I'm using modern OpenGL 4.3 core.
I just realized that 1024p x 1024p tileset is too small for my needs. So, I replaced it with 1024p x 1024p x 4p 3D texture. (I know, it's not the best solution, and I better to use 2D texture array. I'm just wondering why my current solution doesn't work.)
x and y texture coordinates work fine, same as before. z also work, but a bit incorrectly. I would expect the 1st layer to have z == 0.0, 2nd layer - z == 0.3333333, 3rd layer - z == 0.66666666 and 4rd one - z == 1.0.
The 1st and 4th layers work as expected. But 0.33333333 and 0.66666666 give me incorrect results:
0.33333333 -> 1st layer mixed with 2nd layer
0.66666666 -> 3rd layer mixed with 4th layer
(I'm using linear filtering, that's why they mix together.)
I tried to pick the right z values for 2nd and 3rd layers:
2nd displays fine when z == 0.38
3rd displays fine when z == 0.62
(These numbers are approximate, of course.)
Any ideas why this happen and how I can fix this?
This is how I create the texture:
glActiveTexture(GL_TEXTURE1);
glGenTextures(1, &maintex);
glBindTexture(GL_TEXTURE_3D, maintex);
glTexImage3D(GL_TEXTURE_3D, 0, GL_RGBA8, TEXSIZE, TEXSIZE, 4, 0, GL_RGBA, GL_UNSIGNED_BYTE, textemp);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MIN_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_MAG_FILTER, GL_LINEAR);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_S, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_T, GL_CLAMP_TO_EDGE);
glTexParameteri(GL_TEXTURE_3D, GL_TEXTURE_WRAP_R, GL_CLAMP_TO_EDGE);
And it's my shader:
const char *vertex = 1+R"(
#version 430
uniform layout(location = 3) vec2 fac;
in layout(location = 0) vec2 vpos; // vertex coords
in layout(location = 1) vec3 tpos; // texture coords
in layout(location = 2) vec4 c_off; // color offset = vec4(0,0,0,0) by default
in layout(location = 3) vec4 c_mult; // color multiplicator = vec4(1,1,1,1) by default
// These two are used to do some sort of gamma correction
out vec3 var_tpos;
out vec4 var_c_off;
out vec4 var_c_mult;
void main()
{
var_tpos = tpos;
var_c_off = c_off;
var_c_mult = c_mult;
gl_Position = vec4(vpos.x * fac.x - 1, vpos.y * fac.y + 1, 0, 1);
})";
const char *fragment = 1+R"(
#version 430
uniform layout(location = 0) sampler3D tex;
in vec3 var_tpos;
in vec4 var_c_off;
in vec4 var_c_mult;
out vec4 color;
void main()
{
color = texture(tex, vec3(var_tpos.x / 1024, var_tpos.y / 1024, var_tpos.z));
color.x *= var_c_mult.x;
color.y *= var_c_mult.y;
color.z *= var_c_mult.z;
color.w *= var_c_mult.w;
color += var_c_off;
})";
