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Vilem Otte

OpenGL [OpenGL/GLSL]Weird deferred shading bug

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Hello,

right now I'm trying to write OpenGL/GLSL fallback for my raytracer, and I got stuck with reflections - it must be position from depth reconstruction stuff (this worked with RGB32F on positions, but switching to R32F depth killed it (I just wanted 64 bits per pixel less :( ) ... and I'm trying to solve this for about 6 hours without success :( ).
Here is thing, I'm trying to create water reflections (with shadows, and such) inside them, here are my vertex and fragment shaders of MRTs:


// Vertex shader
#version 150
#define GL_core_profile 1
#extension GL_EXT_gpu_shader4 : enable
#extension GL_ARB_shader_texture_lod : enable

uniform mat4 Gpu_ModelViewMatrix;
uniform mat4 Gpu_FlippingMatrix;
uniform mat4 Gpu_ProjectionMatrix;
uniform mat3 Gpu_NormalMatrix;

in vec3 Gpu_Vertex;
in vec3 Gpu_Normal;
in vec4 Gpu_MultiTexCoord0;
in vec4 Gpu_MultiTexCoord1;

out vec3 vert_vout;
out vec3 norm_vout;
out vec2 texCoord_vout;
out vec3 tangent_vout;
out vec3 bitangent_vout;

void main()
{
vert_vout = vec3(Gpu_ModelViewMatrix * vec4(Gpu_Vertex, 1.0));
norm_vout = Gpu_NormalMatrix * Gpu_Normal;
tangent_vout = Gpu_NormalMatrix * Gpu_MultiTexCoord1.xyz;
bitangent_vout = Gpu_NormalMatrix * normalize(cross(Gpu_Normal, Gpu_MultiTexCoord1.xyz));
texCoord_vout = vec2(Gpu_MultiTexCoord0.x, 1.0 - Gpu_MultiTexCoord0.y);

gl_Position = Gpu_ProjectionMatrix * (Gpu_ModelViewMatrix * Gpu_FlippingMatrix) * vec4(Gpu_Vertex, 1.0);
}

// Fragment shader
#version 150
#define GL_core_profile 1
#extension GL_EXT_gpu_shader4 : enable

precision highp float;

uniform mat4 Gpu_ModelViewMatrix;
uniform mat4 Gpu_ProjectionMatrix;
uniform mat3 Gpu_NormalMatrix;

uniform sampler2D buffer_diffuse;
uniform sampler2D buffer_normals;

uniform float Glossiness;
uniform float Anisotropy;

in vec3 vert_vout;
in vec3 norm_vout;
in vec2 texCoord_vout;
in vec3 tangent_vout;
in vec3 bitangent_vout;

out vec4 Gpu_FragColor[3];

void main()
{
vec3 vertex = vert_vout;
float depth = vertex.z * -1.0;

vec4 diffuseTex = texture(buffer_diffuse, texCoord_vout);

mat3 tangentFrame = mat3(normalize(tangent_vout), -normalize(bitangent_vout), norm_vout);
vec3 normalTex = texture(buffer_normals, texCoord_vout).xyz;
normalTex = normalTex * 2.0 - 1.0;
vec3 normal_vs = normalize(tangentFrame * normalTex);

gl_FragDepth = log(1.0 * depth + 1.0) / log(1.0 * 10000.0 + 1.0) * 1.0;
Gpu_FragColor[0] = vec4(depth, 0.0, 0.0, 1.0);
Gpu_FragColor[1] = vec4(normal_vs.xyz * 0.5 + 0.5, Anisotropy);
Gpu_FragColor[2] = vec4(diffuseTex.xyz, Glossiness);
}


Strange thing is, as long as Gpu_FlippingMatrix is identity, everything works fine, and as soon as it is flipped (e.g. scaled by 1, -1, 1 factor) all shadows are down and are definitely not correct. Although as I'm using depth variable from which I'm reconstructing position this way:


float depth_tex = texture(buffer_depth, texCoord_vout).x;
float fovy = radians(45.0);
float invFocalLenX = tan(fovy * 0.5) * aspect;
float invFocalLenY = tan(fovy * 0.5);
vec2 uv = texCoord_vout * 2.0 - 1.0;
vec3 position = vec3(uv * vec2(invFocalLenX, invFocalLenY) * depth_tex, -depth_tex);


The gl_Position should not affect it at all (it should just flip all vertices around plane (currently at height = 0.0, with normal 0.0 1.0 0.0), but it does! Is this AMD driver bug ? Well maybe, but I think it is just some bad variable here and/or there :(

Can anyone see issue I just don't get?

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