diff options
Diffstat (limited to 'gl.c')
| -rw-r--r-- | gl.c | 257 |
1 files changed, 257 insertions, 0 deletions
@@ -0,0 +1,257 @@ +#include "lib/glcorearb.h" + +// macro trickery to avoid having to write everything twice +#define gl_for_each_proc(do)\ + do(DRAWARRAYS, DrawArrays)\ + do(GENTEXTURES, GenTextures)\ + do(DELETETEXTURES, DeleteTextures)\ + do(TEXIMAGE2D, TexImage2D)\ + do(BINDTEXTURE, BindTexture)\ + do(TEXPARAMETERI, TexParameteri)\ + do(GETERROR, GetError)\ + do(GETINTEGERV, GetIntegerv)\ + do(ENABLE, Enable)\ + do(DISABLE, Disable)\ + do(BLENDFUNC, BlendFunc)\ + do(VIEWPORT, Viewport)\ + do(CLEARCOLOR, ClearColor)\ + do(CLEAR, Clear)\ + do(FINISH, Finish)\ + do(CREATESHADER, CreateShader)\ + do(DELETESHADER, DeleteShader)\ + do(CREATEPROGRAM, CreateProgram)\ + do(SHADERSOURCE, ShaderSource)\ + do(GETSHADERIV, GetShaderiv)\ + do(GETSHADERINFOLOG, GetShaderInfoLog)\ + do(COMPILESHADER, CompileShader)\ + do(CREATEPROGRAM, CreateProgram)\ + do(DELETEPROGRAM, DeleteProgram)\ + do(ATTACHSHADER, AttachShader)\ + do(LINKPROGRAM, LinkProgram)\ + do(GETPROGRAMIV, GetProgramiv)\ + do(GETPROGRAMINFOLOG, GetProgramInfoLog)\ + do(USEPROGRAM, UseProgram)\ + do(GETATTRIBLOCATION, GetAttribLocation)\ + do(GETUNIFORMLOCATION, GetUniformLocation)\ + do(GENBUFFERS, GenBuffers)\ + do(DELETEBUFFERS, DeleteBuffers)\ + do(BINDBUFFER, BindBuffer)\ + do(BUFFERDATA, BufferData)\ + do(VERTEXATTRIBPOINTER, VertexAttribPointer)\ + do(ENABLEVERTEXATTRIBARRAY, EnableVertexAttribArray)\ + do(DISABLEVERTEXATTRIBARRAY, DisableVertexAttribArray)\ + do(GENVERTEXARRAYS, GenVertexArrays)\ + do(DELETEVERTEXARRAYS, DeleteVertexArrays)\ + do(BINDVERTEXARRAY, BindVertexArray)\ + do(ACTIVETEXTURE, ActiveTexture)\ + do(UNIFORM1F, Uniform1f)\ + do(UNIFORM2F, Uniform2f)\ + do(UNIFORM3F, Uniform3f)\ + do(UNIFORM4F, Uniform4f)\ + do(UNIFORM1I, Uniform1i)\ + do(UNIFORM2I, Uniform2i)\ + do(UNIFORM3I, Uniform3i)\ + do(UNIFORM4I, Uniform4i)\ + do(UNIFORM1D, Uniform1d)\ + do(UNIFORM2D, Uniform2d)\ + do(UNIFORM3D, Uniform3d)\ + do(UNIFORM4D, Uniform4d)\ + do(UNIFORMMATRIX4FV, UniformMatrix4fv)\ + do(DEBUGMESSAGECALLBACK, DebugMessageCallback)\ + do(DEBUGMESSAGECONTROL, DebugMessageControl)\ + +#define gl_declare_proc(upper, lower) static PFNGL##upper##PROC gl##lower; +gl_for_each_proc(gl_declare_proc) +#undef gl_declare_proc + +// set by main() +static int gl_version_major; +static int gl_version_minor; + +static void gl_get_procs(void) { + #define gl_get_proc(upper, lower) gl##lower = (PFNGL##upper##PROC)SDL_GL_GetProcAddress("gl" #lower); + gl_for_each_proc(gl_get_proc) + #undef gl_get_proc +} + +// compile a GLSL shader +static GLuint gl_compile_shader(char const *code, GLenum shader_type) { + GLuint shader = glCreateShader(shader_type); + glShaderSource(shader, 1, &code, NULL); + glCompileShader(shader); + GLint status = 0; + glGetShaderiv(shader, GL_COMPILE_STATUS, &status); + if (status == GL_FALSE) { + char log[1024] = {0}; + glGetShaderInfoLog(shader, sizeof log - 1, NULL, log); + debug_println("Error compiling shader: %s", log); + return 0; + } + return shader; +} + +// link together GL shaders +static GLuint gl_link_program(GLuint *shaders, size_t count) { + GLuint program = glCreateProgram(); + if (program) { + for (size_t i = 0; i < count; ++i) { + if (!shaders[i]) { + glDeleteProgram(program); + return 0; + } + glAttachShader(program, shaders[i]); + } + glLinkProgram(program); + GLint status = 0; + glGetProgramiv(program, GL_LINK_STATUS, &status); + if (status == GL_FALSE) { + char log[1024] = {0}; + glGetProgramInfoLog(program, sizeof log - 1, NULL, log); + debug_println("Error linking shaders: %s", log); + glDeleteProgram(program); + return 0; + } + } + return program; +} + +static GLuint gl_compile_and_link_shaders(char const *vshader_code, char const *fshader_code) { + GLuint shaders[2]; + shaders[0] = gl_compile_shader(vshader_code, GL_VERTEX_SHADER); + shaders[1] = gl_compile_shader(fshader_code, GL_FRAGMENT_SHADER); + GLuint program = gl_link_program(shaders, 2); + if (shaders[0]) glDeleteShader(shaders[0]); + if (shaders[1]) glDeleteShader(shaders[1]); + if (program) { + debug_print("Successfully linked program %u.