Screen messing up

Shaders
1

When I add a standard shader to the dark green mesh it messes up my screen. Without shader: https://db.tt/rBpYifpy With shader: https://db.tt/qFZSTQHf
Am I missing something obvious?

2

Looks to me like your shader is expecting a texture and not finding one.

3

Maybe…
self.mk is my mesh and
I tried:

    self.mk.shader = shader("Dropbox:BasicShader")
    self.mk.texture = readImage("Dropbox:Grass")
    self.mk.shader.texture = readImage("Dropbox:Grass")

I am just using a startup shader where I haven’t changed any code.

4

Can we see the rest of the code, including the shader?

5

@Holger_gott - your shader probably has an error. It’s possible that recent changes to Codea or OpenGL have broken it, but we can’t tell you unless we know which shader it is and how you’ve used it.

By the way, the correct way to set the texture is “self.mk.texture =”, not “self.mk.shader.texture=”.

6

Simplified code:


-- Problem

-- Use this function to perform your initial setup
function setup()
    v = {}
    t = {}
    table.insert(v,vec3(-200,0,-200))
    table.insert(v,vec3(200,0,-200))
    table.insert(v,vec3(-200,0,200))
    table.insert(v,vec3(200,0,200))
    table.insert(v,vec3(200,0,-200))
    table.insert(v,vec3(-200,0,200))
    table.insert(t,vec2(0,0))
    table.insert(t,vec2(1,0))
    table.insert(t,vec2(0,1))
    table.insert(t,vec2(1,1))
    table.insert(t,vec2(1,0))
    table.insert(t,vec2(0,1))
    mk = mesh()
    
    mk.vertices = v
    mk.texCoords= t
    mk.texture = readImage("Planet Cute:Gem Blue")
    
    --mk.shader=shader("Dropbox:BasicShader")
    
    pos=vec3(0,200,700)
end

function draw()
    background(40, 40, 50)
    perspective()
    camera(pos.x,pos.y,pos.z,0,0,-2000)
    mk:draw()
    resetMatrix()
    ortho()
    viewMatrix(matrix())
    sprite("Cargo Bot:Clear Button",100,100)
    strokeWidth(32)
    stroke(255, 0, 0, 255)
    lineCapMode(ROUND)
    line(WIDTH-30,30,WIDTH-30,80)
    text("problem",60,HEIGHT-40)
end
7

The shader:

//
// A basic vertex shader
//

//This is the current model * view * projection matrix
// Codea sets it automatically
uniform mat4 modelViewProjection;

//This is the current mesh vertex position, color and tex coord
// Set automatically
attribute vec4 position;
attribute vec4 color;
attribute vec2 texCoord;

//This is an output variable that will be passed to the fragment shader
varying lowp vec4 vColor;
varying highp vec2 vTexCoord;

void main()
{
    //Pass the mesh color to the fragment shader
    vColor = color;
    vTexCoord = texCoord;
    
    //Multiply the vertex position by our combined transform
    gl_Position = modelViewProjection * position;
}

//
// A basic fragment shader
//

//Default precision qualifier
precision highp float;

//This represents the current texture on the mesh
uniform lowp sampler2D texture;

//The interpolated vertex color for this fragment
varying lowp vec4 vColor;

//The interpolated texture coordinate for this fragment
varying highp vec2 vTexCoord;

void main()
{
    //Sample the texture at the interpolated coordinate
    lowp vec4 col = texture2D( texture, vTexCoord ) * vColor;

    //Set the output color to the texture color
    gl_FragColor = col;
}
8

@Holger_gott - You need to add this line after mk.texCoords=t

mk:setColors(color(255))

The reason it matters is that the standard fragment shader multiplies the texture colour by the vertex colour, and if you haven’t set it, it gives an error or uses black (the result is the same). Setting it to white (which the shader treats as 1 rather than 255) will draw the mesh properly.

You can alternatively fix it by removing * vColor from the fragment shader

PS if you are interested in exploring shaders, I have an ebook here

9

It fixes the mesh but the text, the line and the sprite are still not drawn correct

10

oh yes they are, for me, anyway