Rotation of my cube based on arcball quaternion rotation matrix slightly off
Im trying to rotate my cube using quaternion to matrix rotation based on arcball mouse movement. My cube is rendering, and it has movement/rotation, but it isnt simply just rotating around an axis, it is also moving in the direction of my mouse, so i think that either the data that im getting from my trackball is a bit off, or the way im transforming my quaternion into a rotation matrix is slightly off. trackball_ptov is where i translate mouse location to an arcball. mouseMotion() is where im creating the rotation matrix from the quaternion.
The entirety of my main:
#include "Angel.h"
#include <gl/glew.h>
#include <glut.h>
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
#include <iostream>
using namespace std;
#define bool int /* if system does not support bool type */
#define false 0
#define true 1
#define M_PI 3.14159265358 /* if not in math.h */
int winWidth, winHeight;
float angle = 0.0, axis[3], trans[3];
bool trackingMouse = false;
float lastPos[3] = {0.0, 0.0, 0.0};
float aspect = 1.0;
int curx, cury;
int startX, startY;
int modelInit=1;
//the program object
GLuint program = 0;
glm::mat4 model;
typedef Angel::vec4 color4;
typedef Angel::vec4 point4;
const int NumVertices = 36; //(6 faces)(2 triangles/face)(3 vertices/triangle)
point4 points[NumVertices];
color4 colors[NumVertices];
enum { Xaxis = 0, Yaxis = 1, Zaxis = 2, NumAxes = 3 };
int Axis = Xaxis;
GLuint mvpUniform;
GLuint shaderaxis;
int Index = 0;
// Vertices of a unit cube centered at origin, sides aligned with axes
point4 vertices[8]={
point4(-0.5, -0.5, 0.5, 1.0),
point4(-0.5, 0.5, 0.5, 1.0),
point4(0.5, 0.5, 0.5, 1.0),
point4(0.5, -0.5, 0.5, 1.0),
point4(-0.5, -0.5, -0.5, 1.0),
point4(-0.5, 0.5, -0.5, 1.0),
point4(0.5, 0.5, -0.5, 1.0),
point4(0.5, -0.5, -0.5, 1.0)
};
// RGBA colors
color4 vertex_colors[8] = {
color4(0.0, 0.0, 0.0, 1.0), // black
color4(1.0, 0.0, 0.0, 1.0), // red
color4(1.0, 1.0, 0.0, 1.0), // yellow
color4(0.0, 1.0, 0.0, 1.0), // green
color4(0.0, 0.0, 1.0, 1.0), // blue
color4(1.0, 0.0, 1.0, 1.0), // magenta
color4(1.0, 1.0, 1.0, 1.0), // white
color4(0.0, 1.0, 1.0, 1.0) // cyan
};
// quad generates two triangles for each face and assigns colors to the vertices
void quad(int a, int b, int c, int d) {
colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
colors[Index] = vertex_colors[b]; points[Index] = vertices[b]; Index++;
colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
colors[Index] = vertex_colors[a]; points[Index] = vertices[a]; Index++;
colors[Index] = vertex_colors[c]; points[Index] = vertices[c]; Index++;
colors[Index] = vertex_colors[d]; points[Index] = vertices[d]; Index++;
}
// generate 12 triangles: 36 vertices and 36 colors
void colorcube(void) {
quad(1, 0, 3, 2);
quad(2, 3, 7, 6);
quad(3, 0, 4, 7);
quad(6, 5, 1, 2);
quad(4, 5, 6, 7);
quad(5, 4, 0, 1);
}
// OpenGL initialization
void init(void) {
colorcube();
// Load shaders and use the resulting shader program
GLuint program = InitShader("vshader36.glsl", "fshader36.glsl");
glUseProgram(program);
// Create a vertex array object
GLuint vao;
glGenVertexArrays(1, &vao);
glBindVertexArray(vao);
// Create and initialize a buffer object
GLuint buffer;
glGenBuffers(1, &buffer);
glBindBuffer(GL_ARRAY_BUFFER, buffer);
glBufferData(GL_ARRAY_BUFFER, sizeof(points) + sizeof(colors), NULL, GL_STATIC_DRAW);
glBufferSubData(GL_ARRAY_BUFFER, 0, sizeof(points), points);
glBufferSubData(GL_ARRAY_BUFFER, sizeof(points), sizeof(colors), colors);
// set up vertex arrays
glEnableVertexAttribArray(0);
glVertexAttribPointer(0, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(0));
