Animations

OpenGL OpenGL: Basic Coding
1

I’m having problems with implementing animations that are controlled by equations.

Im currently doing simple rotations. When rotating in x it seems to work fine but when rotating in y or z it turns a but and then just stops. Ive checked the values being returned from my maths and they all increase as they should, so i cant figure out why its doing this.

Can anyone help??

2

can you display some code? it would help a lot.

:regards:

3

well this is the code i use to work out the rotations for the x y z angles

if(animTime>=0){ 
		object.animRotate.x=object.rotation.x+(animations.axis.x*(animTime*animations.speed));
		object.animRotate.y=object.rotation.y+(animations.axis.y*(animTime*animations.speed));
		object.animRotate.z=object.rotation.z+(animations.axis.z*(animTime*animations.speed));
		}

its pretty much initial rotation +speedtime. The mutltiplication before speedtime is the axis that the rotation is being performed on.

4

Put glPushMatrix() - glPopMatrix() around your glRotate() maybe ?

5

yeah i have glpush and glpop. heres my drawing code:

void Recursive_Draw(TreeStorageNode object)
{
	int i;
	TreeStorageNode animatedObject;

	glPushMatrix();

	

	for(i=0; i<animationData->controllerCount;i++){
		if(strcmp(animationData->controllers[i].controlledObject, object.objectName)==0){
			animatedObject=Update_Animation(object, animationData->controllers[i], newSimTime);
			i=animationData->controllerCount;
		

			printf("ROTX %.2f ROTY %.2f ROTZ %.2f

", animatedObject.animRotate.x, animatedObject.animRotate.y, animatedObject.animRotate.z); 
			glRotatef(animatedObject.animRotate.x, animatedObject.animRotate.y, animatedObject.animRotate.z, object.rotation.w);
		}
	}

	printf("EXIT

");

	
	glTranslatef(animPosition.x, animPosition.y, animPosition.z);
	
	glVertexPointer(3, GL_FLOAT, sizeof(VectorStorage), &object.mesh[0].pos);
	glNormalPointer(GL_FLOAT, sizeof(VectorStorage), &object.mesh[0].normal);
	glTexCoordPointer(2, GL_FLOAT, sizeof(VectorStorage), &object.mesh[0].texCoord);
	glDrawElements(GL_TRIANGLES, 3*object.mesh->triangleCount, GL_UNSIGNED_INT, object.mesh->indices);

	

	if(object.childCount!=0){
		for(i=0; i<object.childCount; i++)
			Recursive_Draw(object.childrenPointers[i]);
	}

	glPopMatrix();
}

its not great but it reflects my rather rubbish programming techniques

6

>> glRotatef(animatedObject.animRotate.x, animatedObject.animRotate.y, animatedObject.animRotate.z, object.rotation.w);

Hehe, :stuck_out_tongue: don’t forget to read the docs :wink:
glRotate is defined as :
glRotatef (GLfloat angle, GLfloat x, GLfloat y, GLfloat z);

So you need to use :

glRotatef( rotate.z , 0,0,1);
glRotatef( rotate.x , 1,0,0);
glRotatef( rotate.y , 0,1,0);

The correct order will depend of your case.

7

ohh im so dumb. thanks very much, most problems i come across are ones like these it gets a bit tiresome hehehe.

ps it works like a dream

8

ok so i have the animations working just perfectly but now things are rotating around the axis of other objects axis. I was thinking it was my pop push matrices being in the wrong place but ive looked over it and i cant see that its wrong.

can someone with a fresh pair of eyes see if this is the problem. the code from above hasnt changed much from what i currently have. so if there is a problem it will be in there.

cheers for any help