I have a depth texture defined as the following:
//shadow FBO and texture
depthFBO = new FrameBufferObject().create().bind();
depthTexture = new Texture2D().create().bind()
.storage2D(12, GL_DEPTH_COMPONENT32F, 4096, 4096)
.minFilter(GL_LINEAR)
.magFilter(GL_LINEAR)
.compareMode(GL_COMPARE_REF_TO_TEXTURE)
.compareFunc(GL_LEQUAL);
depthFBO.texture2D(GL_DEPTH_ATTACHMENT, GL11.GL_TEXTURE_2D, depthTexture, 0)
.checkStatus().unbind();
depthTexture.unbind();
It's written in Java/LWJGL/Own small framework, but the idea should be clear.
Then I use a fragment shader at some point to visualize the data in it (fragment's depth):
#version 430 core
layout(location = 7) uniform int screen_width;
layout(location = 8) uniform int screen_height;
layout(binding = 0) uniform sampler2D shadow_tex;
out vec4 color;
void main(void) {
vec2 tex_coords = vec2(
(gl_FragCoord.x - 100) / (screen_width / 5),
(gl_FragCoord.y - (screen_height - (screen_height / 5) - 100)) / (screen_height / 5)
);
float red_channel = texture(shadow_tex, tex_coords).r;
if (red_channel < 0.999) {
red_channel = red_channel / 2.0;
}
color = vec4(vec3(red_channel), 1.0);
}
My tex_coords
and shadow_tex
are correct, but I need some more clarification on reading out of a GL_DEPTH_COMPONENT32F
format.
I want to read the depth and I assume it is being stored being 0.0 and 1.0 in 4 bytes of float values.
So I was thinking I can use the red channel of what texture
gives me back, however I cannot see a difference in depth. Other than it not being 1.0 exactly, but somewhat lower. If I do not divide by 2.0, then everything appears white.
Note that the floor is black at some points, but that is due to a failed shadow mapping, hence why I am visualizing it - however it is temporarily set to use the normal view MVP instead of the light's, to also make sure the depth information is saved correctly.
UPDATE: The colorization of the depth value is now working correctly with the following:
#version 430 core
layout(location = 7) uniform int screen_width;
layout(location = 8) uniform int screen_height;
layout(binding = 0) uniform sampler2D shadow_tex;
out vec4 color;
float linearize_depth(float original_depth) {
float near = 0.1;
float far = 1000.0;
return (2.0 * near) / (far + near - original_depth * (far - near));
}
void main(void) {
//calculate texture coordinates, based on current dimensions and positions of the viewport
vec2 tex_coords = vec2(
(gl_FragCoord.x - 100) / (screen_width / 5),
(gl_FragCoord.y - (screen_height - (screen_height / 5) - 100)) / (screen_height / 5)
);
//retrieve depth value from the red channel
float red_channel = texture(shadow_tex, tex_coords).r;
//colorize depth value, only if there actually is an object
if (red_channel < 0.999) {
red_channel = linearize_depth(red_channel) * 4.0;
}
color = vec4(vec3(red_channel), 1.0);
}
I would still like clarification though if accessing the red component is correct to retrieve the depth value?