Animation in Minecraft Movement within Movement Copyright © 2015 – Curt Hill

Introduction If we created an entity that was a derivation of EntityCreature it will move –This is part of its inherited behavior –It will move in a semi-random fashion If it is modeled with multiple boxes it will move in an unrealistic fashion –It will look like the figure is frozen in a block of ice and the block is drug around Now we set out to fix this

The Modeler The derivation of ModelBase contains a render method In the example this class is CurtModelEmu All the animation work is done in this method or the methods it calls The movements we apply here are strictly ornamental –They just make things more realistic Copyright © 2015 – Curt Hill

The render method This is called multiple times a second The parent piece is moved by Minecraft We use this method to move appendages Not so much move as rotate them on the body or to whatever they are attached Copyright © 2015 – Curt Hill

Angles There are three angle properties in ModelRenderer –Recall that each box is an object of this type rotateAngleX, rotateAngleY and rotateAngleZ These determine the angles of the box –For the parent this is relative to the coordinate system –For children this is relative to the parent and attachment point Copyright © 2015 – Curt Hill

Interlude on Angles Most of us are used to measuring angles in degrees Java only believes in radians for measuring angles –Java follows mathematics and science in this belief There are 2π radians in 360° A good article as to why radians are superior is: Copyright © 2015 – Curt Hill

Table Copyright © 2015 – Curt Hill DegreesRadians

Angles Again Like a good mathematician I will only use radians in code and examples If you are stuck in bad practice use this conversion function: float degToRad(float deg){ return deg*(float)Math.PI/180; } Copyright © 2015 – Curt Hill

The rotates Each of the rotateAngle variables take radians They set the box to that angle immediately Typically you wish to avoid large angular changes Moreover, you also need to be sensitive to motion of the entity Copyright © 2015 – Curt Hill

Disjointed Action An appendage rotating has to occur over a time period Thus each call to render moves it some distance but not usually the total distance We also need to keep track of progress There are several practical techniques that we can use Copyright © 2015 – Curt Hill

A Counter We need a counter that tells which visit to render we are currently in This is usually an instance variable of the class –May also be a static local variable of render Each call to render we increment it We want this value to be in some range which is usually less than 50 –We either divide and keep remainder or zero it periodically Copyright © 2015 – Curt Hill

Selective Actions Once the counter is set and in the right range, how do we use it? Two good ways: –Use as an index in a constant array to store the values –Use as the selector in a switch case Lets turn the emu’s head in both ways Copyright © 2015 – Curt Hill

The Counter in Modeler Copyright © 2015 – Curt public class CurtModelEmu extends ModelBase{ public ModelRenderer body; public ModelRenderer leg1; public ModelRenderer leg2; public ModelRenderer neck; public ModelRenderer head; protected int headCycle=0;

The renderEmu Copyright © 2015 – Curt Hill public void renderEmu( CurtEmu ent, float time, float swingSuppress, float par4, float headAngleY, float headAngleX, float par7) { setRotationAngles(time, swingSuppress, par4, headAngleY, headAngleX, par7, ent); body.render(par7); }

Comments The above two methods will be the same for both approaches Notice that we set the angles Then we render the body Since the body is the parent, all the children will also be rendered The renderEmu routine gets all the parameters, but I will not use any of them, nor show them here Next two versions of renderEmu Copyright © 2015 – Curt Hill

Using a Switch Copyright © 2015 – Curt public void setRotationAngles(…){ switch (headCycle++%20) case 3: head.rotateAngleY =.2F; break; case 4: head.rotateAngleY =.4F; break; case 5: head.rotateAngleY =.5f; break; …

Array Copyright © 2015 – Curt Hill float turns[] = new float[]{0f, 0f, 0f,.2f,.4f,.5f,.5f,.4f,.2f, 0f,0f,-.2f,-.4f,-.5f,-.5f, -.4f, -.2f, 0f,0f, 0f,0f,0f}; public void setRotationAngles(…){ head.rotateAngleY = turns[headCycle++%20]; }

Comparison The switch is much more code In the array fill in gaps that the switch does not Also beware of subscripting errors Once the basic approach is set, it is easy to make it faster or slower or make the rotation greater or lesser Copyright © 2015 – Curt Hill

Motion The emu moves its head all the time However, you do not want the legs to walk when the emu is standing still How do we detect motion? Copyright © 2015 – Curt Hill

Entities Again Entities have several properties of value here posX, prevPosX and the corresponding Y and Z items Comparing current and previous for X and Z will tell if this item is moving in the plane or not –Changing Y would be a jump We can then test the current and previous and only animate if there is motion Copyright © 2015 – Curt Hill

Head wagging All the suggestions so far given are synchronous All the emus will wag their heads at the same time –Looks unnatural –Not really a problem with walking We can vary this by introducing some randomness Insert a random object and cancel occasional ticks before the wag Copyright © 2015 – Curt Hill

The Final Routines In the following screens are the final animations produced in this presentation Copyright © 2015 – Curt Hill

setRotationAngles Copyright © 2015 – Curt public void setRotationAngles(…){ setHeadAngle(); setLegAngles(ent); }

setHeadAngle Copyright © 2015 – Curt Hill protected void setHeadAngle(){ if(headCycle%20 < 3){ int r = rand.nextInt(10); if(r<6){ headCycle = 0; return; } head.rotateAngleY = turns[headCycle++%20]; }

setLegAngles Copyright © 2015 – Curt Hill protected void setLegAngles (Entity ent){ if(ent.prevPosX==ent.posX && ent.prevPosZ==ent.posZ){ // no motion leg1.rotateAngleX = 0f; leg2.rotateAngleX = 0f; legCycle = 0; } else { leg1.rotateAngleX = walks[legCycle++%11]; leg2.rotateAngleX = -leg1.rotateAngleX; }

Concussion Now we are ready to create harmless entities Helping non-harmless entities to attack or flee must await the next presentation Copyright © 2015 – Curt Hill