# OpenGL Shadows problems

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Hey guys, I worked long time ago in shadows but I left it because I couldn't find the problem I still have. I've been following this tutorial and I adapted it on my project but when I render everything I'm having weird issues I don't know why. As you can see in this pic the shadow projection is well calculated from the shader etc but you also can see that the back and front faces of both cubes are getting also weird shadow and also the shadow is repeated among the "terrain". This last problem is because of GL_REPEAT but if I use others parameters to create the texture it's worst... I tried using GL_CULLFACE to remove the weird shadows in the cubes but doesn't work. I'll leave the code here:


#include "../stdafx.h"
#include "Main.h"
#include "../Renderer/Renderer.h"
#include "../GLUtils/GLUtils.h"
#include "../Camera/Camera.h"
#include "../Audio/Audio.h"
#include "../Physics/Physics.h"
#include "../Skybox/Skybox.h"
#include "../Lighting/LightManager.h"
#include "../Entity/Entity.h"
#include "../Editor/Editor.h"
#include "../NativeGeometry/NativeGeometry.h"
#include "../Textures/TextureManager.h"
#include "../RenderTargets/RenderTargets.h"
#include "../ParticleSystem/ParticleSystem.h"
#include "../CEV/CEV.h"
#include "../Timers/Timers.h"
#include "../LUA/LuaManager.h"
#include "../LUA/EventManager.h"
#include "../LUA/EventArguments.h"
#include "../ColShapes/ColShapes.h"
#include "../KeyCode/Keycode.h"

int WINAPI WinMain(HINSTANCE hInstance, HINSTANCE hPrevInstance, LPSTR lpCmdLine, int nShowCmd)
{
//CoInitializeEx(nullptr, COINIT_MULTITHREADED);  //wtf is this xd

Console.reset(new CConsole());
Console->AllocateConsole();

Renderer = std::make_unique<CRenderer>();
ColShapeManager = std::make_unique<CColShapeManager>();
Physics = std::make_unique<CPhysics>();
EventArguments = std::make_unique<CEventsArguments>();
LuaManager = std::make_unique<CLuaManager>();
EventManager = std::make_unique<CEventManager>();
KeyCode = std::make_unique<CKeyCode>();
RenderTargetManager = std::make_unique<CRenderTargetManager>();
TextureManager = std::make_unique<CTextureManager>();
EntityManager = std::make_unique<CEntityManager>();
FogManager = std::make_unique<CFogManager>();
LightManager = std::make_unique<CLightManager>();
Skybox = std::make_unique<CSkybox>();
Camera = std::make_unique<CCamera>(glm::vec3(10, 10, 10));
CEAudio = std::make_unique<CAEngine>();
GLUtils = std::make_unique<CGLUtils>();

if (!Renderer->CreateGLWindow(1920 / 2 - (1280 / 3) + 200, 1080 / 2 - (800 / 2), 1600, 1200, 16, false))
return 0;

Renderer.release();
ColShapeManager.release();
Physics.release();
EventArguments.release();
LuaManager.release();
EventManager.release();
KeyCode.release();
RenderTargetManager.release();
TextureManager.release();
EntityManager.release();
FogManager.release();
LightManager.release();
Skybox.release();
Camera.release();
CEAudio.release();
GLUtils.release();

return 0;
}

bool first = true;

BOOL DrawGLScene()
{
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT | GL_STENCIL_BUFFER_BIT);

static GLuint depthMapFBO;
static GLuint SHADOW_WIDTH = 2048, SHADOW_HEIGHT = 2048;
static GLuint depthMap;
if (first)
{
glGenFramebuffers(1, &depthMapFBO);

glGenTextures(1, &depthMap);
glBindTexture(GL_TEXTURE_2D, depthMap);
glTexImage2D(GL_TEXTURE_2D, 0, GL_DEPTH_COMPONENT, SHADOW_WIDTH, SHADOW_HEIGHT, 0, GL_DEPTH_COMPONENT, GL_FLOAT, NULL);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MIN_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_MAG_FILTER, GL_NEAREST);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_S, GL_REPEAT);
glTexParameteri(GL_TEXTURE_2D, GL_TEXTURE_WRAP_T, GL_REPEAT);

glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
glFramebufferTexture2D(GL_FRAMEBUFFER, GL_DEPTH_ATTACHMENT, GL_TEXTURE_2D, depthMap, 0);
glDrawBuffer(GL_NONE);
glBindFramebuffer(GL_FRAMEBUFFER, 0);

first = false;
}

//SKYBOX RENDERING, LIGHT, FOG, CAMERA UPDATE & VIEWMATRIX UPDATE
Renderer->MainProgram.Start();
Camera->Update();
Renderer->SetViewMatrices();
Skybox->RenderSkybox();
LightManager->SetUpAmbientColor();
FogManager->RenderFog();

for (int i = 0; i < RenderTargetManager->GetRenderTargets(); i++)
{
CRenderTarget* RT = RenderTargetManager->GetRenderTarget(i);
if (RT)
{
RT->Bind();
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);
RT->UpdateTrans();
Skybox->RenderSkybox();
RenderTargetManager->BackToNormalRenderer();
}
}

static float xx = 0, yy = 3.f, zz = 0;
{
xx += 0.1f;
}
{
xx -= 0.1f;
}
{
yy += 0.1f;
}
{
yy -= 0.1f;
}
{
zz += 0.1f;
}
{
zz -= 0.1f;
}
glm::mat4 mPROJ = glm::ortho<float>(-10.0f, 10.0f, -10.0f, 10.0f, 0.05f, 50.f);
glm::mat4 lightView = glm::lookAt(glm::vec3(5.f, 5.f, 5.f), glm::vec3(0.0f, 0.0f, 0.0f), glm::vec3(0.0f, 1.0f, 0.0f));
glm::mat4 biasMatrix(
0.5, 0.0, 0.0, 0.0,
0.0, 0.5, 0.0, 0.0,
0.0, 0.0, 0.5, 0.0,
0.5, 0.5, 0.5, 1.0
);
glm::mat4 lightSpaceMatrix = biasMatrix * mPROJ * lightView;

glm::mat4 mModelToCamera;
glm::vec3 vPos = glm::vec3(xx, yy, zz);
mModelToCamera = glm::translate(glm::mat4(1.0), vPos);
mModelToCamera = glm::scale(mModelToCamera, glm::vec3(2.f));
glBindFramebuffer(GL_FRAMEBUFFER, depthMapFBO);
/*glEnable(GL_CULL_FACE);
glCullFace(GL_FRONT);*/
glClear(GL_DEPTH_BUFFER_BIT);

Environment::DrawCube(glm::vec3(xx, yy, zz), glm::vec3(2.f), glm::vec4(1.f), 7, true);

vPos = glm::vec3(xx + 3.f, yy, zz);
mModelToCamera = glm::translate(glm::mat4(1.0), vPos);
mModelToCamera = glm::scale(mModelToCamera, glm::vec3(2.f));
Environment::DrawCube(glm::vec3(xx + 3, yy, zz), glm::vec3(2.f), glm::vec4(1.f), 7, true);

RenderTargetManager->BackToNormalRenderer();
//glDisable(GL_CULL_FACE);
glClear(GL_COLOR_BUFFER_BIT | GL_DEPTH_BUFFER_BIT);

Renderer->MainProgram.Start();
Environment::DrawPlane(glm::vec3(0, 20.f, -20.f), glm::vec3(0.f, 90.f, 90.f), glm::vec3(10.f, 1.f, 10.f), depthMap);
Renderer->MainProgram.setUniform("EngineMatrices.DepthBiasMVP", lightSpaceMatrix);
glActiveTexture(GL_TEXTURE1);
glBindTexture(GL_TEXTURE_2D, depthMap);
glActiveTexture(GL_TEXTURE0);
Environment::DrawCube(glm::vec3(xx, yy, zz), glm::vec3(2.f), glm::vec4(1.f), 7, false);
Environment::DrawCube(glm::vec3(xx + 3.f, yy, zz), glm::vec3(2.f), glm::vec4(1.f), 7, false);

