| 1 | module shader_mod |
| 2 | use, intrinsic :: iso_c_binding |
| 3 | use gl_bindings |
| 4 | implicit none |
| 5 | private |
| 6 | |
| 7 | public :: shader_t |
| 8 | public :: shader_create, shader_destroy, shader_use |
| 9 | public :: shader_set_projection, shader_set_int |
| 10 | |
| 11 | type :: shader_t |
| 12 | integer :: program_id = 0 |
| 13 | integer :: projection_loc = -1 |
| 14 | integer :: atlas_loc = -1 |
| 15 | logical :: valid = .false. |
| 16 | end type shader_t |
| 17 | |
| 18 | contains |
| 19 | |
| 20 | ! Create a shader program from vertex and fragment source |
| 21 | function shader_create(vert_source, frag_source) result(shader) |
| 22 | character(len=*), intent(in) :: vert_source, frag_source |
| 23 | type(shader_t) :: shader |
| 24 | integer :: vert_id, frag_id |
| 25 | integer :: success |
| 26 | character(len=512) :: log_buffer |
| 27 | |
| 28 | ! Compile vertex shader |
| 29 | vert_id = glCreateShader(GL_VERTEX_SHADER) |
| 30 | call glShaderSource(vert_id, vert_source // c_null_char) |
| 31 | call glCompileShader(vert_id) |
| 32 | |
| 33 | success = glGetShaderCompileStatus(vert_id) |
| 34 | if (success == 0) then |
| 35 | call glGetShaderInfoLog(vert_id, log_buffer, 512) |
| 36 | print *, "Error: Vertex shader compilation failed:" |
| 37 | print *, trim(log_buffer) |
| 38 | call glDeleteShader(vert_id) |
| 39 | return |
| 40 | end if |
| 41 | |
| 42 | ! Compile fragment shader |
| 43 | frag_id = glCreateShader(GL_FRAGMENT_SHADER) |
| 44 | call glShaderSource(frag_id, frag_source // c_null_char) |
| 45 | call glCompileShader(frag_id) |
| 46 | |
| 47 | success = glGetShaderCompileStatus(frag_id) |
| 48 | if (success == 0) then |
| 49 | call glGetShaderInfoLog(frag_id, log_buffer, 512) |
| 50 | print *, "Error: Fragment shader compilation failed:" |
| 51 | print *, trim(log_buffer) |
| 52 | call glDeleteShader(vert_id) |
| 53 | call glDeleteShader(frag_id) |
| 54 | return |
| 55 | end if |
| 56 | |
| 57 | ! Link program |
| 58 | shader%program_id = glCreateProgram() |
| 59 | call glAttachShader(shader%program_id, vert_id) |
| 60 | call glAttachShader(shader%program_id, frag_id) |
| 61 | call glLinkProgram(shader%program_id) |
| 62 | |
| 63 | success = glGetProgramLinkStatus(shader%program_id) |
| 64 | if (success == 0) then |
| 65 | call glGetProgramInfoLog(shader%program_id, log_buffer, 512) |
| 66 | print *, "Error: Shader program linking failed:" |
| 67 | print *, trim(log_buffer) |
| 68 | call glDeleteShader(vert_id) |
| 69 | call glDeleteShader(frag_id) |
| 70 | call glDeleteProgram(shader%program_id) |
| 71 | shader%program_id = 0 |
| 72 | return |
| 73 | end if |
| 74 | |
| 75 | ! Clean up shaders (they're linked into the program now) |
| 76 | call glDeleteShader(vert_id) |
| 77 | call glDeleteShader(frag_id) |
| 78 | |
| 79 | ! Get uniform locations |
| 80 | shader%projection_loc = glGetUniformLocation(shader%program_id, & |
| 81 | "u_projection" // c_null_char) |
| 82 | shader%atlas_loc = glGetUniformLocation(shader%program_id, & |
| 83 | "u_atlas" // c_null_char) |
| 84 | |
| 85 | shader%valid = .true. |
| 86 | |
| 87 | end function shader_create |
| 88 | |
| 89 | ! Use this shader program |
| 90 | subroutine shader_use(shader) |
| 91 | type(shader_t), intent(in) :: shader |
| 92 | if (shader%valid) then |
| 93 | call glUseProgram(shader%program_id) |
| 94 | end if |
| 95 | end subroutine shader_use |
| 96 | |
| 97 | ! Set the projection matrix uniform |
| 98 | subroutine shader_set_projection(shader, matrix) |
| 99 | type(shader_t), intent(in) :: shader |
| 100 | real(c_float), intent(in) :: matrix(4,4) |
| 101 | |
| 102 | if (shader%valid .and. shader%projection_loc >= 0) then |
| 103 | call glUniformMatrix4fv(shader%projection_loc, 1, GL_FALSE, matrix) |
| 104 | end if |
| 105 | end subroutine shader_set_projection |
| 106 | |
| 107 | ! Set an integer uniform |
| 108 | subroutine shader_set_int(shader, name, value) |
| 109 | type(shader_t), intent(in) :: shader |
| 110 | character(len=*), intent(in) :: name |
| 111 | integer, intent(in) :: value |
| 112 | integer :: loc |
| 113 | |
| 114 | if (shader%valid) then |
| 115 | loc = glGetUniformLocation(shader%program_id, name // c_null_char) |
| 116 | if (loc >= 0) then |
| 117 | call glUniform1i(loc, value) |
| 118 | end if |
| 119 | end if |
| 120 | end subroutine shader_set_int |
| 121 | |
| 122 | ! Destroy shader program |
| 123 | subroutine shader_destroy(shader) |
| 124 | type(shader_t), intent(inout) :: shader |
| 125 | |
| 126 | if (shader%program_id > 0) then |
| 127 | call glDeleteProgram(shader%program_id) |
| 128 | shader%program_id = 0 |
| 129 | end if |
| 130 | shader%valid = .false. |
| 131 | end subroutine shader_destroy |
| 132 | |
| 133 | end module shader_mod |
| 134 |