nuclear@8: #include <stdio.h>
nuclear@8: #include <stdlib.h>
nuclear@8: #include <string.h>
nuclear@8: #include "opengl.h"
nuclear@8: #include "mesh.h"
nuclear@8: 
nuclear@8: static void distort_texcoords(float *tc, float aspect, float lens_center_offset, float scale,
nuclear@8: 		const float *dist_factors);
nuclear@8: static float barrel_scale(float rad, const float *k);
nuclear@8: 
nuclear@8: /* let's avoid a glew dependency in the library just for this */
nuclear@8: #ifndef GL_ARRAY_BUFFER
nuclear@8: #define GL_ARRAY_BUFFER			0x8892
nuclear@8: #define GL_ELEMENT_ARRAY_BUFFER 0x8893
nuclear@8: #define GL_STATIC_DRAW			0x88E4
nuclear@8: #endif
nuclear@8: 
nuclear@8: #if !defined(GL_VERSION_1_5) || !defined(GL_GLEXT_PROTOTYPES)
nuclear@8: static void (*glGenBuffers)(GLsizei, GLuint*);
nuclear@8: static void (*glDeleteBuffers)(GLsizei, GLuint*);
nuclear@8: static void (*glBufferData)(GLenum, unsigned int, const GLvoid*, GLenum);
nuclear@8: static void (*glBindBuffer)(GLenum, GLuint);
nuclear@8: #endif
nuclear@8: 
nuclear@8: int vrimp_mesh_init(struct mesh *m)
nuclear@8: {
nuclear@8: 	m->prim = GL_TRIANGLES;
nuclear@8: 
nuclear@8: 	m->varr = 0;
nuclear@8: 	m->iarr = 0;
nuclear@8: 	m->num_verts = m->num_faces = 0;
nuclear@8: 	m->vbo = m->ibo = 0;
nuclear@8: 
nuclear@8: 	if(!glGenBuffers) {
nuclear@8: 		glGenBuffers = vrimp_glfunc("glGenBuffersARB");
nuclear@8: 		glDeleteBuffers = vrimp_glfunc("glDeleteBuffersARB");
nuclear@8: 		glBufferData = vrimp_glfunc("glBufferDataARB");
nuclear@8: 		glBindBuffer = vrimp_glfunc("glBindBufferARB");
nuclear@8: 
nuclear@8: 		if(!(glGenBuffers && glDeleteBuffers && glBufferData && glBindBuffer)) {
nuclear@8: 			fprintf(stderr, "Failed to load VBO functions\n");
nuclear@8: 			return -1;
nuclear@8: 		}
nuclear@8: 	}
nuclear@8: 
nuclear@8: 	return 0;
nuclear@8: }
nuclear@8: 
nuclear@8: void vrimp_mesh_destroy(struct mesh *m)
nuclear@8: {
nuclear@8: 	free(m->varr);
nuclear@8: 	free(m->iarr);
nuclear@8: 
nuclear@8: 	if(m->vbo) glDeleteBuffers(1, &m->vbo);
nuclear@8: 	if(m->ibo) glDeleteBuffers(1, &m->ibo);
nuclear@8: }
nuclear@8: 
nuclear@8: void vrimp_mesh_draw(struct mesh *m)
nuclear@8: {
nuclear@8: 	glEnableClientState(GL_VERTEX_ARRAY);
nuclear@8: 	glEnableClientState(GL_TEXTURE_COORD_ARRAY);
nuclear@8: 
nuclear@8: 	glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
nuclear@8: 	glVertexPointer(3, GL_FLOAT, sizeof(struct vertex), 0);
nuclear@8: 	glTexCoordPointer(2, GL_FLOAT, sizeof(struct vertex), (void*)offsetof(struct vertex, tx));
nuclear@8: 
nuclear@8: 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ibo);
nuclear@8: 	glDrawElements(GL_TRIANGLES, m->num_faces * 3, GL_UNSIGNED_INT, 0);
nuclear@8: 
nuclear@8: 	glBindBuffer(GL_ARRAY_BUFFER, 0);
nuclear@8: 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, 0);
nuclear@8: 
nuclear@8: 	glDisableClientState(GL_VERTEX_ARRAY);
nuclear@8: 	glDisableClientState(GL_TEXTURE_COORD_ARRAY);
nuclear@8: }
nuclear@8: 
nuclear@8: int vrimp_mesh_barrel_distortion(struct mesh *m, int usub, int vsub, float aspect,
nuclear@8: 		float lens_center_offset, float scale, const float *dist_factors,
nuclear@8: 		float tex_scale_x, float tex_scale_y)
nuclear@8: {
nuclear@8: 	int i, j;
nuclear@8: 	int uverts, vverts;
nuclear@8: 	int num_verts, num_quads, num_tris;
nuclear@8: 	struct vertex *varr, *vptr;
nuclear@8: 	unsigned int *iarr, *iptr;
nuclear@8: 	float du, dv;
