I have a shader I'm attempting to use and I've come across an issue that i can't solve since my knowledge of glsl is limited. I'm using a texture as a mask and to debug this issue I simply use this textures pixel color as the gl_FragColor, I'll post some images to show what it looks like and what it should look like.
Image link; https://imgur.com/EBt2vbL
It seems related to the coordinates from gl_TexCoord[0].xy not getting the proper coordinates of the dissolve texture
main.cpp
#include "Engine.h"
#include <stdio.h>
#include <iostream>
#include <windows.h>
int main(int argc, char *argv[])
{
try
{
Engine game;
game.Run();
}
catch (std::exception& err)
{
std::cout << "\nException: " << err.what() << std::endl;
}
return 0;
}
Engine.h
#pragma once
#include <SFML/System.hpp>
#include <SFML/Graphics.hpp>
#include <SFML/Window.hpp>
#include <SFML/Audio.hpp>
#include <SFML/Network.hpp>
#include <vector>
#include <iostream>
class Engine
{
public:
Engine();
void Run();
void HandleEvents(sf::Time deltaTime);
void Update(sf::Time deltaTime);
void BuildVertices();
void Draw();
private:
bool running;
bool hasFocus;
bool fullScreen;
sf::RenderWindow mainWindow;
sf::Time deltaTime;
sf::Event event;
sf::Vector2i screenResolution;
sf::Vector2i mousePosition;
sf::VertexArray vertices;
sf::Vertex vertex;
sf::Shader dissolveShader;
sf::Texture dissolveTexture;
sf::RenderStates renderState;
float dissolveValue;
sf::Texture objectSpriteSheetTexture;
};
Engine.cpp
#include "Engine.h"
static const sf::Time TimePerFrame = sf::seconds(1.f / 60.f);
Engine::Engine()
: hasFocus(true)
, fullScreen(fullScreen)
, running(false)
, dissolveValue(1.0f)
, vertices(sf::Quads)
{
mainWindow.create(sf::VideoMode(640, 480), "Test", sf::Style::Titlebar);
mainWindow.setPosition(sf::Vector2i(0, 0));
screenResolution.x = 640;
screenResolution.y = 480;
// 512x512 sheet, each sprite is 128x128
if (!objectSpriteSheetTexture.loadFromFile("ObjectSheet.png"))
std::cout << "failed to load ObjectSheet.png" << std::endl;
if (!dissolveTexture.loadFromFile("DissolveTexture.png"))
std::cout << "failed to load DissolveTexture.png" << std::endl;
if (!dissolveShader.loadFromFile("DissolveShader.frag", sf::Shader::Fragment))
{
std::cout << "failed to load DissolveShader.frag" << std::endl;
}
dissolveShader.setUniform("sourceTexture", sf::Shader::CurrentTexture);
dissolveShader.setUniform("dissolveTexture", dissolveTexture);
renderState.shader = &dissolveShader;
renderState.texture = &objectSpriteSheetTexture;
}
void Engine::Run()
{
// main loop
sf::Clock clock;
sf::Time timeSinceLastUpdate = sf::Time::Zero;
sf::Time elapsedTime;
running = true;
while(running)
{
elapsedTime = clock.restart();
timeSinceLastUpdate += elapsedTime;
HandleEvents(TimePerFrame);
while(timeSinceLastUpdate > TimePerFrame)
{
timeSinceLastUpdate -= TimePerFrame;
Update(TimePerFrame);
}
BuildVertices();
Draw();
}
}
void Engine::HandleEvents(sf::Time deltaTime)
{
mousePosition = sf::Mouse::getPosition(mainWindow);
while(mainWindow.pollEvent(event))
{
if(event.type == sf::Event::Closed)
mainWindow.close();
if (event.type == sf::Event::KeyPressed)
{
if (event.key.code == sf::Keyboard::Escape)
{
running = false;
}
}
}
}
void Engine::Update(sf::Time deltaTime)
{
}
void Engine::BuildVertices()
{
vertices.clear();
int frameSize = 128;
sf::Vector2i objectPosition(100, 100);
sf::Vector2i spriteSheetTextureCoordinates(0, 128);
vertex.position.x = objectPosition.x;
vertex.position.y = objectPosition.y;
vertex.texCoords.x = spriteSheetTextureCoordinates.x;
vertex.texCoords.y = spriteSheetTextureCoordinates.y;
vertices.append(vertex);
vertex.position.x = objectPosition.x + frameSize;
vertex.position.y = objectPosition.y;
vertex.texCoords.x = spriteSheetTextureCoordinates.x + frameSize;
vertex.texCoords.y = spriteSheetTextureCoordinates.y;
vertices.append(vertex);
vertex.position.x = objectPosition.x + frameSize;
vertex.position.y = objectPosition.y + frameSize;
vertex.texCoords.x = spriteSheetTextureCoordinates.x + frameSize;
vertex.texCoords.y = spriteSheetTextureCoordinates.y + frameSize;
vertices.append(vertex);
vertex.position.x = objectPosition.x;
vertex.position.y = objectPosition.y + frameSize;
vertex.texCoords.x = spriteSheetTextureCoordinates.x;
vertex.texCoords.y = spriteSheetTextureCoordinates.y + frameSize;
vertices.append(vertex);
}
void Engine::Draw()
{
mainWindow.clear(sf::Color::Black);
dissolveShader.setUniform("dissolveValue", dissolveValue);
mainWindow.draw(vertices, renderState);
mainWindow.display();
}
the vertex shader is a standard pass through handled by sfml.
the fragment shader;
#version 130
// used as the mask to determine if a pixel of the source texture should be drawn, 128x128
uniform sampler2D dissolveTexture;
// the texture of the object i'm drawing, a 128x128 part of a 512x512 sprite sheet
uniform sampler2D sourceTexture;
// set to 1.0 for debug
uniform float dissolveValue;
void main( void )
{
vec4 sourceColor = texture2D(sourceTexture, gl_TexCoord[0].xy);
vec4 maskColor = texture2D(dissolveTexture, gl_TexCoord[0].xy);
if(maskColor.r <= dissolveValue)
{
// it would return the source pixel color here one the issue is solved
// gl_FragColor = sourceColor;
// debuging, so returning the mask textures pixel color
gl_FragColor = maskColor;
}
else
{
gl_FragColor = sourceColor;
}
}
I'm probably overlooking something simple, so if someone can point me in the right direction i'd appreciate it, thanks!
