三角面索引结构体
存储绘制三角面需要的三角形顶点索引值。
typedef struct
{
int a;
int b;
int c;
} face_t;
在triangle.h中声明三角面结构体。
三角形结构体
存储屏幕空间三角形的三个顶点。
typedef struct
{
vec2_t points[3];
} triangle_t;
再声明一个三角形结构体存储投影到屏幕上的信息。
立方体模型数据
一个立方体由八个顶点六个面组成，接下来我们手动写出这些数据。
#define N_MESH_VERTICES 8
extern vec3_t mesh_vertices[N_MESH_VERTICES];
#define N_MESH_FACES (6 * 2) // 6 cube faces, 2 triangles per frame
extern face_t mesh_faces[N_MESH_FACES];
现在mesh.h文件中定义8个定点，6个三角面。
vec3_t mesh_vertices[N_MESH_VERTICES] = {
{ .x = -1, .y = -1, .z = -1}, // 1
{ .x = -1, .y = 1, .z = -1}, // 2
{ .x = 1, .y = 1, .z = -1}, // 3
{ .x = 1, .y = -1, .z = -1}, // 4
{ .x = 1, .y = 1, .z = 1}, // 5
{ .x = 1, .y = -1, .z = 1}, // 6
{ .x = -1, .y = 1, .z = 1}, // 7
{ .x = -1, .y = -1, .z = 1}, // 8
};
face_t mesh_faces[N_MESH_FACES] = {
// front
{.a = 1, .b = 2, .c = 3},
{.a = 1, .b = 3, .c = 4},
//right
{.a = 4, .b = 3, .c = 5},
{.a = 4, .b = 5, .c = 6},
//back
{.a = 6, .b = 5, .c = 7},
{.a = 6, .b = 7, .c = 8},
//left
{.a = 8, .b = 7, .c = 2},
{.a = 8, .b = 2, .c = 1},
//top
{.a = 2, .b = 7, .c = 5},
{.a = 2, .b = 5, .c = 3},
//bottom
{.a = 6, .b = 8, .c = 1},
{.a = 6, .b = 1, .c = 4},
};
在mesh.c中写入立方体的具体信息。
立方体模型应用旋转并从模型空间转换到相机空间再转到屏幕空间
cube_rotation.x += 0.01;
cube_rotation.y += 0.01;
cube_rotation.z += 0.01;
for (int i = 0; i < N_MESH_FACES; i++)
{
face_t mesh_face = mesh_faces[i];
vec3_t face_vertices[3];
face_vertices[0] = mesh_vertices[mesh_face.a - 1];
face_vertices[1] = mesh_vertices[mesh_face.b - 1];
face_vertices[2] = mesh_vertices[mesh_face.c - 1];
triangle_t projected_triangle;
// Loop all three vertices of this current face and apply transformations
for (int j = 0; j < 3; j++)
{
vec3_t transformed_vertex = face_vertices[j];
transformed_vertex = vec3_rotate_x(transformed_vertex, cube_rotation.x);
transformed_vertex = vec3_rotate_y(transformed_vertex, cube_rotation.y);
transformed_vertex = vec3_rotate_z(transformed_vertex, cube_rotation.z);
// Translate the vertex away from the camera
transformed_vertex.z -= camera_position.z;
// Project the current vertex
vec2_t projected_point = project(transformed_vertex);
// Scale and translate the projected points to the middle of the screen
projected_point.x += (window_width / 2);
projected_point.y += (window_height / 2);
projected_triangle.points[j] = projected_point;
}
// Save the projected triangle in the array of triangles to render
triangles_to_renderer[i] = projected_triangle;
}
遍历每一个三角面，取出他们的三个顶点对每一个顶点进行旋转，投影到摄像机空间，转换到屏幕空间，变换到屏幕中间。
