我正在尝试制作一个简单的 4x4 矩阵类。数据(float
(是一个单维数组,我使用此代码来存储数字,就好像它是一个网格一样。
const inline int ind1(short x, short y) { // Convert coords to spot on linear array, uses SIZE
return x * (SIZE >> 2) + y;
}
这部分在 .h 文件中
float *data;
这些都在.cpp
Mat::Mat() {
define();
diagDefine(1.0f);
}
void Mat::define() {
data = new float[SIZE];
for (int x = 0; x < SIZE >> 2; x++) {
for (int y = 0; y < SIZE >> 2; y++) {
data[ind1(x, y)] = 0;
}
}
}
void Mat::diagDefine(float nval) {
data[ind1(0, 0)] = nval;
data[ind1(1, 1)] = nval;
data[ind1(2, 2)] = nval;
data[ind1(3, 3)] = nval;
}
问题是,当我尝试将矩阵乘以我在顶点着色器中的位置时,三角形或我正在绘制的任何内容都会消失。
我的课程有正交、透视、平移、旋转和缩放。
Mat Mat::getOrthographic(float left, float right, float top, float bottom, float near, float far) {
Mat newmat;
newmat.data[ind1(0, 0)] = 2.0f / (right - left);
newmat.data[ind1(1, 1)] = 2.0f / (top - bottom);
newmat.data[ind1(2, 2)] = 2.0f / (near - far);
newmat.data[ind1(0, 3)] = (left + right) / (left - right);
newmat.data[ind1(1, 3)] = (bottom + top) / (bottom - top);
newmat.data[ind1(2, 3)] = (far + near) / (far - near);
return newmat;
}
Mat Mat::getPerspective(float fov, float aspectratio, float near, float far) {
Mat newmat;
newmat.data[ind1(0, 0)] = (1.0f / tan((0.5f * fov) * (3.141519 / 180.0f))) / aspectratio;
newmat.data[ind1(1, 1)] = 1.0f / tan((0.5f * fov) * (3.141519 / 180.0f));
newmat.data[ind1(2, 2)] = (near + far) / (near - far);
newmat.data[ind1(3, 2)] = -1.0f;
newmat.data[ind1(2, 3)] = (2.0f * near * far) / (near - far);
return newmat;
}
Mat Mat::getTranslation(Vec3f &vec) {
Mat newmat;
newmat.data[ind1(0, 3)] = vec.x;
newmat.data[ind1(1, 3)] = vec.y;
newmat.data[ind1(2, 3)] = vec.z;
return newmat;
}
Mat Mat::getRotation(double angle, Vec3f &vec) {
Mat newmat;
float s = sin(angle);
float c = cos(angle);
newmat.data[ind1(0, 0)] = vec.x * (1.0f - c) + c;
newmat.data[ind1(1, 0)] = vec.y * vec.x * (1.0f - c) + vec.z * s;
newmat.data[ind1(2, 0)] = vec.x * vec.z * (1.0f - c) - vec.y * s;
newmat.data[ind1(0, 1)] = vec.x * vec.y * (1.0f - c) - vec.z * s;
newmat.data[ind1(1, 1)] = vec.y * (1.0f - c) + c;
newmat.data[ind1(2, 1)] = vec.y * vec.z * (1.0f - c) + vec.x * s;
newmat.data[ind1(0, 2)] = vec.x * vec.z * (1.0f - c) + vec.y * s;
newmat.data[ind1(1, 2)] = vec.y * vec.z * (1.0f - c) - vec.x * s;
newmat.data[ind1(2, 2)] = vec.z * (1.0f - c) + c;
return newmat;
}
Mat Mat::getScale(Vec3f &vec) {
Mat newmat;
newmat.data[ind1(0, 0)] = vec.x;
newmat.data[ind1(1, 1)] = vec.y;
newmat.data[ind1(2, 2)] = vec.z;
return newmat;
}
顶点代码
#version 330
layout(location = 0) in vec3 pos;
uniform mat4 view_mat;
void main() {
gl_Position = view_mat * vec4(pos, 1.0);
}
最后,这是我将数据发送到着色器的方式。
// In the matrix file
float *getRawDataAsArray() { return data; }
// In the shader.h file
void Shader::GL_SET_UNIFORM_MATRIX(const char *name, Mat matrix) {
GLint location = glGetUniformLocation(program, name);
if(location != -1) {
glUniformMatrix4x2fv(location, 1, GL_FALSE, matrix.getRawDataAsArray());
}
}
// In the main.cpp (sh is shader object that contained the GET_UNIFORM_MATRIX
sh.GL_SET_UNIFORM_MATRIX("view_mat", sod2::Mat::getRotation(3.141519 / 2, 0, 0, 1));
sh.GL_SET_UNIFORM_4f("color", 0.0, 1.0, 0.0, 1.0);
最后说明:我的着色器确实可以完美编译。当我运行它与矩阵没有任何关系时,它可以完美运行。(处理颜色或修改位置(。谢谢
代码中有 2 个问题:
您使用了错误的glUniform*
函数在函数Shader::GL_SET_UNIFORM_MATRIX
中设置view_mat
均匀。glUniformMatrix4fv
为 4*4* 矩阵提交 16 个浮点数,glUniformMatrix4x2fv
为 4*2 矩阵提交 8 个浮点数。
请参阅glUniform
。
进一步参见 OpenGL 着色语言 4.6, 5.4.2 向量和矩阵构造函数,第 101 页:
要通过指定向量或标量来初始化矩阵,将按列主顺序将组件分配给矩阵元素。
mat4(float, float, float, float, // first column float, float, float, float, // second column float, float, float, float, // third column float, float, float, float); // fourth column
但是您的矩阵是按行主顺序设置的:
const inline int ind1(short x, short y) {
return x * (SIZE >> 2) + y;
}
必须更改ind1
函数才能解决此问题:
const inline int ind1(short x, short y) {
return y * (SIZE >> 2) + x;
}
或者,当矩阵设置为一致变量时,必须将其转置:
glUniformMatrix4fv(
location,
1,
GL_TRUE, // <----------------- transpose
matrix.getRawDataAsArray());
或者向量必须从左边乘到矩阵:
gl_Position = vec4(pos, 1.0) * view_mat;