#ifdef ENGINE_EDITOR
#endif

//MODEL TYPE RENDERING
if (Renderer->IsCullFaceEnabled())
{
/*glEnable(GL_CULL_FACE);
glCullFace(GL_FRONT);
glFrontFace(GL_CW);*/
}

auto RenderEntity = [](Entity* _Entity)
{
if (_Entity->UpdateTransform())
{
_Entity->Mesh->Render();
}
if (_Entity->ShowCollider)
{
btVector3 one, two;
_Entity->Phys->RigidBody->getAabb(one, two);
Environment::DrawPoint(glm::vec3(one.x(), one.y(), one.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(one.x() + (two.x() - one.x()), one.y(), one.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(one.x(), one.y(), one.z() + (two.z() - one.z())), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(one.x(), one.y() + (two.y() - one.y()), one.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(two.x() - (two.x() - one.x()), two.y(), two.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(two.x(), two.y() - (two.y() - one.y()), two.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(two.x(), two.y(), two.z() - (two.z() - one.z())), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
Environment::DrawPoint(glm::vec3(two.x(), two.y(), two.z()), glm::vec3(2.f), glm::vec3(0.f, 1.f, 0.f));
}
};

//COL SHAPES
#ifdef ENGINE_EDITOR
for (uint i = 0; i < ColShapeManager->GetShapes(SHAPE_RECTANGLE); i++)
{
RectangleCol* currentShape = ColShapeManager->GetShape<RectangleCol>(SHAPE_RECTANGLE, i);
if (currentShape && currentShape->IsDebugEnabled())
currentShape->DebugShowCol();
}

for (uint i = 0; i < ColShapeManager->GetShapes(SHAPE_SPHERE); i++)
{
SphereCol* currentShape = ColShapeManager->GetShape<SphereCol>(SHAPE_SPHERE, i);
if (currentShape && currentShape->IsDebugEnabled())
currentShape->DebugShowCol();
}
#endif

//ENTITIES
std::map<float, Entity*> TransparentEntities;
std::map<float, Entity*> FarestEntities;

#ifdef ENGINE_EDITOR
EntityManager->ResetEntitiesRendered();
#endif

for (uint i = 0; i < EntityManager->GetEntities(); i++)
{
Entity* currentEntity = EntityManager->GetEntity(i);
float EntityToCamera = glm::distance(Camera->Position, currentEntity->Position);
if (currentEntity && currentEntity->CanRender() && EntityToCamera <= Renderer->GetRenderMaxDistance() && currentEntity->IsVisible())
{
if (currentEntity->IsDestroying())
{
float _alpha = currentEntity->GetAlpha();
if (_alpha <= 0.f)
{
EntityManager->DestroyEntity(currentEntity);
continue;
}
currentEntity->SetAlpha(_alpha - 0.01f);
}
#ifdef ENGINE_EDITOR
EntityManager->IncreaseEntitiesRendered();
#endif
if (currentEntity->GetAlpha() < 1.f)
TransparentEntities[EntityToCamera] = currentEntity;
else
FarestEntities[EntityToCamera] = currentEntity;
}
}

//RENDER TRANSPARENT ENTITIES & FAREST ENTITIES FIRST (lol?)

for (auto it = FarestEntities.begin(); it != FarestEntities.end(); ++it)
RenderEntity(it->second);

for (auto it = TransparentEntities.rbegin(); it != TransparentEntities.rend(); ++it)
RenderEntity(it->second);

TransparentEntities.empty();
TransparentEntities.clear();

//PARTICLE SYSTEM
for (uint i = 0; i < ParticleSystemManager::GetParticleSystems(); i++)
{
if (ParticleSystems[i] && ParticleSystems[i]->ID != INT_MAX)
{
ParticleSystems[i]->SetMatrices(&Renderer->GetProjectionMatrix(), Camera->Position, Camera->vView, Camera->vUp);
ParticleSystems[i]->UpdateParticles(0.025f);
ParticleSystems[i]->RenderParticles();
}
}

Renderer->ResetColor();
Renderer->MainProgram.Stop();

if (Renderer->IsCullFaceEnabled())
glDisable(GL_CULL_FACE);

OGLImGui::DrawGUI();

EventManager->CallEvent(ON_RENDER, EventArguments->GetEventArguments(ON_RENDER));

return true;
}


Sorry for the messed code but I use to do that when I'm testing something instead of organizing it first. Maybe I'm missing something stupid but I can't figure out lol. I appreciate any help. Thanks in advance.