model = glm::translate(glm::mat4(1.0), glm::vec3(0.0, 0.0, -5.0));
glEnableVertexAttribArray(1);
glVertexAttribPointer(1, 4, GL_FLOAT, GL_FALSE, 0, BUFFER_OFFSET(sizeof(points)));
mvpUniform = glGetUniformLocation(program, "mvp");
glEnable(GL_DEPTH_TEST);
glClearColor(1.0, 1.0, 1.0, 1.0);
}
void trackball_ptov(int x, int y, int width, int height, float v[3]) {
float d, a;
/* project x, y onto a hemisphere centered within width, height , note z is up here*/
v[0] = (2.0*x - width) / width;
v[1] = (height - 2.0F*y) / height;
d = sqrt(v[0]*v[0] + v[1]*v[1]);
v[2] = cos((M_PI/2.0) * ((d < 1.0) ? d : 1.0));
a = 1.0 / sqrt(v[0]*v[0] + v[1]*v[1] + v[2]*v[2]);
v[0] *= a;
v[1] *= a;
v[2] *= a;
}
void display() {
glClear(GL_COLOR_BUFFER_BIT|GL_DEPTH_BUFFER_BIT);
glm::mat4 proj = glm::perspective(90.F, 1.F, 0.1F, 100.F);
glm::mat4 view = glm::translate(glm::mat4(1.0), glm::vec3(0.0, 0.0, 0.0)); //apply mouse translation
//view = glm::rotate(view, 0.2*mousediff.x, glm::vec3(0.0, 1.0, 0.0)); //apply mouse rotation
//view = glm::rotate(view, 0.2*mousediff.y, glm::vec3(1.0, 0.0, 0.0));
//model = glm::translate(glm::mat4(1.0), glm::vec3(0.0, 0.0, -5.0));
//glUniformMatrix4fv(mvpUniform, 1, false, glm::value_ptr(proj));
glUniformMatrix4fv(mvpUniform, 1, false, glm::value_ptr(proj*view*model));
//glUniformMatrix4fv(mvpUniform, 1, false, glm::value_ptr(model*view*proj));
glDrawArrays(GL_TRIANGLES, 0, NumVertices);
glutSwapBuffers();
}
void keyboard(unsigned char key, int x, int y) {
switch(key) {
case 033: // Escape Key
case 'q': case 'Q':
exit(EXIT_SUCCESS);
break;
}
}
void mouseButton(int button, int state, int x, int y) {
if(button==GLUT_RIGHT_BUTTON) exit(0);
/* holding down left button allows user to rotate cube */
if(button==GLUT_LEFT_BUTTON)
switch(state) {
case GLUT_DOWN:
trackingMouse = true;
startX = x;
startY = y;
curx = x;
cury = y;
trackball_ptov(x, y, 512, 512, lastPos);
break;
case GLUT_UP:
trackingMouse = false;
angle = 0.0;
break;
}
}
void mouseMotion(int x, int y) {
float curPos[3], dx, dy, dz;
/* compute position on hemisphere */
if(trackingMouse) {
/* compute the change in position on the hemisphere */
trackball_ptov(x, y, 512, 512, curPos);
dx = curPos[0] - lastPos[0];
dy = curPos[1] - lastPos[1];
dz = curPos[2] - lastPos[2];
if (dx || dy || dz) {
/* compute theta and cross product */
angle = 90.0 * sqrt(dx*dx + dy*dy + dz*dz);
axis[0] = lastPos[1]*curPos[2] - lastPos[2]*curPos[1];
axis[1] = lastPos[2]*curPos[0] - lastPos[0]*curPos[2];
axis[2] = lastPos[0]*curPos[1] - lastPos[1]*curPos[0];
/* update position */
lastPos[0] = curPos[0];
lastPos[1] = curPos[1];
lastPos[2] = curPos[2];
}
float w = angle;
float x = axis[0];
float y = axis[1];
float z = axis[2];
glm::mat4 xform = glm::mat4((1.F - (2.F * ( y*y + z*z ))),(2.F * ( x*y - z*w )),( x*z + y*w ),0.F,
(2.F * ( x*y + z*w )),(1.F - (2.F * ( x*x + z*z ))),(2.F * ( y*z - x*w )),0.F,
(2.F * ( x*z - y*w )),(2.F * ( y*z + x*w )),(1.F - (2.F * ( x*x + y*y ))),0.F,
0.F,0.F,0.F,1.F);
model = xform*model;
}
glutPostRedisplay();
}
int main(int argc, char **argv) {
glutInit(&argc, argv);
glutInitDisplayMode(GLUT_RGBA | GLUT_DOUBLE | GLUT_DEPTH);
glutInitWindowSize(512, 512);
glutCreateWindow("Color Cube");
glewInit();
init();
glutDisplayFunc(display);
glutKeyboardFunc(keyboard);
glutIdleFunc(display);
glutMouseFunc(mouseButton);
glutMotionFunc(mouseMotion);
glutMainLoop();
return 0;
}
Here is the fshader36
#version 150
in vec4 color;
out vec4 fColor;
void main()
{
fColor = color;
}
here is VSHADER
#version 330
uniform mat4 mvp;
layout(location=0) in vec4 vPosition;
layout(location=1) in vec4 vColor;
out vec4 color;
void main() {
color = vColor;
gl_Position = mvp * vPosition;
}