\n", program); + } + return program; +} + +static GLuint gl_attrib_loc(GLuint program, char const *attrib) { + GLint loc = glGetAttribLocation(program, attrib); + if (loc == -1) { + debug_print("Couldn't find vertex attribute %s.\n", attrib); + return (GLuint)-1; + } + return (GLuint)loc; +} + +static GLint gl_uniform_loc(GLuint program, char const *uniform) { + GLint loc = glGetUniformLocation(program, uniform); + if (loc == -1) { + debug_print("Couldn't find uniform: %s.\n", uniform); + return -1; + } + return loc; +} + +typedef struct { + v2 pos; + v4 color; +} GLSimpleVertex; +typedef struct { + GLSimpleVertex v1, v2, v3; +} GLSimpleTriangle; + +static GLSimpleTriangle *gl_geometry_triangles; +static GLuint gl_geometry_program; +static GLuint gl_geometry_v_pos; +static GLuint gl_geometry_v_color; +static GLuint gl_geometry_vbo, gl_geometry_vao; + +static void gl_geometry_init(void) { + char const *vshader_code = "#version 110\n\ + attribute vec2 v_pos;\n\ + attribute vec4 v_color;\n\ + varying vec4 color;\n\ + void main() {\n\ + gl_Position = vec4(v_pos, 0.0, 1.0);\n\ + color = v_color;\n\ + }\n\ + "; + char const *fshader_code = "#version 110\n\ + varying vec4 color;\n\ + void main() {\n\ + gl_FragColor = color;\n\ + }\n\ + "; + + gl_geometry_program = gl_compile_and_link_shaders(vshader_code, fshader_code); + gl_geometry_v_pos = gl_attrib_loc(gl_geometry_program, "v_pos"); + gl_geometry_v_color = gl_attrib_loc(gl_geometry_program, "v_color"); + + glGenBuffers(1, &gl_geometry_vbo); + if (gl_version_major >= 3) + glGenVertexArrays(1, &gl_geometry_vao); +} + +static float gl_window_width, gl_window_height; + +static void gl_convert_to_ndc(v2 *pos) { + pos->x = pos->x / gl_window_width * 2.0f - 1.0f; + pos->y = 1.0f - pos->y / gl_window_height * 2.0f; +} + +static void gl_geometry_rect(Rect r, u32 color_rgba) { + v4 color = rgba_u32_to_v4(color_rgba); + + v2 p1 = r.pos; + v2 p2 = v2_add(r.pos, V2(0, r.size.y)); + v2 p3 = v2_add(r.pos, V2(r.size.x, r.size.y)); + v2 p4 = v2_add(r.pos, V2(r.size.x, 0)); + + GLSimpleTriangle triangle = { + {p1, color}, + {p2, color}, + {p3, color} + }; + arr_add(gl_geometry_triangles, triangle); + triangle.v1.pos = p3; + triangle.v2.pos = p4; + triangle.v3.pos = p1; + arr_add(gl_geometry_triangles, triangle); +} + +static void gl_geometry_rect_border(Rect r, float border_thickness, u32 color) { + float border_radius = border_thickness * 0.5f; + float x1 = r.pos.x, y1 = r.pos.y, x2 = x1 + r.size.x, y2 = y1 + r.size.y; + + // make sure rectangle isn't too small + x2 = maxf(x2, x1 + 2 * border_radius); + y2 = maxf(y2, y1 + 2 * border_radius); + + gl_geometry_rect(rect4(x1+border_radius, y1-border_radius, x2+border_radius, y1+border_radius), color); + gl_geometry_rect(rect4(x1-border_radius, y2-border_radius, x2-border_radius, y2+border_radius), color); + gl_geometry_rect(rect4(x1-border_radius, y1-border_radius, x1+border_radius, y2-border_radius), color); + gl_geometry_rect(rect4(x2-border_radius, y1+border_radius, x2+border_radius, y2+border_radius), color); +} + +static void gl_geometry_draw(void) { + size_t ntriangles = arr_len(gl_geometry_triangles); + + if (ntriangles == 0) return; + + // convert coordinates to NDC + for (size_t i = 0; i < ntriangles; ++i) { + GLSimpleTriangle *triangle = &gl_geometry_triangles[i]; + gl_convert_to_ndc(&triangle->v1.pos); + gl_convert_to_ndc(&triangle->v2.pos); + gl_convert_to_ndc(&triangle->v3.pos); + } + + if (gl_version_major >= 3) + glBindVertexArray(gl_geometry_vao); + + glBindBuffer(GL_ARRAY_BUFFER, gl_geometry_vbo); + glBufferData(GL_ARRAY_BUFFER, (GLsizeiptr)(ntriangles * sizeof(GLSimpleTriangle)), gl_geometry_triangles, GL_STREAM_DRAW); + glVertexAttribPointer(gl_geometry_v_pos, 2, GL_FLOAT, 0, sizeof(GLSimpleVertex), (void *)offsetof(GLSimpleVertex, pos)); + glEnableVertexAttribArray(gl_geometry_v_pos); + glVertexAttribPointer(gl_geometry_v_color, 4, GL_FLOAT, 0, sizeof(GLSimpleVertex), (void *)offsetof(GLSimpleVertex, color)); + glEnableVertexAttribArray(gl_geometry_v_color); + + glUseProgram(gl_geometry_program); + glDrawArrays(GL_TRIANGLES, 0, (GLsizei)(3 * ntriangles)); + + arr_clear(gl_geometry_triangles); +} |