Edited by Tonyx97

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show us the code of all shadowmapping shaders

i believe you are not clamping the projection. from light into the direction of light but its just a thought i don't even know if you are using directionla 'light' for that. everything that falls outside of light projection stays "not shadowed"

Edited by WiredCat

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Thanks for the reply WiredCat! It's directional light as you can see in the tutorial and also in my code where I transform the matrices using the projection matrix and the light direction matrix too. I've fixed the clamping and I know why it's repeated along the terrain because the terrain it's supposed to be a cube originally modelled with (1, 1, 1) scale and I scale it manually runtime to (100, 1, 100), I've tested with others big models and it doesn't repeat. The last problem is that I can't achieve properly the shadow for the entities that are casting the shadows. Take a look at this and this. You can see that it's not properly projected into the entities and I don't know what's happening. There is the shaders I to project:

MainFrag.frag:

#version 430
#extension GL_ARB_shader_storage_buffer_object : enable

smooth in vec2 texCoord;
smooth in vec3 vNormal;
smooth in vec3 vWorldPos;
smooth in vec4 vEyeSpacePos;
smooth in vec4 ShadowCoord;

uniform bool ison = false;

uniform vec4 vColor;
uniform vec4 vAmbientColor = vec4(1.0);
uniform vec3 vEyePosition;
uniform sampler2D gSampler;
uniform sampler2D gNormalMap;
uniform bool bUseOnlyColor = false;
uniform bool bSkybox = false;

uniform int bEnableBumpMap;
in mat3 vLightTangent;

#include "Directional_light.frag"
#include "Point_light.frag"
#include "Spot_light.frag"
#include "Fog.frag"
#include "Plasma.frag"
#include "Text_1.frag"
#include "Water.frag"
#include "RoomEditor.frag"

/*vec2 poissonDisk[16] = vec2[](
vec2( -0.94201624, -0.39906216 ),
vec2( 0.94558609, -0.76890725 ),
vec2( -0.094184101, -0.92938870 ),
vec2( 0.34495938, 0.29387760 ),
vec2( -0.91588581, 0.45771432 ),
vec2( -0.81544232, -0.87912464 ),
vec2( -0.38277543, 0.27676845 ),
vec2( 0.97484398, 0.75648379 ),
vec2( 0.44323325, -0.97511554 ),
vec2( 0.53742981, -0.47373420 ),
vec2( -0.26496911, -0.41893023 ),
vec2( 0.79197514, 0.19090188 ),
vec2( -0.24188840, 0.99706507 ),
vec2( -0.81409955, 0.91437590 ),
vec2( 0.19984126, 0.78641367 ),
vec2( 0.14383161, -0.14100790 )
);

float GetVisibility()
{
if (bShadowsOn == 0)
return 1.0;

float visibility = 1.0;
float bias = 0.000;

for (int i = 0; i < 4; i++)
{
int index = i;
vShadowSmooth = vShadowSmooth * 0.5 + 0.5;
visibility -= 0.25 * (1.0 - fSub);
}
return visibility;
}*/

{
vec3 projCoords = fragPosLightSpace.xyz / fragPosLightSpace.w;
projCoords = projCoords * 0.5 + 0.5;
float closestDepth = texture(shadowMap, projCoords.xy).r;
float currentDepth = projCoords.z;
float shadow = currentDepth > closestDepth ? 1.0 : 0.0;

if (projCoords.z > 1.0)
return 0.0;

return shadow * 0.6;
}

void main()
{
vec4 vTexColor = texture2D(gSampler, texCoord);
vec3 vFragColor;
vec3 vNormalized = normalize(vNormal);
if (!bUseOnlyColor)
gl_FragColor = vTexColor * vColor * vAmbientColor;				  //texture without any kind of effect applied (lights etc.)
else
gl_FragColor = vColor * vAmbientColor;							  //texture without any kind of effect applied (lights etc.)

