Here's what I see as the method for getting 3D objects perspective-transformed to screen:
(pseudocode)
On update:
Create the camera matrix: c = camRotation * camTranslation
Create the view matrix by inverting the camera matrix: v = c^-1
Create the projection matrix using the standard perspective projection matrix terms
Create view-projection matrix: vp = p * v
For each entity
Create a model matrix using entity world position, rotation, and scale values
Multiply this specific entity's world transform matrix (the model matrix): mvp = vp * m
Set mvp as a uniform for vertex shader
glDrawElements(...);
Queries:
- Please offer your advice on whether or not the above structure is sensible.
- What options do I have to reduce the number of draw calls? Merging static geometry into a single vertex list using a common texture atlas seems to be the only option?
- Re the MVP matrix above, why do some sources present the final matrix value as -1, and others as 1? What should I use?
Any other tips, suggestions on this structure welcome.
Primary references:
OpenGL wiki page on viewing and transformations
Joe Groff's tutorial on transformation and projection