nuclear@8: 
nuclear@8: 	uverts = usub + 1;
nuclear@8: 	vverts = vsub + 1;
nuclear@8: 
nuclear@8: 	num_verts = uverts * vverts;
nuclear@8: 	num_quads = usub * vsub;
nuclear@8: 	num_tris = num_quads * 2;
nuclear@8: 
nuclear@8: 	if(!(varr = malloc(num_verts * sizeof *varr))) {
nuclear@8: 		return -1;
nuclear@8: 	}
nuclear@8: 	if(!(iarr = malloc(num_tris * 3 * sizeof *iarr))) {
nuclear@8: 		free(varr);
nuclear@8: 		return -1;
nuclear@8: 	}
nuclear@8: 
nuclear@8: 	du = 1.0 / (float)usub;
nuclear@8: 	dv = 1.0 / (float)vsub;
nuclear@8: 
nuclear@8: 	vptr = varr;
nuclear@8: 	for(i=0; i<vverts; i++) {
nuclear@8: 		float v = (float)i * dv;
nuclear@8: 		float y = 2.0 * v - 1.0;
nuclear@8: 
nuclear@8: 		for(j=0; j<uverts; j++) {
nuclear@8: 			float u = (float)j * du;
nuclear@8: 			float x = 2.0 * u - 1.0;
nuclear@8: 			float tc[2];
nuclear@8: 			tc[0] = u;
nuclear@8: 			tc[1] = v;
nuclear@8: 
nuclear@8: 			distort_texcoords(tc, aspect, lens_center_offset, scale, dist_factors);
nuclear@8: 
nuclear@8: 			vptr->x = x;
nuclear@8: 			vptr->y = y;
nuclear@8: 			vptr->z = 0;
nuclear@8: 			vptr->tx = tc[0] * tex_scale_x;
nuclear@8: 			vptr->ty = tc[1] * tex_scale_y;
nuclear@8: 			vptr++;
nuclear@8: 		}
nuclear@8: 	}
nuclear@8: 
nuclear@8: 	iptr = iarr;
nuclear@8: 	for(i=0; i<vsub; i++) {
nuclear@8: 		for(j=0; j<usub; j++) {
nuclear@8: 			*iptr++ = i * uverts + j;
nuclear@8: 			*iptr++ = (i + 1) * uverts + j;
nuclear@8: 			*iptr++ = (i + 1) * uverts + (j + 1);
nuclear@8: 
nuclear@8: 			*iptr++ = i * uverts + j;
nuclear@8: 			*iptr++ = (i + 1) * uverts + (j + 1);
nuclear@8: 			*iptr++ = i * uverts + (j + 1);
nuclear@8: 		}
nuclear@8: 	}
nuclear@8: 
nuclear@8: 	glGenBuffers(1, &m->vbo);
nuclear@8: 	glGenBuffers(1, &m->ibo);
nuclear@8: 	glBindBuffer(GL_ARRAY_BUFFER, m->vbo);
nuclear@8: 	glBufferData(GL_ARRAY_BUFFER, num_verts * sizeof *varr, varr, GL_STATIC_DRAW);
nuclear@8: 	glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, m->ibo);
nuclear@8: 	glBufferData(GL_ELEMENT_ARRAY_BUFFER, num_tris * 3 * sizeof *iarr, iarr, GL_STATIC_DRAW);
nuclear@8: 
nuclear@8: 	m->prim = GL_TRIANGLES;
nuclear@8: 	m->num_verts = num_verts;
nuclear@8: 	m->num_faces = num_tris;
nuclear@8: 	return 0;
nuclear@8: }
nuclear@8: 
nuclear@8: static void distort_texcoords(float *tc, float aspect, float lens_center_offset, float scale,
nuclear@8: 		const float *dist_factors)
nuclear@8: {
nuclear@8: 	/* map tc [0, 1] -> [-1, 1] */
nuclear@8: 	float ptx = tc[0] * 2.0 - 1.0;
nuclear@8: 	float pty = tc[1] * 2.0 - 1.0;
nuclear@8: 	float rad;
nuclear@8: 
nuclear@8: 	ptx += lens_center_offset * 2.0;
nuclear@8: 	pty /= aspect;	/* correct for aspect ratio */
nuclear@8: 
nuclear@8: 	rad = barrel_scale(ptx * ptx + pty * pty, dist_factors);
nuclear@8: 	ptx *= rad;	/* scale the point by the computer distortion radius */
nuclear@8: 	pty *= rad;
nuclear@8: 
nuclear@8: 	ptx /= scale;
nuclear@8: 	pty /= scale;
nuclear@8: 
nuclear@8: 	pty *= aspect;
nuclear@8: 	ptx -= lens_center_offset * 2.0;
nuclear@8: 
nuclear@8: 	/* map back to range [0, 1] */
nuclear@8: 	tc[0] = ptx * 0.5 + 0.5;
nuclear@8: 	tc[1] = pty * 0.5 + 0.5;
nuclear@8: }
nuclear@8: 
nuclear@8: static float barrel_scale(float rad, const float *k)
nuclear@8: {
nuclear@8: 	float radsq = rad * rad;
nuclear@8: 	float radquad = radsq * radsq;
nuclear@8: 	return k[0] + k[1] * radsq + k[2] * radquad + k[3] * radquad * radsq;
nuclear@8: }