vFragColor = gl_FragColor.xyz;

//ENGINE SHADERS, will change gl_FragColor if the entity has the shader enabled

//LIGHTING
if (iDirectionalLights > 0)
{
vec4 Diffuse_DirectionalLightsFinalColor = vec4(1.0);
vec4 Specular_DirectionalLightsFinalColor = vec4(1.0);
vec4 Normal_DirectionalLightsFinalColor = vec4(1.0);
for (int i = 0; i < iDirectionalLights; i++)
{
if (DirectionalLights.Lights[i].bEnabled == 1 && !bSkybox)
{
Diffuse_DirectionalLightsFinalColor += GetDirectionalLightColor(DirectionalLights.Lights[i], vNormalized);
Specular_DirectionalLightsFinalColor += GetDirectionalLightSpecularColor(vWorldPos, vEyePosition, DirectionalLights.Lights[i], vNormalized);

if (bEnableBumpMap == 1)
Normal_DirectionalLightsFinalColor += GetDirectionalLightNormalColor(DirectionalLights.Lights[i], vLightTangent, texCoord, gNormalMap);
}
}
gl_FragColor *= Diffuse_DirectionalLightsFinalColor * Specular_DirectionalLightsFinalColor * Normal_DirectionalLightsFinalColor;
}
if (iPointLights > 0)
{
vec4 Diffuse_PointLightsFinalColor = vec4(1.0);
vec4 Specular_PointLightsFinalColor = vec4(1.0);
for (int i = 0; i < iPointLights; i++)
{
if (PointLights.Lights[i].bEnabled == 1 && !bSkybox)
{
Diffuse_PointLightsFinalColor += GetPointLightColor(PointLights.Lights[i], vWorldPos, vNormalized);
Specular_PointLightsFinalColor += GetPointLightSpecularColor(vWorldPos, vEyePosition, PointLights.Lights[i], vNormalized);
}
}
gl_FragColor *= Diffuse_PointLightsFinalColor * Specular_PointLightsFinalColor;  // vec4(pow(vFragColor, vec3(1.0/2.2)), 1.0)

}
if (iSpotLights > 0)
{
vec4 SpotLightsFinalColor = vec4(1.0);
for (int i = 0; i < iSpotLights; i++)
{
if (SpotLights.Lights[i].bEnabled == 1)
{
SpotLightsFinalColor += GetSpotLightColor(SpotLights.Lights[i], vWorldPos);
}
}
gl_FragColor *= SpotLightsFinalColor;
}

if (bShadowsOn == 1)
{
//gl_FragColor *= GetVisibility();

gl_FragColor.w = 1.0;
}

if (FogData.Enabled)
gl_FragColor = mix(gl_FragColor, FogData.FogColor, GetFogFactor(abs(vEyeSpacePos.z / vEyeSpacePos.w)));
}



#version 330 core

layout(location = 0) in vec3 inPous;

uniform mat4 depthMVP;
uniform mat4 model;

void main()
{
gl_Position = depthMVP * model * vec4(inPous, 1.0);
}



#version 330 core

// Ouput data
layout(location = 0) out float fragmentdepth;

void main()
{
//fragmentdepth = gl_FragCoord.z;
}


These are all the shaders I use and everything related to shadows it's in the first code I sent in the main post so you can compare. I think I'm missing something in my C++ main code because as you can see in the picture the shadow is applied triangle by triangle and that should be something I'm missing not sure. Also in the commented code of the MainFrag you can see GetVisibility function which I tested and it works like the one I'm using but with smooth only, the shadow it's applied to the whole entity that casts the shadow and also happens the same error that there are parts in the entity that have no shadow in the borders...

