OpenGL 3D Game Tutorial 8: Model, View & Projection Matrices
1,961LWJGL tutorial series on how to create a 3D Java game with OpenGL!
This week create a rotating 3D cube using model, view and projection matrices!
Full code download for this episode:
https://www.dropbox.com/sh/1glu6x4ajd6y4mw/AAB2jWQk3AuCnVQfORhmSPiXa?dl=0
Cube vertices: https://www.dropbox.com/s/xcq0xa3yqr4vmh8/cube%20vertices%20data.txt?dl=0
Projection Matrix Explained: http://www.songho.ca/opengl/gl_projectionmatrix.html
LWJGL Wiki:
http://wiki.lwjgl.org/wiki/Main_Page
Common Problems:
-Don't forget to multiply the transformation matrix with the vertex position in the vertex shader. This was shown at the end of the last tutorial.
-Calling the getAllUniformLocations() method: We did this in the last episode in the ShaderProgram class constructor, a lot of people leave this out accidentally.
- In the getAllUniformLocations() method make sure that you're setting the value of the "location_transformationMatrix" variable. Getting the location is not enough, you need to store it too!
-After adding the projection matrix your entity's z position needs to be more negative than -NEAR_PLANE, otherwise it will be outside the view of the "camera". Set your entity's z position to -1 like I did at 11:38 in the video.
-The order that you multiply the matrices together in the vertex shader matters! Matrices are not like normal numbers, and multiplying them together in a different order will give you a different result.
-The spelling of the uniform variable names: The names must be spelled EXACTLY the same in the StaticShader getAllUniformLocations() method as they are in the shader code.
-The projection matrix code: Double check the code for the projection matrix, I've had quite a few emails from people who have had errors, and it has ended up being a mistake in the createProjectionMatrix() method.
-When creating the transformation matrix make sure that you didn't copy and paste the 3 rotation lines and forget to change them for each axis. Make sure that it looks like this:
Matrix4f.rotate((float) Math.toRadians(rx), new Vector3f(1, 0, 0), matrix, matrix);
Matrix4f.rotate((float) Math.toRadians(ry), new Vector3f(0, 1, 0), matrix, matrix);
Matrix4f.rotate((float) Math.toRadians(rz), new Vector3f(0, 0, 1), matrix, matrix);
Check the vectors and the rx, ry, and rz!
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End of video music- Kai Engel, "Waking Stars":
http://freemusicarchive.org/music/Kai...
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