function setup()
assert(craft, "Please include Craft as a dependency")
createStartConditions()
createScene()
createShip()
createTerrain()
end

function draw()
update(DeltaTime)
scene:draw()
updateCameraPos()
drawTerrain()
end

function createStartConditions()
maxSpeed = 0.5
speed, ex, ey, ang = 0, 0, 45, 0
cameraX, cameraZ = -205, -205
hgx = Gravity.x
hgy = Gravity.y
end

function createScene()
scene = craft.scene()
scene.camera.position = vec3(cameraX, 0, cameraZ)
-- Adjust camera's initial rotation if needed
scene.camera.eulerAngles = vec3(0, ey, 0)
end

function createShip()
ship = scene:entity()
ship.model = craft.model(asset.builtin.SpaceKit.spaceCraft6_obj)
ship.scale = vec3(1, 1, 1) * 0.018
ship.parent = scene.camera
-- Adjust ship's position if needed
ship.position = ship.position + vec3(0, -HEIGHT * 0.0003, HEIGHT * 0.0015)
-- Correct the ship's rotation to face away from the camera initially
ship.eulerAngles = vec3(0, 180, 0) -- This line makes the ship face away
end

--createTerrain() and mult(m, v) are from tnology Terrain
function createTerrain()
forward, right, up = vec3(0, 0, 1), vec3(-1, 0, 0), vec3(0, 1, 0)
pos = vec3(0, 100, 0)
t = Terrain()
end

function update(dt)
scene:update(dt)
scene.camera.position = vec3(cameraX, 1, cameraZ)
scene.camera.eulerAngles = vec3(0, ey, 0)
checkTilt()
end

function drawTerrain()
-- tnology Terrain:
pushMatrix()
perspective(45, WIDTH / HEIGHT, 0.1, 500000)
local m = matrix()
forward, right, up = mult(m, forward), mult(m, right), mult(m, up)
local f = pos + forward
camera(pos.x, pos.y, pos.z, f.x, f.y, f.z, up.x, up.y, up.z)
translate(0, -30000, 0)
rotate(-92, 1, 0, 0)
t:draw(pos)
local v = 30000 * DeltaTime
pos.x, pos.z = pos.x + forward.x * v, pos.z + forward.z * v
popMatrix()
end

function updateCameraPos()
ey = ey - ang
cameraX = cameraX + x
cameraZ = cameraZ + z
end

function checkTilt()
local tiltX = Gravity.x
local tiltY = Gravity.y

-- Adjust ship's tilt based on x-axis tilt
ship.eulerAngles = vec3(0, 180, -tiltX * 50) -- Adjust multiplier for sensitivity

-- Rotate terrain by modifying the camera's angle based on the tilt
-- This simulates the terrain rotation underneath the ship
local terrainTiltFactor = 30 -- Adjust for sensitivity
ey = ey + (tiltX - hgx) * terrainTiltFactor
ex = ex + (tiltY - hgy) * terrainTiltFactor

-- Update previous tilt values for next calculation
hgx = tiltX
hgy = tiltY
end

--from tnology Terrain:

Terrain = class()

function Terrain:init(x)
local d,s = 2000,20
self.d, self.s = d,s
self.m = mesh()
for y=-s,s do
for x=-s,s do
end
end
self.m.texture = readImage("Cargo Bot:Crate Yellow 1")
self.m:setColors(
color(119, 60, 49, 61))
end

function Terrain:draw(pos)
math.sin(ElapsedTime),1):normalize()
pos =vec2(pos.x, pos.z)
local step = self.d*(self.s+.5)*2
local o = vec2(math.floor(pos.x/step+.5),
-math.floor(pos.y/step+.5))

-- drawing a 3x3 grid centered at camera position
-- for y=-1,1 do --tnology's original values
--  for x=-1,1 do
for y=-5, 5 do --boosting these to 5 makes it go much farther in the distance
for x=-5, 5 do
pushMatrix()
local u,v = (o.x+x)*step,(o.y+y)*step
translate(u,v,0)
self.m:draw()
popMatrix()
end
end
end