Edited by Tonyx97

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mhm lets say i didint check the code.

first image shows that maybe you have depth precision problems, that means either bias it out by adding small number to the

tested fragment so actual_fragment_depth+0.0005 > shadow_depth_fragment then is in shadow might fix it.

but i define point light as something like. position, radius, color, direction, and i fit the frustum of the light as follows:

i define z far value for shadowmap, lets do not care for now for anything like torch lights etc. lets assume we have just directional light as sunlight. you define just light direction, color and z_far (the same one you define when you draw your shadowmap)

then

if fragment is in shadow frustum then

float actual_fragment_depth = distance(LightPOS, world_vertex_pos) / z_far;

after that

if (actual_fragment_depth > shadow_depth)
color = vec4(0.0, 0.0, 0.0, 1.0);
else
color = vec4(1.0, 1.0, 1.0, 0.0);

and second image

you need to add this code too you see there resolution precision problems, but theres an easy fix for that das dot product

if (dot( normalize( vectorAB(LightPOS, world_vertex_pos) ), VertexNormal) >= 0.0)
color = vec4(0.0, 0.0, 0.0, 1.0);


Did i forget to mention that you need to define vertice normals too, so each polygon has its own individual normal facing outwards the box center.

That should do, cheers/

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Thanks WiredCat! I've been the whole day working on this and struggling with the shaders and finally got it working taking into account your notes. My fear now is that maybe in the future when I use more complex models the bias I use will fuck up everything in shadows, I set the bias as 0.00005 which is pretty low but it's the one working for all models at the moment. Here's the result:

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well, i dont use any bias anyway :P butone thing i can tell you that bias is connected to z_near/z_far values  i cant remember exact connection between these.

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Staying in topic, after I finished directional light I started with spot light since they are easy because they don't need a cube map like point lights. I've been programming the shadows and FBO's for it but I encounter a curious problem projection the shadow, In this pic you can see that there are some black lines but the real shadow of the cube it's properly projected, I need a way to remove those lines somehow, maybe you WiredCat know about this issue.

The shadow calculation function:

float ShadowCalculation()
{
vec2 texelSize = 1.0 / textureSize(shadowMap, 0);
projCoords = projCoords * 0.5 + 0.5;
float closestDepth = texture(shadowMap, projCoords.xy).r;
float currentDepth = projCoords.z;
float shadow = 1.0;

for (int x = -1; x <= 4; x++)
for (int y = -1; y <= 4; y++)
shadow += currentDepth > (texture(shadowMap, projCoords.xy + vec2(x, y) * texelSize).r) ? 1.0 : 0.0;

shadow = currentDepth > closestDepth ? shadow : 0.0;

if (dot(normalize(vWorldPos - LightPos), normalize(vNormal)) >= 0.0)
{
return 0.0;
}

if (projCoords.z <= 0.0 || projCoords.z >= 1.0 || projCoords.x >= 1.0 || projCoords.y >= 1.0 || projCoords.x <= 0.0 || projCoords.y <= 0.0)
return 0.0;

return shadow * 0.8;
}


if (projCoords.z <= 0.0 || projCoords.z >= 1.0 || projCoords.x >= 1.0 || projCoords.y >= 1.0 || projCoords.x <= 0.0 || projCoords.y <= 0.0)


to remove the shadow outside of the perpective projection by the spot light. And where I call it:

if (bShadowsOn == 1)
{
FinalColor *= vec4(vec3(length(cross(normalize(vWorldPos - LightPos), vNormal))), 1.0);
else
FinalColor *= vec4(vec3(ShadowFactor), 1.0);
}


I also added the line when BackFaceShadow it's true to make progressive color changing to avoid faces change directly from shadow to light.

Edited by Tonyx97

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Looks like traditional shadow acne, to me?

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You're right I added some bias to remove the acne and now it works, do you know any article or website to fix the peter-panning without having to render the front faces? I'm modelling something and it doesn't have front faces due to remove useless geometry, the model is this and from this is from other perspective. At the moment I have no idea if this is possible to achieve but many games do that, for example GTA5 has a terrain with no front faces and the shadows of the hills are perfect, maybe this is more complex but I want to at least try or read how it's achieved.

