OpenGL gluLookat not working with shaders on - c++

Question

When i want to use gluLookat and have the shaders on it doesnt move the "camera" when i turn the shaders off it works correctly.
Is there something missing in my shaders, i cant figure out what.
void display(void)
{
glClear(GL_COLOR_BUFFER_BIT);
glClearColor(0.8, 0.8, 0.8, 0);
glMatrixMode(GL_MODELVIEW);
glLoadIdentity();
gluLookAt(0.5,0,1,0.5,0,0,0,1,0);
glColor3f(0, 0, 0);
glDrawArrays(GL_TRIANGLES, 0, 6);
glDrawArrays(GL_LINES, 6, 6);
glDrawArrays(GL_TRIANGLES, 12,6);
glDrawArrays(GL_LINES, 18, 4);
glDrawArrays(GL_TRIANGLES, 22, 6);
glColor3f(1, 0.7, 0);
glDrawArrays(GL_TRIANGLES, 28, 6);
glFlush();
}
Vertex Shader:
#version 450 core // 420, 330 core , compatibility
in vec4 position
out vec4 Color;
void main()
{
gl_Position = position;
}
Fragment Shader:
#version 450 core // 420, 330 core , compatibility
in vec4 Color;
layout(location=0) out vec4 fColor;
void main()
{
fColor = vec4(0,0,0,0);
}
Move the "camera" to where i want it to be with shaders on

Answer 1

When you use a shader program, then the vertex coordinate attributes are not magically processed, by the current matrices. The shader program has to do the transformations of the vertex coordinates.
You've 2 possibilities, either you use a compatibility profile context and use a lower glsl version (e.g. 1.10).
Then you can use the built in uniform gl_ModelViewProjectionMatrix (see GLSL 1.10 secification) and the fixed function matrix stack will work:
#version 110
attribute vec4 position
// varying vec4 Color;
void main()
{
// ...
gl_Position = gl_ModelViewProjectionMatrix * position;
}
But note this is deprecated since decades. See Fixed Function Pipeline and Legacy OpenGL.
I recommend to use a library like OpenGL Mathematics to calculate the view matrix by lookAt() and a uniform variable:
#version 450 core // 420, 330 core , compatibility
in vec4 position
// out vec4 Color;
layout(location = 7) uniform mat4 view_matrix;
void main()
{
gl_Position = view_matrix * position;
}
#include <glm/glm.hpp>
#include <glm/gtc/matrix_transform.hpp>
#include <glm/gtc/type_ptr.hpp>
// [...]
{
// [...]
glUseProgram(program);
glm::mat4 view = glm::lookAt(
glm::vec3(0.5f,0.0f,1.0f), glm::Vec3(0.5f,0.0f,0.0f), glm::Vec3(0.0f,1.0f,0.0f));
glUniformMatrix4fv(7, 1, GL_FALSE, glm::value_ptr(view);
// [...]
}
The uniform location is set explicite by a Layout qualifier (location = 7).
glUniformMatrix4fv sets the value of the uniform at the specified location in the default uniform block. This has to be done after the progroam was installed by glUseProgram.