Perlin = [[
//
// Description : Array and textureless GLSL 2D simplex noise function.
//      Author : Ian McEwan, Ashima Arts.
//  Maintainer : ijm
//     Lastmod : 20110822 (ijm)
//               https://github.com/ashima/webgl-noise
//
vec3 mod289(vec3 x) {
return x - floor(x * (1.0 / 289.0)) * 289.0;
}
vec2 mod289(vec2 x) {
return x - floor(x * (1.0 / 289.0)) * 289.0;
}
vec3 permute(vec3 x) {
return mod289(((x*34.0)+1.0)*x);
}
float snoise(vec2 v)
{
const vec4 C = vec4(0.211324865405187,  // (3.0-sqrt(3.0))/6.0
0.366025403784439,  // 0.5*(sqrt(3.0)-1.0)
-0.577350269189626,  // -1.0 + 2.0 * C.x
0.024390243902439); // 1.0 / 41.0
// First corner
vec2 i  = floor(v + dot(v, C.yy) );
vec2 x0 = v -   i + dot(i, C.xx);
// Other corners
vec2 i1;
//i1.x = step( x0.y, x0.x ); // x0.x > x0.y ? 1.0 : 0.0
//i1.y = 1.0 - i1.x;
i1 = (x0.x > x0.y) ? vec2(1.0, 0.0) : vec2(0.0, 1.0);
// x0 = x0 - 0.0 + 0.0 * C.xx ;
// x1 = x0 - i1 + 1.0 * C.xx ;
// x2 = x0 - 1.0 + 2.0 * C.xx ;
vec4 x12 = x0.xyxy + C.xxzz;
x12.xy -= i1;
// Permutations
i = mod289(i); // Avoid truncation effects in permutation
vec3 p = permute( permute( i.y + vec3(0.0, i1.y, 1.0 ))
+ i.x + vec3(0.0, i1.x, 1.0 ));
vec3 m = max(0.5 - vec3(dot(x0,x0), dot(x12.xy,x12.xy), dot(x12.zw,x12.zw)), 0.0);
m = m*m ;
m = m*m ;
// Gradients: 41 points uniformly over a line, mapped onto a diamond.
// The ring size 17*17 = 289 is close to a multiple of 41 (41*7 = 287)
vec3 x = 2.0 * fract(p * C.www) - 1.0;
vec3 h = abs(x) - 0.5;
vec3 ox = floor(x + 0.5);
vec3 a0 = x - ox;
// Normalise gradients implicitly by scaling m
// Approximation of: m *= inversesqrt( a0*a0 + h*h );
m *= 1.79284291400159 - 0.85373472095314 * ( a0*a0 + h*h );
// Compute final noise value at P
vec3 g;
g.x  = a0.x  * x0.x  + h.x  * x0.y;
g.yz = a0.yz * x12.xz + h.yz * x12.yw;
return 130.0 * dot(m, g);
}
]]

uniform mat4 modelViewProjection;
attribute vec4 position;
attribute vec4 color;
attribute vec2 texCoord;
uniform vec3 light;
uniform vec3 pos;
uniform vec2 offset;
varying lowp vec4 vColor;
varying highp vec2 vTexCoord;

float h(vec2 p) {
p = p + offset;
return snoise(p*.001)*20. +
snoise((p-vec2(1.,1.))*.0001)*1000. +
snoise((p-vec2(1.,1.))*.00002)*5000.;
}

vec3 cnormal(vec2 p) {
float d = .01;
float h1 = h(p-vec2(d,0.)) - h(p+vec2(d,0.));
float h2 = h(p-vec2(0.,d)) - h(p+vec2(0.,d));
vec3 v = cross(vec3(d*2.,0.,h1),
vec3(0.,d*2.,h2));
return normalize(v);
}

void main() {
vColor = color;
vTexCoord = texCoord;
vec4 p = position;
p.z = p.z + h(p.xy);

if (light != vec3(0.,0.,0.)) {
lowp vec4 nor = vec4(cnormal(p.xy),0);
} else {
}
gl_Position = modelViewProjection * p;
}
]], [[
uniform lowp sampler2D texture;
varying lowp vec4 vColor;
varying highp vec2 vTexCoord;

void main() {
lowp vec4 res = texture2D(texture, vTexCoord);
lowp vec4 c = vColor;
gl_FragColor = c;
}
]])``````

You should be able to do something like this:

But there seems to be something buggy with setContext in Codea, so it’s not possible. It works if I only draw the sprites every 2th frame and the actual context every 2th frame. Maybe the depth buffer get trashed when drawing in the setContext, I don’t know.

@tnology - loaded your code up which uses the shader but won’t run fires up an error to mult() several times. I have set the camera dependencies on but no other. Any ideas why ?

It seems like @UberGoober forgot to include it in the pasted code. Add this:

``````
function mult(m, v) -- matrix multiplication
return vec3(
m[1]*v.x+m[2]*v.y+m[3]*v.z,
m[5]*v.x+m[6]*v.y+m[7]*v.z,
m[9]*v.x+m[10]*v.y+m[11]*v.z
)
end

``````
1 Like

@tnology - thanks for finding and posting the lost function. Pasted in and all seems to be functioning well now. It’s a great demo but pre many iOS updates which result in complications when trying to access the command buttons on the screen limits.

I’ll have a play with this to see if I can modify the control systems but don’t hold your breath, there’s a lot of code to digest.