Я пытаюсь получить так называемые координаты мирового пространства для 2D-рендеринга, создавая матрицу ортогональной проекции.Но результат разочаровывает, я ожидаю синий треугольник, но в правом нижнем углу есть только несколько синих пикселей.
Вот мой код на языке Nim,Это очень упрощенная версия, которая воспроизводит проблему.
Важная часть находится в функции "projection2D" или, возможно, в вершинном шейдере.Я не думаю, что проблема в другом, но для безопасности я выложу полный пример
type
OGLfloat = float32
OGLuint = uint32
OGLint = int32
type Mat4x4* = array[16, OGLfloat] # 4 x 4 Matrix
# Here OpenGL constants should be here but not pasted to save space.
#....
const
POSITION_LENGTH = 3.OGLint
COLOR_LENGTH = 4.OGLint
const
WINDOW_W = 640
WINDOW_H = 480
let
colorDataOffset = POSITION_LENGTH * OGLint(sizeof(OGLfloat))
# OpenGL function import should be here.
#...
var
# Thanks to an orthogonal projection matrix I expect to use coordinates in pixels.
vertices = @[OGLfloat(420), 0, 0, # Position
0, 0, 1, 1, # Color
640, 480, 0,
0, 0, 1, 1,
0, 480, 0,
0, 0, 1, 1]
indices = @[OGLuint(0), 1 , 2]
proc projection2D(left, right, bottom, top, far, near:float):Mat4x4 =
result = [OGLfloat(1), 0, 0, 0, # Start from an identity matrix.
0, 1, 0, 0,
0, 0, 1, 0,
0, 0, 0, 1]
# Orthographic projection, inspired from a Wikipedia article example.
result[0] = OGLfloat(2.0 / (right - left))
result[5] = OGLfloat(2.0 / (top - bottom))
result[3] = OGLfloat(- ((right + left) / (right - left)))
result[7] = OGLfloat(- ((top + bottom) / (top - bottom)))
result[10] = OGLfloat(-2 / (far - near))
result[11] = OGLfloat(-((far + near)/(far - near)))
# These parameters comes from "learnopengl.com".
var projectionMatrix = projection2D(0.0, OGLfloat(WINDOW_W), OGLfloat(WINDOW_H), 0.0, - 1.0, 1.0)
var glfwErr = glfwInit()
glfwWindowHint(GLFW_CONTEXT_VERSION_MAJOR, 3)
glfwWindowHint(GLFW_CONTEXT_VERSION_MINOR, 3)
glfwWindowHint(GLFW_OPENGL_PROFILE, GLFW_OPENGL_CORE_PROFILE)
var winHandle = glfwCreateWindow(WINDOW_W, WINDOW_H)
glfwMakeContextCurrent(winHandle)
var glewErr = glewInit()
var
shadID:OGLuint
vertSrc:cstring = """
#version 330 core
layout (location = 0) in vec3 aPos;
layout (location = 1) in vec4 aColor;
out vec4 vColor;
uniform mat4 projection;
void main()
{
gl_Position = projection * vec4(aPos, 1.0f);
vColor = aColor;
}
"""
fragSrc:cstring = """
#version 330 core
out vec4 FragColor;
in vec4 vColor;
void main()
{
FragColor = vColor;
}
"""
proc send_src(vert:var cstring, frag:var cstring):OGLuint =
var success:OGLint
# vertex
var vertexShader = glCreateShader(GL_VERTEX_SHADER)
glShaderSource(vertexShader, 1, addr vert, nil)
glCompileShader(vertexShader)
# Check compilation errors.
glGetShaderiv(vertexShader, GL_COMPILE_STATUS, addr success)
if bool(success) == false:
echo(" vertex shader compilation failed (send_src)")
else:
echo("vertexShader compiled (send_src)")
# fragment
var fragmentShader = glCreateShader(GL_FRAGMENT_SHADER)
glShaderSource(fragmentShader, 1, addr frag, nil)
glCompileShader(fragmentShader)
# Check compilation errors.
glGetShaderiv(fragmentShader, GL_COMPILE_STATUS, addr success)
if bool(success) == false:
echo("fragment shader compilation failed (send_src)")
else:
echo("fragmentShader compiled (send_src)")
# Shader program
result = glCreateProgram()
glAttachShader(result, vertexShader)
glAttachShader(result, fragmentShader)
glLinkProgram(result)
# Check for linkage errors.
glGetProgramiv(result, GL_LINK_STATUS, addr success)
if success == 0:
echo("program linking failed (send_src)")
else:
echo("shader linked (send_src)")
glDeleteShader(vertexShader)
glDeleteShader(fragmentShader)
glViewport(0, 0, WINDOW_W, WINDOW_H)
shadID = send_src(vertSrc, fragSrc)
var VAO, VBO, EBO:OGLuint
glGenVertexArrays(1, addr VAO)
glGenBuffers(1, addr VBO)
glGenBuffers(1, addr EBO)
glBindVertexArray(VAO)
glBindBuffer(GL_ARRAY_BUFFER, VBO)
glBufferData(GL_ARRAY_BUFFER, vertices.len * sizeof(OGLfloat),
addr vertices[0], GL_STATIC_DRAW)
glBindBuffer(GL_ELEMENT_ARRAY_BUFFER, EBO)
glBufferData(GL_ELEMENT_ARRAY_BUFFER, indices.len * sizeof(OGLuint),
addr indices[0], GL_STATIC_DRAW)
# Position layout
glVertexAttribPointer(0, POSITION_LENGTH, GL_FLOAT, GL_FALSE, (POSITION_LENGTH + COLOR_LENGTH) * OGLint(sizeof(OGLfloat)),
nil)
glEnableVertexAttribArray(0)
# Color layout
glVertexAttribPointer(1, COLOR_LENGTH, GL_FLOAT, GL_FALSE, (POSITION_LENGTH + COLOR_LENGTH) * OGLint(sizeof(OGLfloat)),
cast[pointer](colorDataOffset))
glEnableVertexAttribArray(1)
glBindBuffer(GL_ARRAY_BUFFER, 0)
glBindVertexArray(0)
glUseProgram(shadID)
while bool(glfwWindowShouldClose(winHandle)) == false:
glClearColor(0.2, 0.3, 0.3, 1.0)
glClear(GL_COLOR_BUFFER_BIT)
glBindVertexArray(VAO)
glUniformMatrix4fv(glGetUniformLocation(shadID, "projection"), 1, GL_FALSE, addr projectionMatrix[0])
glDrawElements(GL_TRIANGLES, OGLint(indices.len), GL_UNSIGNED_INT, nil)
glfwSwapBuffers(winHandle)
glfwPollEvents()
glDeleteVertexArrays(1, addr VAO)
glDeleteBuffers(1, addr VBO)
glDeleteBuffers(1, addr EBO)
glfwDestroyWindow(winHandle)
glfwTerminate()
Не стесняйтесь поделиться своими мыслями!