我正在学习 OpenGL 的基础知识,并尝试使用正交投影来平移三角形。我没有看到我所期望的,我做错了什么?
我的顶点缓冲区:
Vertices[0] = Vector3f(-1.0f, -1.0f, 0.0f);
Vertices[1] = Vector3f(1.0f, -1.0f, 0.0f);
Vertices[2] = Vector3f(-1.0f, 1.0f, 0.0f);
glGenBuffers(1, &VBO);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glBufferData(GL_ARRAY_BUFFER, sizeof(Vertices), Vertices, GL_STATIC_DRAW);
顶点着色器:
#version 330
layout (location = 0) in vec3 Position;
uniform mat4 gMVP;
void main()
{
gl_Position = gMVP * vec4(Position, 1.0);
}
MVP计算和渲染:
glm::mat4 p = glm::ortho(-2.0f, 2.0f, -2.0f, 2.0f, -2.0f, 2.0f);
glm::mat4 v = glm::lookAt(glm::vec3(0,0,1), glm::vec3(0,0,0), glm::vec3(0,1,0));
glm::mat4 m = glm::translate(glm::mat4(1.0f), glm::vec3(0.5f, 0.0f, 0.0f));
glm::mat4 MVP = p * v * m;
glUniformMatrix4fv(gMVPLocation, 1, GL_TRUE, &MVP[0][0]);
glEnableVertexAttribArray(0);
glBindBuffer(GL_ARRAY_BUFFER, VBO);
glVertexAttribPointer(0, 3, GL_FLOAT, GL_FALSE, 0, 0);
glDrawArrays(GL_TRIANGLES, 0, 3);
glDisableVertexAttribArray(0);
glutSwapBuffers();
结果:
它不应该沿着X轴向右移动吗?
最佳答案
glUniformMatrix4fv
的第三个参数导致矩阵在设置为uniform时会转置。 OpenGL Mathematics (GLM)以相同的方式构造矩阵,就像 GLSL 构造 mat4
类型的变量一样。
当矩阵设置为uniform时,不必转置:
glUniformMatrix4fv(gMVPLocation, 1, GL_TRUE, &MVP[0][0]);
glUniformMatrix4fv(gMVPLocation, 1, GL_FALSE, &MVP[0][0]);
在 GLSL 中, vector 必须从右侧乘以矩阵。请参阅GLSL Programming/Vector and Matrix Operations
关于c++ - 翻译过程中 MVP 行为异常,我们在Stack Overflow上找到一个类似的问题: https://stackoverflow.com/questions/60591738/