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Support rendering part of a mesh

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This commit is contained in:
Nikita Lisitsa 2020-10-02 19:18:35 +03:00
parent 3c215d6abb
commit 23de4a520e
1 changed files with 42 additions and 7 deletions
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49
libs/gfx/include/psemek/gfx/mesh.hpp
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@ -8,6 +8,8 @@
#include <psemek/geom/simplex.hpp> #include <psemek/geom/simplex.hpp>
#include <psemek/geom/matrix.hpp> #include <psemek/geom/matrix.hpp>
#include <psemek/util/assert.hpp>
#include <cstddef> #include <cstddef>
#include <tuple> #include <tuple>
#include <type_traits> #include <type_traits>
@ -477,10 +479,17 @@ namespace psemek::gfx
void draw() const override void draw() const override
{ {
if (count_ == 0) return; draw(0, count_);
}
void draw(GLsizei first, GLsizei count) const
{
assert(first + count <= count_);
if (count == 0) return;
gl::BindVertexArray(array_); gl::BindVertexArray(array_);
gl::DrawArrays(primitive_type_, 0, count_); gl::DrawArrays(primitive_type_, first, count);
} }
GLsizei count() const GLsizei count() const
@ -599,10 +608,16 @@ namespace psemek::gfx
void draw() const override void draw() const override
{ {
if (count_ == 0) return; draw(0, count_);
}
void draw(GLsizei first, GLsizei count) const
{
if (count == 0) return;
assert(first + count <= count_);
gl::BindVertexArray(array_); gl::BindVertexArray(array_);
gl::DrawElements(primitive_type_, count_, index_type_, nullptr); gl::DrawElements(primitive_type_, count, index_type_, reinterpret_cast<char const *>(0) + first * index_size(index_type_));
} }
GLsizei index_count() const GLsizei index_count() const
@ -628,6 +643,18 @@ namespace psemek::gfx
GLenum primitive_type_; GLenum primitive_type_;
indexed_mesh(int); indexed_mesh(int);
static std::size_t index_size(GLenum type)
{
switch (type)
{
case gl::UNSIGNED_BYTE: return 1;
case gl::UNSIGNED_SHORT: return 2;
case gl::UNSIGNED_INT: return 4;
}
assert(false);
return 0;
}
}; };
struct instanced_mesh struct instanced_mesh
@ -737,11 +764,19 @@ namespace psemek::gfx
void draw() const override void draw() const override
{ {
if (count_ == 0) return; draw(0, count_, instance_count_);
if (instance_count_ == 0) return; }
void draw(GLsizei first, GLsizei count, GLsizei instance_count) const
{
assert(first + count <= count_);
assert(instance_count <= instance_count_);
if (count == 0) return;
if (instance_count == 0) return;
gl::BindVertexArray(array_); gl::BindVertexArray(array_);
gl::DrawArraysInstanced(primitive_type_, 0, count_, instance_count_); gl::DrawArraysInstanced(primitive_type_, first, count, instance_count);
} }
GLsizei count() const GLsizei count() const