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OpenGL Problems getting shadow coordinates and using a shadow map with deferred rendering

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Posted (edited)

I am currently trying to implement shadow mapping into my project , but although i can render my depth map to the screen and it looks okay , when i sample it with shadowCoords there is no shadow.

Here is my light space matrix calculation

mat4x4 lightViewMatrix;

vec3 sun_pos = {SUN_OFFSET  * the_sun->direction[0],
                SUN_OFFSET  * the_sun->direction[1],
                SUN_OFFSET  * the_sun->direction[2]};



I will tweak the values for the size and frustum of the shadow map, but for now i just want to draw shadows around the player position

the_sun->direction is a normalized vector so i multiply it by a constant to get the position.

player->pos is the camera position in world space

the light projection matrix is calculated like this:


Shadow vertex shader:

uniform mat4 light_space_matrix;

 void main()
     gl_Position = light_space_matrix * transfMatrix * vec4(position, 1.0f); 

Shadow fragment shader:

out float fragDepth;
void main()
    fragDepth = gl_FragCoord.z;

I am using deferred rendering so i have all my world positions in the g_positions buffer

My shadow calculation in the deferred fragment shader:

float get_shadow_fac(vec4 light_space_pos)
    vec3 shadow_coords = light_space_pos.xyz / light_space_pos.w;
    shadow_coords      = shadow_coords * 0.5 + 0.5;

    float closest_depth = texture(shadow_map, shadow_coords.xy).r;
    float current_depth = shadow_coords.z;

    float shadow_fac = 1.0;

    if(closest_depth < current_depth)
       shadow_fac   = 0.5;

    return shadow_fac;

I call the function like this:

get_shadow_fac(light_space_matrix * vec4(position,1.0));

Where position is the value i got from sampling the g_position buffer

Here is my depth texture (i know it will produce low quality shadows but i just want to get it working for now):

sorry because of the compression , the black smudges are trees ... https://i.stack.imgur.com/T43aK.jpg

EDIT: Depth texture attachment:

glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, fbo->depthTexture, 0);
Edited by Andrija
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I found out what the problem was , my g_positions buffers texture had the internal format of GL_RGBA8 and that is too small to hold positions in world space


so when i changed to


shadows appeared :D

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I was just trying to render shadows in a box around the player , now that the shadows are appearing i am implementing a shadow frustum that encloses the player frustum

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