scummvm/graphics/tinygl/matrix.cpp

#include "engine/tinygl/zgl.h"

void gl_print_matrix(const float *m) {
	int i;

	for (i = 0; i < 4; i++) {
		fprintf(stderr, "%f %f %f %f\n", m[i], m[4 + i], m[8 + i], m[12 + i]);
	}
}

static inline void gl_matrix_update(GLContext *c) {
	c->matrix_model_projection_updated = (c->matrix_mode <= 1);
}

void glopMatrixMode(GLContext *c, TGLParam *p) {
	int mode = p[1].i;
	switch (mode) {
	case TGL_MODELVIEW:
		c->matrix_mode = 0;
		break;
	case TGL_PROJECTION:
		c->matrix_mode = 1;
		break;
	case TGL_TEXTURE:
		c->matrix_mode = 2;
		break;
	default:
		assert(0);
	}
}

void glopLoadMatrix(GLContext *c, TGLParam *p) {
	M4 *m;
	int i;
  
	TGLParam *q;

	m = c->matrix_stack_ptr[c->matrix_mode];
	q = p + 1;

	for (i = 0; i < 4; i++) {
		m->m[0][i] = q[0].f;
		m->m[1][i] = q[1].f;
		m->m[2][i] = q[2].f;
		m->m[3][i] = q[3].f;
		q += 4;
	}

	gl_matrix_update(c);
}

void glopLoadIdentity(GLContext *c, TGLParam *) {
	gl_M4_Id(c->matrix_stack_ptr[c->matrix_mode]);

	gl_matrix_update(c);
}

void glopMultMatrix(GLContext *c, TGLParam *p) {
	M4 m;
	int i;

	TGLParam *q;
	q = p + 1;

	for (i = 0; i < 4; i++) {
		m.m[0][i] = q[0].f;
		m.m[1][i] = q[1].f;
		m.m[2][i] = q[2].f;
		m.m[3][i] = q[3].f;
		q += 4;
	}

	gl_M4_MulLeft(c->matrix_stack_ptr[c->matrix_mode], &m);

	gl_matrix_update(c);
}


void glopPushMatrix(GLContext *c, TGLParam *) {
	int n = c->matrix_mode;
	M4 *m;

	assert((c->matrix_stack_ptr[n] - c->matrix_stack[n] + 1) < c->matrix_stack_depth_max[n]);

	m = ++c->matrix_stack_ptr[n];
  
	gl_M4_Move(&m[0], &m[-1]);

	gl_matrix_update(c);
}

void glopPopMatrix(GLContext *c, TGLParam *) {
	int n=c->matrix_mode;

	assert(c->matrix_stack_ptr[n] > c->matrix_stack[n]);
	c->matrix_stack_ptr[n]--;
	gl_matrix_update(c);
}

void glopRotate(GLContext *c, TGLParam *p) {
	M4 m;
	float u[3];
	float angle;
	int dir_code;

	angle = (float)(p[1].f * LOCAL_PI / 180.0);
	u[0] = p[2].f;
	u[1] = p[3].f;
	u[2] = p[4].f;

	// simple case detection
	dir_code = ((u[0] != 0)<<2) | ((u[1] != 0)<<1) | (u[2] != 0);

	switch (dir_code) {
	case 0:
		gl_M4_Id(&m);
		break;
	case 4:
		if (u[0] < 0) angle=-angle;
			gl_M4_Rotate(&m,angle,0);
		break;
	case 2:
		if (u[1] < 0) angle=-angle;
			gl_M4_Rotate(&m,angle,1);
		break;
	case 1:
		if (u[2] < 0) angle=-angle;
			gl_M4_Rotate(&m,angle,2);
		break;
	default:
		{
			float cost, sint;

			// normalize vector
			float len = u[0] * u[0] + u[1] * u[1] + u[2] * u[2];
			if (len == 0.0f)
				return;
			len = 1.0f / sqrt(len);
			u[0] *= len;
			u[1] *= len;
			u[2] *= len;

			// store cos and sin values
			cost = cos(angle);
			sint = sin(angle);

			// fill in the values
			m.m[3][0] = m.m[3][1] = m.m[3][2] = m.m[0][3] = m.m[1][3] = m.m[2][3] = 0.0f;
			m.m[3][3] = 1.0f;

			// do the math
			m.m[0][0] = u[0] * u[0] + cost * (1 - u[0] * u[0]);
			m.m[1][0] = u[0] * u[1] * (1 -cost) - u[2] * sint;
			m.m[2][0] = u[2] * u[0] * (1 -cost) + u[1] * sint;
			m.m[0][1] = u[0] * u[1] * (1 -cost) + u[2] * sint;
			m.m[1][1] = u[1] * u[1] + cost * (1 - u[1] * u[1]);
			m.m[2][1] = u[1] * u[2] * (1 - cost) - u[0] * sint;
			m.m[0][2] = u[2] * u[0] * (1 - cost) - u[1] * sint;
			m.m[1][2] = u[1] * u[2] * (1 - cost) + u[0] * sint;
			m.m[2][2] = u[2] * u[2] + cost * (1 - u[2] * u[2]);
		}
	}

	gl_M4_MulLeft(c->matrix_stack_ptr[c->matrix_mode], &m);

	gl_matrix_update(c);
}

void glopScale(GLContext *c, TGLParam *p) {
	float *m;
	float x = p[1].f, y = p[2].f, z = p[3].f;

	m = &c->matrix_stack_ptr[c->matrix_mode]->m[0][0];

	m[0] *= x;  m[1] *= y;  m[2]  *= z;
	m[4] *= x;  m[5] *= y;  m[6]  *= z;
	m[8] *= x;  m[9] *= y;  m[10] *= z;
	m[12] *= x;  m[13] *= y;  m[14] *= z;
	gl_matrix_update(c);
}

void glopTranslate(GLContext *c, TGLParam *p) {
	float *m;
	float x = p[1].f, y = p[2].f, z = p[3].f;

	m = &c->matrix_stack_ptr[c->matrix_mode]->m[0][0];

	m[3] = m[0] * x + m[1] * y + m[2]  * z + m[3];
	m[7] = m[4] * x + m[5] * y + m[6]  * z + m[7];
	m[11] = m[8] * x + m[9] * y + m[10] * z + m[11];
	m[15] = m[12] * x + m[13] * y + m[14] * z + m[15];

	gl_matrix_update(c);
}

void glopFrustum(GLContext *c, TGLParam *p) {
	float *r;
	M4 m;
	float left = p[1].f;
	float right = p[2].f;
	float bottom = p[3].f;
	float top = p[4].f;
	float nearp = p[5].f;
	float farp = p[6].f;
	float x, y, A, B, C, D;

	x = (float)((2.0 * nearp) / (right - left));
	y = (float)((2.0 * nearp) / (top - bottom));
	A = (right + left) / (right - left);
	B = (top + bottom) / (top - bottom);
	C = -(farp + nearp) / (farp - nearp);
	D = (float)(-(2.0 * farp * nearp) / (farp - nearp));

	r = &m.m[0][0];
	r[0] = x; r[1] = 0; r[2] = A; r[3] = 0;
	r[4] = 0; r[5] = y; r[6] = B; r[7] = 0;
	r[8] = 0; r[9] = 0; r[10] = C; r[11] = D;
	r[12] = 0; r[13] = 0; r[14] =- 1; r[15] = 0;

	gl_M4_MulLeft(c->matrix_stack_ptr[c->matrix_mode], &m);

	gl_matrix_update(c);
}