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I solved the Peter Panning by virtually translating the world space position along its normal, instead of applying a depth bias

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LifeArtist
• By QQemka
Hello. I am coding a small thingy in my spare time. All i want to achieve is to load a heightmap (as the lowest possible walking terrain), some static meshes (elements of the environment) and a dynamic character (meaning i can move, collide with heightmap/static meshes and hold a varying item in a hand ). Got a bunch of questions, or rather problems i can't find solution to myself. Nearly all are deal with graphics/gpu, not the coding part. My c++ is on high enough level.
Let's go:
Heightmap - i obviously want it to be textured, size is hardcoded to 256x256 squares. I can't have one huge texture stretched over entire terrain cause every pixel would be enormous. Thats why i decided to use 2 specified textures. First will be a tileset consisting of 16 square tiles (u v range from 0 to 0.25 for first tile and so on) and second a 256x256 buffer with 0-15 value representing index of the tile from tileset for every heigtmap square. Problem is, how do i blend the edges nicely and make some computationally cheap changes so its not obvious there are only 16 tiles? Is it possible to generate such terrain with some existing program?
Collisions - i want to use bounding sphere and aabb. But should i store them for a model or entity instance? Meaning i have 20 same trees spawned using the same tree model, but every entity got its own transformation (position, scale etc). Storing collision component per instance grats faster access + is precalculated and transformed (takes additional memory, but who cares?), so i stick with this, right? What should i do if object is dynamically rotated? The aabb is no longer aligned and calculating per vertex min/max everytime object rotates/scales is pretty expensive, right?
Drawing aabb - problem similar to above (storing aabb data per instance or model). This time in my opinion per model is enough since every instance also does not have own vertex buffer but uses the shared one (so 20 trees share reference to one tree model). So rendering aabb is about taking the model's aabb, transforming with instance matrix and voila. What about aabb vertex buffer (this is more of a cosmetic question, just curious, bumped onto it in time of writing this). Is it better to make it as 8 points and index buffer (12 lines), or only 2 vertices with min/max x/y/z and having the shaders dynamically generate 6 other vertices and draw the box? Or maybe there should be just ONE 1x1x1 cube box template moved/scaled per entity?
What if one model got a diffuse texture and a normal map, and other has only diffuse? Should i pass some bool flag to shader with that info, or just assume that my game supports only diffuse maps without fancy stuff?
There were several more but i forgot/solved them at time of writing
• By RenanRR
Hi All,
I'm reading the tutorials from learnOpengl site (nice site) and I'm having a question on the camera (https://learnopengl.com/Getting-started/Camera).
I always saw the camera being manipulated with the lookat, but in tutorial I saw the camera being changed through the MVP arrays, which do not seem to be camera, but rather the scene that changes:
#version 330 core layout (location = 0) in vec3 aPos; layout (location = 1) in vec2 aTexCoord; out vec2 TexCoord; uniform mat4 model; uniform mat4 view; uniform mat4 projection; void main() { gl_Position = projection * view * model * vec4(aPos, 1.0f); TexCoord = vec2(aTexCoord.x, aTexCoord.y); } then, the matrix manipulated:
..... glm::mat4 projection = glm::perspective(glm::radians(fov), (float)SCR_WIDTH / (float)SCR_HEIGHT, 0.1f, 100.0f); ourShader.setMat4("projection", projection); .... glm::mat4 view = glm::lookAt(cameraPos, cameraPos + cameraFront, cameraUp); ourShader.setMat4("view", view); .... model = glm::rotate(model, glm::radians(angle), glm::vec3(1.0f, 0.3f, 0.5f)); ourShader.setMat4("model", model);
So, some doubts:
- Why use it like that?
- Is it okay to manipulate the camera that way?
-in this way, are not the vertex's positions that changes instead of the camera?
- I need to pass MVP to all shaders of object in my scenes ?

What it seems, is that the camera stands still and the scenery that changes...
it's right?

Thank you

• Sampling a floating point texture where the alpha channel holds 4-bytes of packed data into the float. I don't know how to cast the raw memory to treat it as an integer so I can perform bit-shifting operations.

int rgbValue = int(textureSample.w);//4 bytes of data packed as color
// algorithm might not be correct and endianness might need switching.
vec3 extractedData = vec3(  rgbValue & 0xFF000000,  (rgbValue << 8) & 0xFF000000, (rgbValue << 16) & 0xFF000000);
extractedData /= 255.0f;

• While writing a simple renderer using OpenGL, I faced an issue with the glGetUniformLocation function. For some reason, the location is coming to be -1.
Anyone has any idea .. what should I do?