3d object coloring only one face.

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Ones and Zeros

17

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Joined: 7th Jun 2007

Location: Western NY

Posted: 9th Feb 2013 02:40 Edited at: 9th Feb 2013 17:02

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Playing around with some 3d objects and flying a camera around. I made 2 cubes so far and colored them different colors. When I move the camera past cube 1 colored red and then turn the camera the other five sides of the cube are just gray. Same thing happens to cube 2. Only the sides facing the camera at start up get colored. Is this normal or do I need to do more to color all sides. Also I was thinking of using CSG to hollow out a bigger cube with a smaller cube to make the inside of the cube my game area borders (visually) (Shoot the flying bouncing off wall spheres type thing)and hidden boxes for collision. Would the color goto the inside of the hollowed out cube too? I figured this would be a good way try and focus my learning direction. Come up with an idea and try to make it work.

I made a light and updated its position to the camera position and this seemed to work. Is this the best way? What are other options?

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29 games

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Joined: 23rd Nov 2005

Location: not entirely sure

Posted: 10th Feb 2013 22:32 Edited at: 10th Feb 2013 22:33

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This is normal. It's to do with the way the default lighting works. There are some commands that are used to alter how light works on an object.

SET OBJECT DIFFUSE
SET OBJECT AMBIENCE
SET OBJECT SPECULAR
SET OBJECT EMISSIVE

I think there are some others, best have a look at the BASIC3D COMMANDS -> APPEARANCE COMMANDS in the help files.

This demo use the SET OBJECT EMISSIVE command.

+ Code Snippet

sync on
sync rate 60
autocam off
hide mouse

make matrix 1, 100,100,10,10

make object cube 1, 10
color object 1, rgb(255,0,0)
set object emissive 1, rgb(100,0,0)
position object 1, 50,5,50

position camera 50,5,0

do

	move camera (upkey()-downkey())
	turn camera right (rightkey()-leftkey())

	text 0,0, "Use arrow keys to move"
	
	sync

loop

If you remark out the line "set object emissive 1, rgb(100,0,0)" then some of the faces will turn grey again.

I've not really used the DIFFUSE, AMBIENCE or SPECULAR but you might help you. As you've already mentioned, you could use lights (which are quite slow so you might not want to use them for larger projects) or you could use a texture to give your objects colour. I think you can also set the diffuse, specular and emissive qualities of the object using textures but I might be wrong. Then there are shaders but that's a whole other issue and is something that you might not want to get into straight away.

one of these days I'll come up with a better signature

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zeroSlave

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Joined: 13th Jun 2009

Location: Springfield

Posted: 10th Feb 2013 22:49 Edited at: 10th Feb 2013 23:21

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Instead of hollowing out a cube to get a playing level, just turn it inside out! SCALE OBJECT yourWorld -100, -100, -100.

As 29 games said, It's a normal behavior. When I'm messing about with colors on objects and such, I typically set up the lighting as follows:

`Set up our screen
sync on
sync rate 60
color backdrop rgb(0,0,0)
autocam off

`Set up lights
hide light 0                    `Light 0 is on by default And I typically hide it.
set ambient light 0             `This sets how much 'ambient' light there is in the world. I set it to 0.
make light 1                    `Make a light you can control
position light 1, 0, 30, 0     `Position the light

`Make an object to represent where the light is:
make object sphere 100, 10      `Make a sphere
set object light 100, 0         `Turn the light off for this object.
position object 100, 0, 30, 0  `Position it where the light is

`Make some cubes, position them and color them randomly
for i = 1 to 10
    make object cube i, 10
    color object i, rgb(rnd(255), rnd(255), rnd(255))
    position object i, rnd(100) - 50, 0, rnd(100) - 50
next i

`Main loop!
do
    `update camera
    CamAngle = wrapValue(CamAngle + 1)
    position camera sin(CamAngle) * 100, 50, cos(CamAngle) * 100
    point camera 0,0,0
    
    sync
loop
end

+ Code Snippet

`Set up our screen
sync on
sync rate 60
color backdrop rgb(0,0,0)
autocam off

`Set up lights
hide light 0                    `Light 0 is on by default And I typically hide it.
set ambient light 0             `This sets how much 'ambient' light there is in the world. I set it to 0.
make light 1                    `Make a light you can control
position light 1, 0, 30, 0     `Position the light

`Make an object to represent where the light is:
make object sphere 100, 10      `Make a sphere
set object light 100, 0         `Turn the light off for this object.
position object 100, 0, 30, 0  `Position it where the light is

`Make some cubes, position them and color them randomly
for i = 1 to 10
    make object cube i, 10
    color object i, rgb(rnd(255), rnd(255), rnd(255))
    position object i, rnd(100) - 50, 0, rnd(100) - 50
next i

`Main loop!
do
    `update camera
    CamAngle = wrapValue(CamAngle + 1)
    position camera sin(CamAngle) * 100, 50, cos(CamAngle) * 100
    point camera 0,0,0
    
    sync
loop
end

Then test from there!

The reason you are getting grey sides, is because they are 'in the dark'. SET AMBIENT LIGHT percent will set how strong the ambient light actually is. I'm not sure what the default value is (maybe between 30-40%. Not sure :\) I typically set this to 0 so that I can get 'cleaner' looking DBP lighting.

There is no light source hitting the surface, so the ambient lighting will be applied. (It's actually applied all the time and can cause object coloring to look washed out on objects in light.). The ambient color is set to a grey color by default. If you COLOR AMBIENT LIGHT RGB(r, g, b), objects 'in the dark' will be the color you specify. Objects in light will be as well. The RGB is added between the the objects color by lights, and the color and power of the ambient.

Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing that it is stupid.

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